Kenneth S. Fink, MD, MGA

The growth of managed health care organizations and their emphasis on the use of primary care providers as gatekeepers has radically changed the value of a specialty designated as a provider of primary care. Classification as a primary care physician has become important to physicians because it provides a patient base and source of revenue, and it is important to patients because it allows direct access to those physicians.¹ For the most part, general internists, family physicians, and pediatricians are designated as primary care specialists. Increasingly, however, there have been efforts at the state and federal levels to designate obstetrician-gynecologists (OBGs) as primary care providers for women. A bill was introduced in 1999 before both houses of the 106th Congress (S. 6 and H.R. 358, The Patients’ Bill of Rights Act of 1999) that would allow women to choose OBGs as their primary care physicians, and it is still awaiting action.

Traditionally, the specialty of obstetrics-gynecology has considered itself expert in the areas of reproductive health and gynecologic diseases.^2-4 Recently, changing practice philosophy has resulted in an increasing emphasis on providing general medical care.^5-7 In 1993, the American College of Obstetricians and Gynecologists (ACOG) formed a Task Force on Primary and Preventive Healthcare that identified 3 levels of care that can be provided by OBGs: traditional specialty care, primary preventive care, and extended primary care.⁸ OBGs providing primary preventive care take a broader role in health maintenance for women, including health screening and disease prevention. Those providing extended primary care offer primary preventive care and treat medical conditions beyond those pertaining to the reproductive system. Although OBGs have been divided over their role as primary care physicians, a primary care requirement in residency training was implemented in 1996.^3,5

The Committee on the Future of Primary Care of the Institute of Medicine (IOM) defined primary care as “the provision of integrated, accessible health care services by clinicians who are accountable for addressing a large majority of personal health care needs.”⁹ Included in the description of integrated is comprehensive, which means providing care for any health problem at any given stage of a patient’s life cycle. Addressing the majority of health care needs refers to the primary care physician receiving all problems that patients bring—unrestricted by organ system—and having the appropriate training to diagnose and manage the majority of them. Caring for a broad spectrum of medical problems encompassing many organ systems is a component of primary care, and this component is what is included in the ACOG definition of extended primary care. Throughout this article the term primary care will be used to represent the broad-spectrum care accepted by the IOM and ACOG as an element of primary care.

Few studies have measured the degree to which OBGs provide primary care.^10-13 Of those that have, many are based on surveys completed by patients or physicians and are focused on women in their reproductive years. Horton and colleagues¹⁰ surveyed a national random sample of 1250 ACOG members in a variety of practices and found that more than 90% of the responding OBGs performed blood pressure screening, breast examinations, mammography, and Papanicolaou tests. Hendrix and coworkers11 reviewed 739 patient encounters from 335 charts of the private practices of faculty in the Department of Obstetrics and Gynecology at Wayne State University and found that of nonobstetrical visits, 80% were for primary gynecologic care and 7% for primary nongynecologic care. Leader and Perales¹² reviewed data from a 1991 economic survey conducted by ACOG of a stratified random sample of 2000 of its members practicing in the United States. Of 1286 respondants, 48% considered themselves primary care providers. A recent study by Jacoby and colleagues¹⁴ used Medicare claims data to examine the scope of care that OBGs provided to their elderly patients. They found that OBGs provided a substantial amount of preventive care but not much nongynecologic care for elderly women.

We extend the work of these investigators by further exploring the breadth of medical conditions for which OBGs provide care to their elderly patients and by examining the degree to which OBGs in both rural and urban areas care for nongynecologic conditions. Our findings can offer some understanding of the potential impact of legislation to designate OBGs as primary care providers for elderly women.

Methods

Data Sources

We used the 1994 Washington State Medicare Part B claims file as the data source for our study. This database, part of the National Claims History File of the Health Care Financing Administration (HCFA), is an administrative data set that captures diagnostic and therapeutic information about services billed to Medicare. The Medicare Part B file contains a series of line items with each representing a discrete billable service for a Medicare beneficiary. These line items included identifiers for the patient receiving the service, the physician providing the service, the diagnosis coded, and the date of the visit. Items submitted by physicians include a unique physician identification number (UPIN) used to designate the specialty of the physician providing these services.

Physician Sample

All physicians practicing in the state of Washington and submitting Medicare claims for patient visits in 1994 were eligible for the study. We focused on the approximately 80% of OBGs who were participating in Medicare Part B. A variety of subspecialties including 5 medical (dermatology, cardiology, gastroenterology, pulmonology, and rheumatology) and 4 surgical (general surgery, orthopedic surgery, otolaryngology, and urology) were selected for comparison. Family practice and internal medicine were included in the descriptive analysis of visit frequency but not in the domain analysis, because all of primary care for elderly women was considered within the domain of these 2 specialties.

Information from the HCFA UPIN National Directory, the American Board of Medical Specialties (ABMS) database, and the American Medical Association (AMA) masterfile were used to link specialty information to the UPINs in the Part B Medicare file. Physicians were designated as a specific specialty type if both the ABMS certification and the primary self-designated specialty captured in the AMA masterfile were the same. In cases where these differed, the physicians were excluded. Including only those physicians who had the same specialty of training as their reported specialty of practice ensured accurate assignment of specialty.

Practice Location

Physicians were designated as practicing in rural or urban areas based on the ZIP codes of their practice addresses. ZIP codes were assigned as rural or urban on the basis of their proximity to a hospital classified as such by the Washington State Office of Rural Health of the Department of Health. The 5 physicians whose practice addresses were unknown or were in both rural and urban areas were excluded from the practice location analysis.

Patient Visits and Sample

We aggregated all outpatient physician services (eg, diagnostic tests and procedures) provided to an individual on a single date by the same provider into medical encounters. We used the current procedural terminology (CPT) and the HCFA common procedure coding system (HCPCS) for these services to determine whether they involved face-to-face contact with a physician. Those encounters that included such contact were considered visits. Within each visit, we chose one face-to-face line item—the index line—to identify the primary diagnosis for that visit. This index line either contained the evaluation and management code or, in cases without such a code, the face-to-face line item with the highest allowable charge. The International Classification of Diseases, Ninth Revision (ICD-9) diagnosis codes for these index lines were used to identify the primary diagnosis for each visit.¹⁵

We included women patients of the study physicians who were aged 65 years and older, enrolled in Medicare Part B, and alive throughout 1994. We excluded the 15% of patients enrolled in a managed care plan during the year to select elderly patients with unrestricted access to physicians in any specialty and because patient visit data were not available for those enrolled in those plans.

Designation of Specialty Domain

To interpret the claims-based diagnoses for each visit, we used diagnosis clusters to collapse the ICD-9 system into 120 groupings of individual diagnostic codes.^16,17 The codes in each group share similar pathophysiologic characteristics that often receive similar management. Two physicians reviewed the diagnosis clusters and nonclustered individual ICD-9 diagnoses to identify conditions traditionally cared for by physicians in each specialty. These diagnoses were designated as “in domain”; all others were designated as “out of domain.” Domain assignments were then reviewed and revised by the Medicare Carrier Advisory Committee, which was composed of specialists including all of those represented in our study.

For example, the diagnosis of peptic ulcer disease is considered out of domain for an OBG but in domain for a gastroenterologist, while cervical dysplasia is considered in domain for an OBG but out of domain for a gastroenterologist. We considered out of domain care as a measure of the breadth of care provided. The more out of domain care an OBG provided, the greater the degree of primary care that he or she was providing.

Analysis

We examined the distribution of out of domain visits for individual OBGs and the frequency of all diagnoses and out of domain diagnoses for OBGs in total. We also described visit volumes and percentage of out of domain visits in both rural and urban areas for OBGs and other physician specialists.

Results

Of the 328 Washington physicians in 1994 who submitted Medicare claims and were designated as OBGs by either the ABMS or the AMA masterfile, 285 were designated OBGs by both the ABMS and the AMA masterfile. These 285 OBGs treated 10,522 Medicare patients for 16,743 visits. These patients made a total of 108,720 visits to all physicians during the year. The patients of OBGs averaged 1.6 visits to them and 10.3 visits to any physician over the year. Patients who visited OBGs received 15.4% of their total health care from them.

The visit rate to OBGs (1.6) was the lowest for all the specialties studied; however, it closely resembled rates from other surgical specialties that ranged from 1.8 to 2.4 visits per patient. Medical specialists averaged 1.9 to 3.7 visits per patient, and traditional generalists ranged from 3.7 to 3.8 visits per patient. Of the specialties studied, the percentage of overall health care for patients of physicians of a certain specialty received by those physicians was the third lowest for OBGs (15.4%). This amount was similar to surgical specialists who ranged from 15.3% to 18.9%. Medical specialists ranged from 17.8% to 27.1%, and the patients who saw a family physician or general internist received more than 40% of their total health care from them during the year.

Of the 16,743 visits made to OBGs, 12.2% had diagnoses that were out of domain for the specialty Table 1. Among surgical specialists, general surgeons had the highest percentage of out of domain visits (21.9%), while others had a much lower proportion of out of domain visits (1.5% to 4.5%). Among medical specialists, pulmonologists had the highest percentage of out of domain visits (29.7%); others ranged from 1.2% to 15.0%.

Almost 12% of OBGs had more than 30% of their visits out of domain Figure 1. The median percentage of out of domain visits for individual OBGs was 6.7%. Table 1 shows that rural OBGs provided less out of domain care (8.2%) than their urban counterparts (12.9%). General surgeons were similar to OBGs in providing less out of domain care in the rural setting than urban setting. All the other specialties had the same or more out of domain care in the rural setting than in the urban setting.

Two of the 15 most frequent diagnosis clusters recorded by OBGs were for out of domain care Table 2. The general medical examination was the fifth most frequently reported diagnosis cluster and the most frequent out of domain diagnosis cluster Table 3. Hypertension was the other out of domain diagnosis cluster in the top 15 and comprised 9.0% of all of the out of domain diagnoses. The other out of domain problems diagnosed by OBGs include a full range of primary care conditions.

Discussion

Our study demonstrates that during 1994, the large majority of OBGs provided a limited amount of nongynecologic care to their elderly patients. This is consistent with the findings of other studies examining the scope of OBGs’ practices and suggests that in general OBGs were not serving as primary care providers to their elderly patients.^{11,13-15,17,18}

The visit rates to OBGs were more similar to surgical subspecialties than to the traditional primary care specialties. The number of visits per Medicare patient to OBGs was 1.6, the lowest of the specialties studied and very different from that of traditional primary care specialists (3.7 to 3.8 per patient). Patients of OBGs received 15.4% of their total health care from OBGs, which was much lower than the amount of overall health care that traditional generalists provided to their patients (42.0%-42.9%). This suggests that OBGs were primarily seeing elderly patients in consultation for gynecologic problems. This is consistent with a number of studies that have demonstrated that elderly women are less likely to receive care from OBGs.^10,12,19-22

Our finding that few OBGs provided broad-spectrum care in 1994 suggests that legislation to increase the use of OBGs as primary care providers could affect the way general medical services are delivered to elderly women. Many of these women may have nongynecologic medical conditions requiring treatment and monitoring. If most OBGs do not routinely provide these services, these women will require referral to medical specialists, which could lead to increasing costs, inconvenience, and fragmentation of care.

We did not expect the findings that rural OBGs provided less nongynecologic care than urban OBGs. Because rural areas are often underserved, we hypothesized that rural OBGs would practice as generalists more often and provide more general medical care. We concluded, therefore, that rural OBGs may be in shorter supply than generalists and that they are filling their practices with visits specific to their specialty. In addition, there may be increased competition among urban OBGs for gynecologic visits, so a larger number of patients are seen for nongynecologic problems.

Limitations

Our study has several limitations. We included only the primary diagnosis for each visit. A patient may have presented with both a gynecologic and non-gynecologic problem, but the OBG may have coded the gynecologic diagnosis as the primary one. In addition, patients presenting for a gynecologic complaint may inquire as an aside about a nongynecologic concern that may have been addressed but not coded. This would underestimate the amount of nongynecologic care provided by OBGs as well as the other studied specialists. However, it is unlikely that every time a woman visits an OBG for an upper respiratory infection, joint pain, or glycohemoglobin monitoring she also has an active gynecologic problem. The methodology we used should identify the portion of OBGs who provided a substantial amount of nongynecologic care.

The scope of OBGs’ practices may have changed since the data were collected. The primary reason for such a change would be the implementation of the primary care requirement during residency. Since that change in training occurred in 1996, however, those residents affected are just now entering the work force. Thus, our study’s data are likely to represent current practice patterns. A follow-up study of the scope of OBGs’ practices in 5 to 10 years will help elucidate the effect of the residency primary care requirement on OBGs’ practices.

The assignment of a diagnosis as in or out of domain is subject to interpretation. ICD-9 codes and diagnosis clusters were reviewed separately by 2 physicians to classify the diagnoses. When there was disagreement, the individuals discussed the diagnosis to reach consensus. If they could not agree, the diagnosis was considered out of domain. For example, the general medical examination was considered out of domain because the exact nature of the visit is unclear; however, the diagnosis may have been used for general gynecologic services provided to women without specific diagnoses, such as annual Papanicolaou tests that would be considered in domain. Since this was a conservative approach, it could overestimate the amount of out of domain care provided.

Only one feature of primary care—the breadth of practice—was addressed in this study. We did not examine a number of other features that also characterize primary care—continuity, coordination, and accessibility—as also described by the Committee on the Future of Primary Care of the IOM.⁹ In addition, we did not address quality of care.

Since we limited our study to Washington Medicare beneficiaries aged 65 years and older, we cannot comment on the degree to which OBGs may be providing general medical care to patients younger than 65 years. Younger patients may have different relationships with their physicians and present with different medical issues of varying complexity. We also excluded the 15% of Medicare elderly in Washington who in 1994 were enrolled in a managed care health plan. These results cannot be extrapolated to this population, because nearly all health maintenance organizations restrict access to specialists.

The Effect of Legislation

Our findings raise the question of whether legislation that designates OBGs as primary care providers for elderly women would result in an increase in the use of OBGs as providers of care for problems outside the reproductive system or primarily increase access to OBGs’ specialty services. Passage of legislation such as the Patients’ Bill of Rights Act of 1999 may facilitate elderly women’s obtaining primary gynecologic care, yet it may not have the same effect on their receipt of general medical care. A bill like this would allow women of all ages to designate OBGs as their primary care providers, thus allowing unrestricted and direct access to their services. Studies investigating the care received by elderly women enrolled in private health care plans in which they are able to select OBGs as primary care physicians could provide additional useful information. If the Patients’ Bill of Rights Act of 1999 or similar legislation is passed, studies will be needed to assess its effect on the overall medical care received by elderly women.

Conclusions

In 1994, few OBGs were providing the level of care that ACOG designates as extended primary care and that the IOM considers primary care. Our study does not reflect the degree to which they might have been providing primary preventive care and does not examine OBGs’ abilities to provide care for nongynecologic problems. The extent to which these findings represent current practice is also unknown. Nonetheless, our findings provide a baseline for the type of care provided by OBGs and suggest that without changes in the scope of OBGs’ practice, legislation resulting in more elderly women using OBGs as their primary providers could result in greater fragmentation and costs for their overall medical care.

Alternatively, some OBGs could embrace the movement within their specialty to emphasize treating patients’ general medical problems. OBGs develop close relationships with patients during their reproductive years, and these patients may benefit from a continuing relationship with these physicians as they age. There have been recent changes in obstetrics-gynecology residency requirements, increasing the time spent training in general medicine to better prepare residents to provide nongynecologic care. Other specialties have developed training tracks to specifically prepare physicians to practice primary care. Perhaps this is the time for residency programs in obstetrics-gynecology to do the same for a subset of their residents specifically interested in providing primary care.

Acknowledgments

Our research was supported by grants from the Robert Wood Johnson Foundation, Princeton, NJ, and the Office of Rural Health Policy and the Agency for Health Care Policy and Research of the US Public Health Service, Washington, DC. The views expressed in this article are those of the authors and do not necessarily represent those of the University of Washington, the Health Care Financing Administration, or the Robert Wood Johnson Foundation. The authors would like to acknowledge Peter Houck, MD, for his contributions to the manuscript and Durlin Hickok, MD, MPH, for reviewing the manuscript.

The growth of managed health care organizations and their emphasis on the use of primary care providers as gatekeepers has radically changed the value of a specialty designated as a provider of primary care. Classification as a primary care physician has become important to physicians because it provides a patient base and source of revenue, and it is important to patients because it allows direct access to those physicians.¹ For the most part, general internists, family physicians, and pediatricians are designated as primary care specialists. Increasingly, however, there have been efforts at the state and federal levels to designate obstetrician-gynecologists (OBGs) as primary care providers for women. A bill was introduced in 1999 before both houses of the 106th Congress (S. 6 and H.R. 358, The Patients’ Bill of Rights Act of 1999) that would allow women to choose OBGs as their primary care physicians, and it is still awaiting action.

Traditionally, the specialty of obstetrics-gynecology has considered itself expert in the areas of reproductive health and gynecologic diseases.^2-4 Recently, changing practice philosophy has resulted in an increasing emphasis on providing general medical care.^5-7 In 1993, the American College of Obstetricians and Gynecologists (ACOG) formed a Task Force on Primary and Preventive Healthcare that identified 3 levels of care that can be provided by OBGs: traditional specialty care, primary preventive care, and extended primary care.⁸ OBGs providing primary preventive care take a broader role in health maintenance for women, including health screening and disease prevention. Those providing extended primary care offer primary preventive care and treat medical conditions beyond those pertaining to the reproductive system. Although OBGs have been divided over their role as primary care physicians, a primary care requirement in residency training was implemented in 1996.^3,5

The Committee on the Future of Primary Care of the Institute of Medicine (IOM) defined primary care as “the provision of integrated, accessible health care services by clinicians who are accountable for addressing a large majority of personal health care needs.”⁹ Included in the description of integrated is comprehensive, which means providing care for any health problem at any given stage of a patient’s life cycle. Addressing the majority of health care needs refers to the primary care physician receiving all problems that patients bring—unrestricted by organ system—and having the appropriate training to diagnose and manage the majority of them. Caring for a broad spectrum of medical problems encompassing many organ systems is a component of primary care, and this component is what is included in the ACOG definition of extended primary care. Throughout this article the term primary care will be used to represent the broad-spectrum care accepted by the IOM and ACOG as an element of primary care.

Few studies have measured the degree to which OBGs provide primary care.^10-13 Of those that have, many are based on surveys completed by patients or physicians and are focused on women in their reproductive years. Horton and colleagues¹⁰ surveyed a national random sample of 1250 ACOG members in a variety of practices and found that more than 90% of the responding OBGs performed blood pressure screening, breast examinations, mammography, and Papanicolaou tests. Hendrix and coworkers11 reviewed 739 patient encounters from 335 charts of the private practices of faculty in the Department of Obstetrics and Gynecology at Wayne State University and found that of nonobstetrical visits, 80% were for primary gynecologic care and 7% for primary nongynecologic care. Leader and Perales¹² reviewed data from a 1991 economic survey conducted by ACOG of a stratified random sample of 2000 of its members practicing in the United States. Of 1286 respondants, 48% considered themselves primary care providers. A recent study by Jacoby and colleagues¹⁴ used Medicare claims data to examine the scope of care that OBGs provided to their elderly patients. They found that OBGs provided a substantial amount of preventive care but not much nongynecologic care for elderly women.

We extend the work of these investigators by further exploring the breadth of medical conditions for which OBGs provide care to their elderly patients and by examining the degree to which OBGs in both rural and urban areas care for nongynecologic conditions. Our findings can offer some understanding of the potential impact of legislation to designate OBGs as primary care providers for elderly women.

Methods

Data Sources

We used the 1994 Washington State Medicare Part B claims file as the data source for our study. This database, part of the National Claims History File of the Health Care Financing Administration (HCFA), is an administrative data set that captures diagnostic and therapeutic information about services billed to Medicare. The Medicare Part B file contains a series of line items with each representing a discrete billable service for a Medicare beneficiary. These line items included identifiers for the patient receiving the service, the physician providing the service, the diagnosis coded, and the date of the visit. Items submitted by physicians include a unique physician identification number (UPIN) used to designate the specialty of the physician providing these services.

Physician Sample

All physicians practicing in the state of Washington and submitting Medicare claims for patient visits in 1994 were eligible for the study. We focused on the approximately 80% of OBGs who were participating in Medicare Part B. A variety of subspecialties including 5 medical (dermatology, cardiology, gastroenterology, pulmonology, and rheumatology) and 4 surgical (general surgery, orthopedic surgery, otolaryngology, and urology) were selected for comparison. Family practice and internal medicine were included in the descriptive analysis of visit frequency but not in the domain analysis, because all of primary care for elderly women was considered within the domain of these 2 specialties.

Information from the HCFA UPIN National Directory, the American Board of Medical Specialties (ABMS) database, and the American Medical Association (AMA) masterfile were used to link specialty information to the UPINs in the Part B Medicare file. Physicians were designated as a specific specialty type if both the ABMS certification and the primary self-designated specialty captured in the AMA masterfile were the same. In cases where these differed, the physicians were excluded. Including only those physicians who had the same specialty of training as their reported specialty of practice ensured accurate assignment of specialty.

Practice Location

Physicians were designated as practicing in rural or urban areas based on the ZIP codes of their practice addresses. ZIP codes were assigned as rural or urban on the basis of their proximity to a hospital classified as such by the Washington State Office of Rural Health of the Department of Health. The 5 physicians whose practice addresses were unknown or were in both rural and urban areas were excluded from the practice location analysis.

Patient Visits and Sample

We aggregated all outpatient physician services (eg, diagnostic tests and procedures) provided to an individual on a single date by the same provider into medical encounters. We used the current procedural terminology (CPT) and the HCFA common procedure coding system (HCPCS) for these services to determine whether they involved face-to-face contact with a physician. Those encounters that included such contact were considered visits. Within each visit, we chose one face-to-face line item—the index line—to identify the primary diagnosis for that visit. This index line either contained the evaluation and management code or, in cases without such a code, the face-to-face line item with the highest allowable charge. The International Classification of Diseases, Ninth Revision (ICD-9) diagnosis codes for these index lines were used to identify the primary diagnosis for each visit.¹⁵

We included women patients of the study physicians who were aged 65 years and older, enrolled in Medicare Part B, and alive throughout 1994. We excluded the 15% of patients enrolled in a managed care plan during the year to select elderly patients with unrestricted access to physicians in any specialty and because patient visit data were not available for those enrolled in those plans.

Designation of Specialty Domain

To interpret the claims-based diagnoses for each visit, we used diagnosis clusters to collapse the ICD-9 system into 120 groupings of individual diagnostic codes.^16,17 The codes in each group share similar pathophysiologic characteristics that often receive similar management. Two physicians reviewed the diagnosis clusters and nonclustered individual ICD-9 diagnoses to identify conditions traditionally cared for by physicians in each specialty. These diagnoses were designated as “in domain”; all others were designated as “out of domain.” Domain assignments were then reviewed and revised by the Medicare Carrier Advisory Committee, which was composed of specialists including all of those represented in our study.

For example, the diagnosis of peptic ulcer disease is considered out of domain for an OBG but in domain for a gastroenterologist, while cervical dysplasia is considered in domain for an OBG but out of domain for a gastroenterologist. We considered out of domain care as a measure of the breadth of care provided. The more out of domain care an OBG provided, the greater the degree of primary care that he or she was providing.

Analysis

We examined the distribution of out of domain visits for individual OBGs and the frequency of all diagnoses and out of domain diagnoses for OBGs in total. We also described visit volumes and percentage of out of domain visits in both rural and urban areas for OBGs and other physician specialists.

Results

Of the 328 Washington physicians in 1994 who submitted Medicare claims and were designated as OBGs by either the ABMS or the AMA masterfile, 285 were designated OBGs by both the ABMS and the AMA masterfile. These 285 OBGs treated 10,522 Medicare patients for 16,743 visits. These patients made a total of 108,720 visits to all physicians during the year. The patients of OBGs averaged 1.6 visits to them and 10.3 visits to any physician over the year. Patients who visited OBGs received 15.4% of their total health care from them.

The visit rate to OBGs (1.6) was the lowest for all the specialties studied; however, it closely resembled rates from other surgical specialties that ranged from 1.8 to 2.4 visits per patient. Medical specialists averaged 1.9 to 3.7 visits per patient, and traditional generalists ranged from 3.7 to 3.8 visits per patient. Of the specialties studied, the percentage of overall health care for patients of physicians of a certain specialty received by those physicians was the third lowest for OBGs (15.4%). This amount was similar to surgical specialists who ranged from 15.3% to 18.9%. Medical specialists ranged from 17.8% to 27.1%, and the patients who saw a family physician or general internist received more than 40% of their total health care from them during the year.

Of the 16,743 visits made to OBGs, 12.2% had diagnoses that were out of domain for the specialty Table 1. Among surgical specialists, general surgeons had the highest percentage of out of domain visits (21.9%), while others had a much lower proportion of out of domain visits (1.5% to 4.5%). Among medical specialists, pulmonologists had the highest percentage of out of domain visits (29.7%); others ranged from 1.2% to 15.0%.

Almost 12% of OBGs had more than 30% of their visits out of domain Figure 1. The median percentage of out of domain visits for individual OBGs was 6.7%. Table 1 shows that rural OBGs provided less out of domain care (8.2%) than their urban counterparts (12.9%). General surgeons were similar to OBGs in providing less out of domain care in the rural setting than urban setting. All the other specialties had the same or more out of domain care in the rural setting than in the urban setting.

Two of the 15 most frequent diagnosis clusters recorded by OBGs were for out of domain care Table 2. The general medical examination was the fifth most frequently reported diagnosis cluster and the most frequent out of domain diagnosis cluster Table 3. Hypertension was the other out of domain diagnosis cluster in the top 15 and comprised 9.0% of all of the out of domain diagnoses. The other out of domain problems diagnosed by OBGs include a full range of primary care conditions.

Discussion

Our study demonstrates that during 1994, the large majority of OBGs provided a limited amount of nongynecologic care to their elderly patients. This is consistent with the findings of other studies examining the scope of OBGs’ practices and suggests that in general OBGs were not serving as primary care providers to their elderly patients.^{11,13-15,17,18}

The visit rates to OBGs were more similar to surgical subspecialties than to the traditional primary care specialties. The number of visits per Medicare patient to OBGs was 1.6, the lowest of the specialties studied and very different from that of traditional primary care specialists (3.7 to 3.8 per patient). Patients of OBGs received 15.4% of their total health care from OBGs, which was much lower than the amount of overall health care that traditional generalists provided to their patients (42.0%-42.9%). This suggests that OBGs were primarily seeing elderly patients in consultation for gynecologic problems. This is consistent with a number of studies that have demonstrated that elderly women are less likely to receive care from OBGs.^10,12,19-22

Our finding that few OBGs provided broad-spectrum care in 1994 suggests that legislation to increase the use of OBGs as primary care providers could affect the way general medical services are delivered to elderly women. Many of these women may have nongynecologic medical conditions requiring treatment and monitoring. If most OBGs do not routinely provide these services, these women will require referral to medical specialists, which could lead to increasing costs, inconvenience, and fragmentation of care.

We did not expect the findings that rural OBGs provided less nongynecologic care than urban OBGs. Because rural areas are often underserved, we hypothesized that rural OBGs would practice as generalists more often and provide more general medical care. We concluded, therefore, that rural OBGs may be in shorter supply than generalists and that they are filling their practices with visits specific to their specialty. In addition, there may be increased competition among urban OBGs for gynecologic visits, so a larger number of patients are seen for nongynecologic problems.

Limitations

Our study has several limitations. We included only the primary diagnosis for each visit. A patient may have presented with both a gynecologic and non-gynecologic problem, but the OBG may have coded the gynecologic diagnosis as the primary one. In addition, patients presenting for a gynecologic complaint may inquire as an aside about a nongynecologic concern that may have been addressed but not coded. This would underestimate the amount of nongynecologic care provided by OBGs as well as the other studied specialists. However, it is unlikely that every time a woman visits an OBG for an upper respiratory infection, joint pain, or glycohemoglobin monitoring she also has an active gynecologic problem. The methodology we used should identify the portion of OBGs who provided a substantial amount of nongynecologic care.

The scope of OBGs’ practices may have changed since the data were collected. The primary reason for such a change would be the implementation of the primary care requirement during residency. Since that change in training occurred in 1996, however, those residents affected are just now entering the work force. Thus, our study’s data are likely to represent current practice patterns. A follow-up study of the scope of OBGs’ practices in 5 to 10 years will help elucidate the effect of the residency primary care requirement on OBGs’ practices.

The assignment of a diagnosis as in or out of domain is subject to interpretation. ICD-9 codes and diagnosis clusters were reviewed separately by 2 physicians to classify the diagnoses. When there was disagreement, the individuals discussed the diagnosis to reach consensus. If they could not agree, the diagnosis was considered out of domain. For example, the general medical examination was considered out of domain because the exact nature of the visit is unclear; however, the diagnosis may have been used for general gynecologic services provided to women without specific diagnoses, such as annual Papanicolaou tests that would be considered in domain. Since this was a conservative approach, it could overestimate the amount of out of domain care provided.

Only one feature of primary care—the breadth of practice—was addressed in this study. We did not examine a number of other features that also characterize primary care—continuity, coordination, and accessibility—as also described by the Committee on the Future of Primary Care of the IOM.⁹ In addition, we did not address quality of care.

Since we limited our study to Washington Medicare beneficiaries aged 65 years and older, we cannot comment on the degree to which OBGs may be providing general medical care to patients younger than 65 years. Younger patients may have different relationships with their physicians and present with different medical issues of varying complexity. We also excluded the 15% of Medicare elderly in Washington who in 1994 were enrolled in a managed care health plan. These results cannot be extrapolated to this population, because nearly all health maintenance organizations restrict access to specialists.

The Effect of Legislation

Our findings raise the question of whether legislation that designates OBGs as primary care providers for elderly women would result in an increase in the use of OBGs as providers of care for problems outside the reproductive system or primarily increase access to OBGs’ specialty services. Passage of legislation such as the Patients’ Bill of Rights Act of 1999 may facilitate elderly women’s obtaining primary gynecologic care, yet it may not have the same effect on their receipt of general medical care. A bill like this would allow women of all ages to designate OBGs as their primary care providers, thus allowing unrestricted and direct access to their services. Studies investigating the care received by elderly women enrolled in private health care plans in which they are able to select OBGs as primary care physicians could provide additional useful information. If the Patients’ Bill of Rights Act of 1999 or similar legislation is passed, studies will be needed to assess its effect on the overall medical care received by elderly women.

Conclusions

In 1994, few OBGs were providing the level of care that ACOG designates as extended primary care and that the IOM considers primary care. Our study does not reflect the degree to which they might have been providing primary preventive care and does not examine OBGs’ abilities to provide care for nongynecologic problems. The extent to which these findings represent current practice is also unknown. Nonetheless, our findings provide a baseline for the type of care provided by OBGs and suggest that without changes in the scope of OBGs’ practice, legislation resulting in more elderly women using OBGs as their primary providers could result in greater fragmentation and costs for their overall medical care.

Alternatively, some OBGs could embrace the movement within their specialty to emphasize treating patients’ general medical problems. OBGs develop close relationships with patients during their reproductive years, and these patients may benefit from a continuing relationship with these physicians as they age. There have been recent changes in obstetrics-gynecology residency requirements, increasing the time spent training in general medicine to better prepare residents to provide nongynecologic care. Other specialties have developed training tracks to specifically prepare physicians to practice primary care. Perhaps this is the time for residency programs in obstetrics-gynecology to do the same for a subset of their residents specifically interested in providing primary care.

Acknowledgments

Our research was supported by grants from the Robert Wood Johnson Foundation, Princeton, NJ, and the Office of Rural Health Policy and the Agency for Health Care Policy and Research of the US Public Health Service, Washington, DC. The views expressed in this article are those of the authors and do not necessarily represent those of the University of Washington, the Health Care Financing Administration, or the Robert Wood Johnson Foundation. The authors would like to acknowledge Peter Houck, MD, for his contributions to the manuscript and Durlin Hickok, MD, MPH, for reviewing the manuscript.

The growth of managed health care organizations and their emphasis on the use of primary care providers as gatekeepers has radically changed the value of a specialty designated as a provider of primary care. Classification as a primary care physician has become important to physicians because it provides a patient base and source of revenue, and it is important to patients because it allows direct access to those physicians.¹ For the most part, general internists, family physicians, and pediatricians are designated as primary care specialists. Increasingly, however, there have been efforts at the state and federal levels to designate obstetrician-gynecologists (OBGs) as primary care providers for women. A bill was introduced in 1999 before both houses of the 106th Congress (S. 6 and H.R. 358, The Patients’ Bill of Rights Act of 1999) that would allow women to choose OBGs as their primary care physicians, and it is still awaiting action.

Traditionally, the specialty of obstetrics-gynecology has considered itself expert in the areas of reproductive health and gynecologic diseases.^2-4 Recently, changing practice philosophy has resulted in an increasing emphasis on providing general medical care.^5-7 In 1993, the American College of Obstetricians and Gynecologists (ACOG) formed a Task Force on Primary and Preventive Healthcare that identified 3 levels of care that can be provided by OBGs: traditional specialty care, primary preventive care, and extended primary care.⁸ OBGs providing primary preventive care take a broader role in health maintenance for women, including health screening and disease prevention. Those providing extended primary care offer primary preventive care and treat medical conditions beyond those pertaining to the reproductive system. Although OBGs have been divided over their role as primary care physicians, a primary care requirement in residency training was implemented in 1996.^3,5

The Committee on the Future of Primary Care of the Institute of Medicine (IOM) defined primary care as “the provision of integrated, accessible health care services by clinicians who are accountable for addressing a large majority of personal health care needs.”⁹ Included in the description of integrated is comprehensive, which means providing care for any health problem at any given stage of a patient’s life cycle. Addressing the majority of health care needs refers to the primary care physician receiving all problems that patients bring—unrestricted by organ system—and having the appropriate training to diagnose and manage the majority of them. Caring for a broad spectrum of medical problems encompassing many organ systems is a component of primary care, and this component is what is included in the ACOG definition of extended primary care. Throughout this article the term primary care will be used to represent the broad-spectrum care accepted by the IOM and ACOG as an element of primary care.

Few studies have measured the degree to which OBGs provide primary care.^10-13 Of those that have, many are based on surveys completed by patients or physicians and are focused on women in their reproductive years. Horton and colleagues¹⁰ surveyed a national random sample of 1250 ACOG members in a variety of practices and found that more than 90% of the responding OBGs performed blood pressure screening, breast examinations, mammography, and Papanicolaou tests. Hendrix and coworkers11 reviewed 739 patient encounters from 335 charts of the private practices of faculty in the Department of Obstetrics and Gynecology at Wayne State University and found that of nonobstetrical visits, 80% were for primary gynecologic care and 7% for primary nongynecologic care. Leader and Perales¹² reviewed data from a 1991 economic survey conducted by ACOG of a stratified random sample of 2000 of its members practicing in the United States. Of 1286 respondants, 48% considered themselves primary care providers. A recent study by Jacoby and colleagues¹⁴ used Medicare claims data to examine the scope of care that OBGs provided to their elderly patients. They found that OBGs provided a substantial amount of preventive care but not much nongynecologic care for elderly women.

We extend the work of these investigators by further exploring the breadth of medical conditions for which OBGs provide care to their elderly patients and by examining the degree to which OBGs in both rural and urban areas care for nongynecologic conditions. Our findings can offer some understanding of the potential impact of legislation to designate OBGs as primary care providers for elderly women.

Methods

Data Sources

We used the 1994 Washington State Medicare Part B claims file as the data source for our study. This database, part of the National Claims History File of the Health Care Financing Administration (HCFA), is an administrative data set that captures diagnostic and therapeutic information about services billed to Medicare. The Medicare Part B file contains a series of line items with each representing a discrete billable service for a Medicare beneficiary. These line items included identifiers for the patient receiving the service, the physician providing the service, the diagnosis coded, and the date of the visit. Items submitted by physicians include a unique physician identification number (UPIN) used to designate the specialty of the physician providing these services.

Physician Sample

All physicians practicing in the state of Washington and submitting Medicare claims for patient visits in 1994 were eligible for the study. We focused on the approximately 80% of OBGs who were participating in Medicare Part B. A variety of subspecialties including 5 medical (dermatology, cardiology, gastroenterology, pulmonology, and rheumatology) and 4 surgical (general surgery, orthopedic surgery, otolaryngology, and urology) were selected for comparison. Family practice and internal medicine were included in the descriptive analysis of visit frequency but not in the domain analysis, because all of primary care for elderly women was considered within the domain of these 2 specialties.

Information from the HCFA UPIN National Directory, the American Board of Medical Specialties (ABMS) database, and the American Medical Association (AMA) masterfile were used to link specialty information to the UPINs in the Part B Medicare file. Physicians were designated as a specific specialty type if both the ABMS certification and the primary self-designated specialty captured in the AMA masterfile were the same. In cases where these differed, the physicians were excluded. Including only those physicians who had the same specialty of training as their reported specialty of practice ensured accurate assignment of specialty.

Practice Location

Physicians were designated as practicing in rural or urban areas based on the ZIP codes of their practice addresses. ZIP codes were assigned as rural or urban on the basis of their proximity to a hospital classified as such by the Washington State Office of Rural Health of the Department of Health. The 5 physicians whose practice addresses were unknown or were in both rural and urban areas were excluded from the practice location analysis.

Patient Visits and Sample

We aggregated all outpatient physician services (eg, diagnostic tests and procedures) provided to an individual on a single date by the same provider into medical encounters. We used the current procedural terminology (CPT) and the HCFA common procedure coding system (HCPCS) for these services to determine whether they involved face-to-face contact with a physician. Those encounters that included such contact were considered visits. Within each visit, we chose one face-to-face line item—the index line—to identify the primary diagnosis for that visit. This index line either contained the evaluation and management code or, in cases without such a code, the face-to-face line item with the highest allowable charge. The International Classification of Diseases, Ninth Revision (ICD-9) diagnosis codes for these index lines were used to identify the primary diagnosis for each visit.¹⁵

We included women patients of the study physicians who were aged 65 years and older, enrolled in Medicare Part B, and alive throughout 1994. We excluded the 15% of patients enrolled in a managed care plan during the year to select elderly patients with unrestricted access to physicians in any specialty and because patient visit data were not available for those enrolled in those plans.

Designation of Specialty Domain

To interpret the claims-based diagnoses for each visit, we used diagnosis clusters to collapse the ICD-9 system into 120 groupings of individual diagnostic codes.^16,17 The codes in each group share similar pathophysiologic characteristics that often receive similar management. Two physicians reviewed the diagnosis clusters and nonclustered individual ICD-9 diagnoses to identify conditions traditionally cared for by physicians in each specialty. These diagnoses were designated as “in domain”; all others were designated as “out of domain.” Domain assignments were then reviewed and revised by the Medicare Carrier Advisory Committee, which was composed of specialists including all of those represented in our study.

For example, the diagnosis of peptic ulcer disease is considered out of domain for an OBG but in domain for a gastroenterologist, while cervical dysplasia is considered in domain for an OBG but out of domain for a gastroenterologist. We considered out of domain care as a measure of the breadth of care provided. The more out of domain care an OBG provided, the greater the degree of primary care that he or she was providing.

Analysis

We examined the distribution of out of domain visits for individual OBGs and the frequency of all diagnoses and out of domain diagnoses for OBGs in total. We also described visit volumes and percentage of out of domain visits in both rural and urban areas for OBGs and other physician specialists.

Results

Of the 328 Washington physicians in 1994 who submitted Medicare claims and were designated as OBGs by either the ABMS or the AMA masterfile, 285 were designated OBGs by both the ABMS and the AMA masterfile. These 285 OBGs treated 10,522 Medicare patients for 16,743 visits. These patients made a total of 108,720 visits to all physicians during the year. The patients of OBGs averaged 1.6 visits to them and 10.3 visits to any physician over the year. Patients who visited OBGs received 15.4% of their total health care from them.

The visit rate to OBGs (1.6) was the lowest for all the specialties studied; however, it closely resembled rates from other surgical specialties that ranged from 1.8 to 2.4 visits per patient. Medical specialists averaged 1.9 to 3.7 visits per patient, and traditional generalists ranged from 3.7 to 3.8 visits per patient. Of the specialties studied, the percentage of overall health care for patients of physicians of a certain specialty received by those physicians was the third lowest for OBGs (15.4%). This amount was similar to surgical specialists who ranged from 15.3% to 18.9%. Medical specialists ranged from 17.8% to 27.1%, and the patients who saw a family physician or general internist received more than 40% of their total health care from them during the year.

Of the 16,743 visits made to OBGs, 12.2% had diagnoses that were out of domain for the specialty Table 1. Among surgical specialists, general surgeons had the highest percentage of out of domain visits (21.9%), while others had a much lower proportion of out of domain visits (1.5% to 4.5%). Among medical specialists, pulmonologists had the highest percentage of out of domain visits (29.7%); others ranged from 1.2% to 15.0%.

Almost 12% of OBGs had more than 30% of their visits out of domain Figure 1. The median percentage of out of domain visits for individual OBGs was 6.7%. Table 1 shows that rural OBGs provided less out of domain care (8.2%) than their urban counterparts (12.9%). General surgeons were similar to OBGs in providing less out of domain care in the rural setting than urban setting. All the other specialties had the same or more out of domain care in the rural setting than in the urban setting.

Two of the 15 most frequent diagnosis clusters recorded by OBGs were for out of domain care Table 2. The general medical examination was the fifth most frequently reported diagnosis cluster and the most frequent out of domain diagnosis cluster Table 3. Hypertension was the other out of domain diagnosis cluster in the top 15 and comprised 9.0% of all of the out of domain diagnoses. The other out of domain problems diagnosed by OBGs include a full range of primary care conditions.

Discussion

Our study demonstrates that during 1994, the large majority of OBGs provided a limited amount of nongynecologic care to their elderly patients. This is consistent with the findings of other studies examining the scope of OBGs’ practices and suggests that in general OBGs were not serving as primary care providers to their elderly patients.^{11,13-15,17,18}

The visit rates to OBGs were more similar to surgical subspecialties than to the traditional primary care specialties. The number of visits per Medicare patient to OBGs was 1.6, the lowest of the specialties studied and very different from that of traditional primary care specialists (3.7 to 3.8 per patient). Patients of OBGs received 15.4% of their total health care from OBGs, which was much lower than the amount of overall health care that traditional generalists provided to their patients (42.0%-42.9%). This suggests that OBGs were primarily seeing elderly patients in consultation for gynecologic problems. This is consistent with a number of studies that have demonstrated that elderly women are less likely to receive care from OBGs.^10,12,19-22

Our finding that few OBGs provided broad-spectrum care in 1994 suggests that legislation to increase the use of OBGs as primary care providers could affect the way general medical services are delivered to elderly women. Many of these women may have nongynecologic medical conditions requiring treatment and monitoring. If most OBGs do not routinely provide these services, these women will require referral to medical specialists, which could lead to increasing costs, inconvenience, and fragmentation of care.

We did not expect the findings that rural OBGs provided less nongynecologic care than urban OBGs. Because rural areas are often underserved, we hypothesized that rural OBGs would practice as generalists more often and provide more general medical care. We concluded, therefore, that rural OBGs may be in shorter supply than generalists and that they are filling their practices with visits specific to their specialty. In addition, there may be increased competition among urban OBGs for gynecologic visits, so a larger number of patients are seen for nongynecologic problems.

Limitations

Our study has several limitations. We included only the primary diagnosis for each visit. A patient may have presented with both a gynecologic and non-gynecologic problem, but the OBG may have coded the gynecologic diagnosis as the primary one. In addition, patients presenting for a gynecologic complaint may inquire as an aside about a nongynecologic concern that may have been addressed but not coded. This would underestimate the amount of nongynecologic care provided by OBGs as well as the other studied specialists. However, it is unlikely that every time a woman visits an OBG for an upper respiratory infection, joint pain, or glycohemoglobin monitoring she also has an active gynecologic problem. The methodology we used should identify the portion of OBGs who provided a substantial amount of nongynecologic care.

The scope of OBGs’ practices may have changed since the data were collected. The primary reason for such a change would be the implementation of the primary care requirement during residency. Since that change in training occurred in 1996, however, those residents affected are just now entering the work force. Thus, our study’s data are likely to represent current practice patterns. A follow-up study of the scope of OBGs’ practices in 5 to 10 years will help elucidate the effect of the residency primary care requirement on OBGs’ practices.

The assignment of a diagnosis as in or out of domain is subject to interpretation. ICD-9 codes and diagnosis clusters were reviewed separately by 2 physicians to classify the diagnoses. When there was disagreement, the individuals discussed the diagnosis to reach consensus. If they could not agree, the diagnosis was considered out of domain. For example, the general medical examination was considered out of domain because the exact nature of the visit is unclear; however, the diagnosis may have been used for general gynecologic services provided to women without specific diagnoses, such as annual Papanicolaou tests that would be considered in domain. Since this was a conservative approach, it could overestimate the amount of out of domain care provided.

Only one feature of primary care—the breadth of practice—was addressed in this study. We did not examine a number of other features that also characterize primary care—continuity, coordination, and accessibility—as also described by the Committee on the Future of Primary Care of the IOM.⁹ In addition, we did not address quality of care.

Since we limited our study to Washington Medicare beneficiaries aged 65 years and older, we cannot comment on the degree to which OBGs may be providing general medical care to patients younger than 65 years. Younger patients may have different relationships with their physicians and present with different medical issues of varying complexity. We also excluded the 15% of Medicare elderly in Washington who in 1994 were enrolled in a managed care health plan. These results cannot be extrapolated to this population, because nearly all health maintenance organizations restrict access to specialists.

The Effect of Legislation

Our findings raise the question of whether legislation that designates OBGs as primary care providers for elderly women would result in an increase in the use of OBGs as providers of care for problems outside the reproductive system or primarily increase access to OBGs’ specialty services. Passage of legislation such as the Patients’ Bill of Rights Act of 1999 may facilitate elderly women’s obtaining primary gynecologic care, yet it may not have the same effect on their receipt of general medical care. A bill like this would allow women of all ages to designate OBGs as their primary care providers, thus allowing unrestricted and direct access to their services. Studies investigating the care received by elderly women enrolled in private health care plans in which they are able to select OBGs as primary care physicians could provide additional useful information. If the Patients’ Bill of Rights Act of 1999 or similar legislation is passed, studies will be needed to assess its effect on the overall medical care received by elderly women.

Conclusions

In 1994, few OBGs were providing the level of care that ACOG designates as extended primary care and that the IOM considers primary care. Our study does not reflect the degree to which they might have been providing primary preventive care and does not examine OBGs’ abilities to provide care for nongynecologic problems. The extent to which these findings represent current practice is also unknown. Nonetheless, our findings provide a baseline for the type of care provided by OBGs and suggest that without changes in the scope of OBGs’ practice, legislation resulting in more elderly women using OBGs as their primary providers could result in greater fragmentation and costs for their overall medical care.

Alternatively, some OBGs could embrace the movement within their specialty to emphasize treating patients’ general medical problems. OBGs develop close relationships with patients during their reproductive years, and these patients may benefit from a continuing relationship with these physicians as they age. There have been recent changes in obstetrics-gynecology residency requirements, increasing the time spent training in general medicine to better prepare residents to provide nongynecologic care. Other specialties have developed training tracks to specifically prepare physicians to practice primary care. Perhaps this is the time for residency programs in obstetrics-gynecology to do the same for a subset of their residents specifically interested in providing primary care.

Acknowledgments

Our research was supported by grants from the Robert Wood Johnson Foundation, Princeton, NJ, and the Office of Rural Health Policy and the Agency for Health Care Policy and Research of the US Public Health Service, Washington, DC. The views expressed in this article are those of the authors and do not necessarily represent those of the University of Washington, the Health Care Financing Administration, or the Robert Wood Johnson Foundation. The authors would like to acknowledge Peter Houck, MD, for his contributions to the manuscript and Durlin Hickok, MD, MPH, for reviewing the manuscript.