Group Office Visits Change Dietary Habits of Patients with Coronary Artery Disease: The Dietary Intervention and Evaluation Trial (D.I.E.T.)

It is well established that nearly half of all Americans will die of cardiovascular disease. Lipid-lowering trials^1,2 using medications have resulted in 30% reductions in mortality and morbidity. Although effective, nearly 70% of the morbidity and mortality from coronary artery disease (CAD) occurs in patients receiving lipid-lowering therapy, despite highly significant 30% to 35% low-density lipoprotein (LDL) level reductions. Additional interventions beyond medication-induced LDL reductions appear warranted if our health care system is to further reduce the morbidity, mortality, and expenses associated with CAD. Nutritional choices have been shown to beneficially influence several CAD risk factors.³

Physicians need low-cost, practical, and effective dietary programs that patients with CAD are willing to follow. In particular, there is a need to explore simple dietary interventions that influence the pathophysiology behind CAD. Fortunately, there is growing interest in dietary intake that has been shown to decrease LDL oxidation^4-7 and to improve endothelial vasomotion. For example, it has been shown in patients in France with known CAD that simply switching polyunsaturated fat intake to largely oxidation-stable monounsaturated fat intake and n-3 fatty acid intake (omega-3 fats) reduces total mortality by 70% without reductions in total fat intake or changes in lipid profiles.^9,10 Other observational studies have supported the concept that the type of fat intake is more important than reducing total fat intake.^11,12

The objectives of the Dietary Intervention and Evaluation Trial (D.I.E.T.) were to add healthy foods to the diet (eg, legumes, fruits, and vegetables) and to change dietary fat intake from polyunsaturated and saturated fat to oxidation-resistant monounsaturated fat and n-3 fatty acid sources. In essence, we assessed the willingness of Americans with CAD to move toward a more Mediterranean-like diet. The subjects were counseled during group office visits. The mechanism for physicians to offer group visits as a billable service is reviewed elsewhere.¹³

Methods

Study Sample

In January 1997, patients with CAD were selected from the Heart Care Registry at Group Health Cooperative at 4 multispecialty clinics in 3 cities. Inclusion criteria were known CAD (based on hospital-generated diagnostic coding data and a subsequent chart review confirmation) and either LDL levels greater than 3.4 mmol per L (130 mg/dL) or patients without an LDL level recorded in the previous 18 months but with a total cholesterol/high-density lipoprotein (HDL) ratio greater than 5.5. We enrolled patients with high lipid levels in an attempt to choose patients at the greatest need for intervention. The Center for Health Studies contacted 234 patients by telephone and successfully recruited 132 with known CAD to participate in our study (56% willingness to enroll). Primary care physicians excluded 11 patients with terminal or end-stage medical problems who were not likely to survive the duration of the study. One patient who was following another dietary program (the Ornish Program) was excluded, resulting in 120 remaining subjects. Anticipating a 15% greater reduction in LDL levels and a 15% greater improvement in dietary intake in the experimental group than the control group, it was determined this sample size (a=0.05) would have a power of 80 (b=0.20). The subjects gave informed consent to participate in this randomized trial, signed consent forms, and received free monthly classes over the course of 1 year. There was no monetary compensation for their participation. The Human Subjects Committee of the Center for Health Studies and the University of Washington Research Committee approved this project.

After the recruitment and consent we chose specific days for fasting blood draws and offered a specific evening at each clinic when group visits would be offered. Twenty-three of the 120 patients could not attend the group visits and blood draw sessions as scheduled, and for personal or scheduling reasons withdrew from the study. The remaining 97 patients (29.9% women) were stratified according to a single entry LDL level and then assigned using an alternating table to create 2 groups with equal LDL levels. The 2 groups were then randomly assigned as experimental and control groups. After this stratification based on LDL levels and random group assignment, we compared the ages, total cholesterol/HDL ratios, hemoglobin (Hb) A1C levels, triglyceride levels, blood pressures, and body mass indexes of the 2 groups and found them to be similar at entry Table 1. During the 1-year study, 4 of the 49 patients in the experimental group and 3 of the 48 patients in the control group dropped out for scheduling or personal reasons before completing the study. Thus, 45 experimental and 45 control subjects completed the trial.

The mean LDL levels for the entire study population decreased from 3.7 mmol per L (142 mg/dL) in January 1997, when the subjects were identified to 3.1 mmol per L (118.5 mg/dL) in September 1997, when they were randomized into groups. This LDL reduction was presumably because of a health maintenance organization–directed campaign to lower LDL levels in this heart care population with lipid-lowering medications. A single medication (simvastatin) accounted for 89% of the lipid-lowering medication used by these subjects. Despite prestudy LDL reductions, the majority of the patients recruited for the D.I.E.T intervention had not yet achieved a 35% LDL reduction.

Intervention

The experimental group met for 14 90-minute group visits over 1 year: weekly for the first month and then monthly. Classes taught by a licensed practical nurse highlighted an antioxidant-rich diet with a maximum of 20% of calories from fat, and encouraged the use of monounsaturated and n-3 fatty acid types of fat in lieu of saturated and polyunsaturated fats. The intervention patients also received a textbook (The 28-Day Antioxidant Diet Program) that included information for shopping lists, menu plans, and food-monitoring sheets. Additional recipes were added at the group’s request and were reviewed during the lectures. Cooking demonstrations were performed. A gradual increase in physical activities, such as walking, was also encouraged. Significant others were strongly encouraged to participate in these classes.

Specific intervention goals were aimed at increasing fruit and vegetable intake to 7 or more servings per day, adding garlic and antioxidant-rich herbs and 1 serving of a legume or soy product daily. The program emphasized choosing low-glycemic carbohydrate sources. Also, the intervention had a goal for each subject to exercise for 30 to 45 minutes 5 to 6 days per week and to reach a target heart rate 60% to 70% of their maximum predicted rate. Within the capitated health system where this intervention occurred, the cost for materials and personnel to continue these types of group visit sessions for CAD patients on an ongoing basis would be $7 (United States) per member per month (PMPM).

Patients in the control group were given written information that included a handout to follow the National Cholesterol Education Program’s Step II-III diet, a handout on choosing dietary fats, information on increasing produce and whole grain intake, and American Heart Association sample meal plans. The control group did not meet in group visits but continued to receive care as usual from their providers.

Members of both groups had their fasting lipids levels and Hb A1C levels drawn and compared at 0 and 12 months. All laboratory results were forwarded to the patients’ primary care physicians, who were strongly encouraged to treat elevated lipid levels with lifestyle-change recommendations and lipid-lowering medications until LDL levels reached a specific target: a 30% to 35% reduction in LDL from their pre-event LDL, or if the pre-event LDL was unavailable, a final LDL less than 2.6 mmol per L (100 mg/dL) or an LDL less than 3.4 mmol per L (130 mg/dL) and with a total cholesterol/HDL ratio less than 4.0.

Data Collection

Blood samples were collected at each clinic, and fasting lipid and Hb A1C samples were obtained. Thirty-day food frequency questionnaires from the Fred Hutchinson Women’s Health Initiative (WHI) were completed by study patients at 0, 3, and 12 months. An additional food intake questionnaire was given to assess both legume intake in servings per week and the type of fat used for cooking and baking.

PMPM expense data were obtained through patient-specific billing and utilization data. All of the subjects in our study were participants in a 100% capitated health care system. All office visits, pharmacy expenses, emergency department visits, and hospital admissions and procedures were tabulated. The expense data were categorized as total expenses, in-patient hospital care, pharmacy, and outpatient care. The $7 estimated to fund this program on an ongoing basis was added to the PMPM expenses of the experimental group.

Statistical Analysis

Differences between the experimental and control groups for fasting blood levels and PMPM expense data were assessed using a Student t test, both at entry and after 12 months. No statistical differences were noted between the control and experimental groups at entry. At entry and at 12 months we analyzed food intake questionnaires and laboratory results using an independent samples t test. Statistical analysis was performed using SAS software (SAS Institute, Inc, Cary, NC).

Results

Food Intake Questionnaires

Table 2 shows the mean fruit and vegetable intake for patients in the experimental group and those in the control group at entry and after 12 months. The experimental group patients increased their vegetable and fruit intake significantly compared with the control group over 12 months (P = .0001 and .0072, respectively).

The experimental group reduced their total fat intake and their saturated fat intake after 12 months; however, these differences in change were not significant (P=.4045, P=.1049).

Separate from the WHI food intake questionnaire, subjects were asked to report their weekly intake of legumes (a serving size was equal to 0.5 cup legumes) and the type of fat used for cooking and baking. The experimental group also reported a significant 45% increase in use of monounsaturated cooking oils compared with the control group’s 1% increase (P=.0001).

Fasting Blood Levels

Using a paired comparison t test, the experimental group noted a significant reduction in LDL levels, 117 mg per dL at entry to 104 mg per dL at 12 months (P=.0035,) while the control group’s LDL reduction was not significant, 119 mg per dL at entry and 111.7 mg per dL at 12 months (P=.1475). The difference in LDL reductions between the 2 groups was not significant by an independent samples t test. The total cholesterol/HDL ratio, Hb A1C, and triglyceride levels decreased for both groups; HDL increased for both groups, but the difference between the changes was not statistically significant.*

PMPM Expenses

Both groups noted reductions in PMPM total and in-patient expenses. The total PMPM expenses decreased 38% for the experimental group and 10% for the control group. No statistically significant differences were found between the groups’ total PMPM expenses (P=.2975).†

After the 1-year intervention, there was no difference in overall pharmacy PMPM expenses between the 2 groups (P=.4578). Specifically, lipid-lowering medication use and expense was very similar in the 2 groups before and after the intervention.

Discussion

In our small group of 97 patients with known CAD and elevated lipid levels, this intervention was not powered to yield significant improvements in clinical outcomes. Our study was associated with increased fruit and vegetable intake (nearly 2 more servings per day), a small increase in legume intake, and a switch to oxidation-resistant monounsaturated cooking oils.

Our study does help to confirm that half of patients with CAD are willing to make significant lifestyle changes when offered a program that emphasizes adding healthy foods in a group visit format. We also targeted patients with known CAD and elevated lipid levels and demonstrated that patients in the greatest need of therapy were willing to try lifestyle changes.

The experimental group noted significant reductions in LDL levels, but they were not statistically greater reductions than the control group. A bigger trend toward improvements in lipid and Hb A1C levels and reductions in total and saturated fat intake occurred in the experimental group than in the control group, yet these differences were not statistically significant. A 10% dropout rate was anticipated over the study; however, the additional 19% dropout rate that occurred after recruitment and before randomization was unexpected and limited the power to assess some of the trends we noted. The difference in LDL reductions between groups would have reached statistical significance if a limited reduction in LDL levels had occurred in the control group (<2%), or if the study had achieved the original target size planned and the changes noted persisted in the missing subjects.

The lipid reductions that occurred during our study may seem limited. However, this study reflects the ongoing implementation of various strategies over several years to improve lipid levels in this cohort that initially had LDL levels well above their target. In the 9-month time interval between identifying the patients and starting the intervention, LDL levels decreased by 16.5% in both groups, from a mean of 3.7 mmol per L (142 mg/dL) to 3.1 mmol per L (118.5 mg/dL).

PMPM statistical data is difficult to evaluate because of the well-known high variability in the cost of providing care to high-risk patients. No statistically significant differences were noted in total PMPM expenses between the groups in our study. The Cooperative Health Care Clinic Study²⁰ supports the idea that group visit interventions may reduce health care expenses while improving clinical outcomes. That study in Colorado was conducted using seniors with multiple medical problems and noted reduced PMPM expenses, as well as enhanced patient satisfaction, improved immunization rates, and reduced hospital admission rates.

Limitations

A limitation of this and many lifestyle intervention studies that are taught on the group level is that we cannot distinguish between the direct benefits of the lifestyle interventions and the indirect benefits of meeting within a group. A group visit itself is an intervention that may provide clinical benefits. These attributes include group support and improved adherence to lifestyle changes. More studies are needed to clarify the direct benefits of combining cohorts of patients with specific illnesses with the same intervention taught on an individual and a group visit level.

Additional limitations to our study are that the dietary results were self-reported and that all study participants would be expected to show a healthy participant effect. Although the control group did show a reduction in lipid profiles during our study, that group noted only a 3% decrease in total fat intake, no change in saturated fat intake, and a reduction in their vegetable, fruit, and legume intake. Thus, no significant dietary improvements were noted in the control group.

Conclusions

Patients with known CAD who are already being treated with lipid-lowering medication are willing to make dietary changes that are taught during group visits. More than 50% of inadequately controlled patients with known CAD who were offered our program were willing to enroll, and we achieved significant improvements in these patients in increased fruit and vegetable intake, legume intake, and in changing the type of fat use for cooking. In larger studies these improvements may prove to be associated with reductions in total health care expenses and in clinical events. Further studies are needed to test this type of group visit program with other patient populations in larger clinical settings.

Related Resources

• American Diabetes Association www.diabetes.org
• American Heart Association www.americanheart.org

Acknowledgments

This study was funded by the South Region Executive Committee at Group Health Cooperative of Puget Sound. The patient data registry was provided by Group Health’s Heart Care Team. Patient recruitment and sample size calculations were provided by Group Health’s Center for Health Studies. Fred Hutchinson’s Cancer Research Center provided food frequency questionnaires and performed the associated data analysis. The Geriatric Research Team at Morton Plant Mease Health Care in Clearwater, Florida, performed the remaining statistical data analysis.

It is well established that nearly half of all Americans will die of cardiovascular disease. Lipid-lowering trials^1,2 using medications have resulted in 30% reductions in mortality and morbidity. Although effective, nearly 70% of the morbidity and mortality from coronary artery disease (CAD) occurs in patients receiving lipid-lowering therapy, despite highly significant 30% to 35% low-density lipoprotein (LDL) level reductions. Additional interventions beyond medication-induced LDL reductions appear warranted if our health care system is to further reduce the morbidity, mortality, and expenses associated with CAD. Nutritional choices have been shown to beneficially influence several CAD risk factors.³

Physicians need low-cost, practical, and effective dietary programs that patients with CAD are willing to follow. In particular, there is a need to explore simple dietary interventions that influence the pathophysiology behind CAD. Fortunately, there is growing interest in dietary intake that has been shown to decrease LDL oxidation^4-7 and to improve endothelial vasomotion. For example, it has been shown in patients in France with known CAD that simply switching polyunsaturated fat intake to largely oxidation-stable monounsaturated fat intake and n-3 fatty acid intake (omega-3 fats) reduces total mortality by 70% without reductions in total fat intake or changes in lipid profiles.^9,10 Other observational studies have supported the concept that the type of fat intake is more important than reducing total fat intake.^11,12

The objectives of the Dietary Intervention and Evaluation Trial (D.I.E.T.) were to add healthy foods to the diet (eg, legumes, fruits, and vegetables) and to change dietary fat intake from polyunsaturated and saturated fat to oxidation-resistant monounsaturated fat and n-3 fatty acid sources. In essence, we assessed the willingness of Americans with CAD to move toward a more Mediterranean-like diet. The subjects were counseled during group office visits. The mechanism for physicians to offer group visits as a billable service is reviewed elsewhere.¹³

Methods

Study Sample

In January 1997, patients with CAD were selected from the Heart Care Registry at Group Health Cooperative at 4 multispecialty clinics in 3 cities. Inclusion criteria were known CAD (based on hospital-generated diagnostic coding data and a subsequent chart review confirmation) and either LDL levels greater than 3.4 mmol per L (130 mg/dL) or patients without an LDL level recorded in the previous 18 months but with a total cholesterol/high-density lipoprotein (HDL) ratio greater than 5.5. We enrolled patients with high lipid levels in an attempt to choose patients at the greatest need for intervention. The Center for Health Studies contacted 234 patients by telephone and successfully recruited 132 with known CAD to participate in our study (56% willingness to enroll). Primary care physicians excluded 11 patients with terminal or end-stage medical problems who were not likely to survive the duration of the study. One patient who was following another dietary program (the Ornish Program) was excluded, resulting in 120 remaining subjects. Anticipating a 15% greater reduction in LDL levels and a 15% greater improvement in dietary intake in the experimental group than the control group, it was determined this sample size (a=0.05) would have a power of 80 (b=0.20). The subjects gave informed consent to participate in this randomized trial, signed consent forms, and received free monthly classes over the course of 1 year. There was no monetary compensation for their participation. The Human Subjects Committee of the Center for Health Studies and the University of Washington Research Committee approved this project.

After the recruitment and consent we chose specific days for fasting blood draws and offered a specific evening at each clinic when group visits would be offered. Twenty-three of the 120 patients could not attend the group visits and blood draw sessions as scheduled, and for personal or scheduling reasons withdrew from the study. The remaining 97 patients (29.9% women) were stratified according to a single entry LDL level and then assigned using an alternating table to create 2 groups with equal LDL levels. The 2 groups were then randomly assigned as experimental and control groups. After this stratification based on LDL levels and random group assignment, we compared the ages, total cholesterol/HDL ratios, hemoglobin (Hb) A1C levels, triglyceride levels, blood pressures, and body mass indexes of the 2 groups and found them to be similar at entry Table 1. During the 1-year study, 4 of the 49 patients in the experimental group and 3 of the 48 patients in the control group dropped out for scheduling or personal reasons before completing the study. Thus, 45 experimental and 45 control subjects completed the trial.

The mean LDL levels for the entire study population decreased from 3.7 mmol per L (142 mg/dL) in January 1997, when the subjects were identified to 3.1 mmol per L (118.5 mg/dL) in September 1997, when they were randomized into groups. This LDL reduction was presumably because of a health maintenance organization–directed campaign to lower LDL levels in this heart care population with lipid-lowering medications. A single medication (simvastatin) accounted for 89% of the lipid-lowering medication used by these subjects. Despite prestudy LDL reductions, the majority of the patients recruited for the D.I.E.T intervention had not yet achieved a 35% LDL reduction.

Intervention

The experimental group met for 14 90-minute group visits over 1 year: weekly for the first month and then monthly. Classes taught by a licensed practical nurse highlighted an antioxidant-rich diet with a maximum of 20% of calories from fat, and encouraged the use of monounsaturated and n-3 fatty acid types of fat in lieu of saturated and polyunsaturated fats. The intervention patients also received a textbook (The 28-Day Antioxidant Diet Program) that included information for shopping lists, menu plans, and food-monitoring sheets. Additional recipes were added at the group’s request and were reviewed during the lectures. Cooking demonstrations were performed. A gradual increase in physical activities, such as walking, was also encouraged. Significant others were strongly encouraged to participate in these classes.

Specific intervention goals were aimed at increasing fruit and vegetable intake to 7 or more servings per day, adding garlic and antioxidant-rich herbs and 1 serving of a legume or soy product daily. The program emphasized choosing low-glycemic carbohydrate sources. Also, the intervention had a goal for each subject to exercise for 30 to 45 minutes 5 to 6 days per week and to reach a target heart rate 60% to 70% of their maximum predicted rate. Within the capitated health system where this intervention occurred, the cost for materials and personnel to continue these types of group visit sessions for CAD patients on an ongoing basis would be $7 (United States) per member per month (PMPM).

Patients in the control group were given written information that included a handout to follow the National Cholesterol Education Program’s Step II-III diet, a handout on choosing dietary fats, information on increasing produce and whole grain intake, and American Heart Association sample meal plans. The control group did not meet in group visits but continued to receive care as usual from their providers.

Members of both groups had their fasting lipids levels and Hb A1C levels drawn and compared at 0 and 12 months. All laboratory results were forwarded to the patients’ primary care physicians, who were strongly encouraged to treat elevated lipid levels with lifestyle-change recommendations and lipid-lowering medications until LDL levels reached a specific target: a 30% to 35% reduction in LDL from their pre-event LDL, or if the pre-event LDL was unavailable, a final LDL less than 2.6 mmol per L (100 mg/dL) or an LDL less than 3.4 mmol per L (130 mg/dL) and with a total cholesterol/HDL ratio less than 4.0.

Data Collection

Blood samples were collected at each clinic, and fasting lipid and Hb A1C samples were obtained. Thirty-day food frequency questionnaires from the Fred Hutchinson Women’s Health Initiative (WHI) were completed by study patients at 0, 3, and 12 months. An additional food intake questionnaire was given to assess both legume intake in servings per week and the type of fat used for cooking and baking.

PMPM expense data were obtained through patient-specific billing and utilization data. All of the subjects in our study were participants in a 100% capitated health care system. All office visits, pharmacy expenses, emergency department visits, and hospital admissions and procedures were tabulated. The expense data were categorized as total expenses, in-patient hospital care, pharmacy, and outpatient care. The $7 estimated to fund this program on an ongoing basis was added to the PMPM expenses of the experimental group.

Statistical Analysis

Differences between the experimental and control groups for fasting blood levels and PMPM expense data were assessed using a Student t test, both at entry and after 12 months. No statistical differences were noted between the control and experimental groups at entry. At entry and at 12 months we analyzed food intake questionnaires and laboratory results using an independent samples t test. Statistical analysis was performed using SAS software (SAS Institute, Inc, Cary, NC).

Results

Food Intake Questionnaires

Table 2 shows the mean fruit and vegetable intake for patients in the experimental group and those in the control group at entry and after 12 months. The experimental group patients increased their vegetable and fruit intake significantly compared with the control group over 12 months (P = .0001 and .0072, respectively).

The experimental group reduced their total fat intake and their saturated fat intake after 12 months; however, these differences in change were not significant (P=.4045, P=.1049).

Separate from the WHI food intake questionnaire, subjects were asked to report their weekly intake of legumes (a serving size was equal to 0.5 cup legumes) and the type of fat used for cooking and baking. The experimental group also reported a significant 45% increase in use of monounsaturated cooking oils compared with the control group’s 1% increase (P=.0001).

Fasting Blood Levels

Using a paired comparison t test, the experimental group noted a significant reduction in LDL levels, 117 mg per dL at entry to 104 mg per dL at 12 months (P=.0035,) while the control group’s LDL reduction was not significant, 119 mg per dL at entry and 111.7 mg per dL at 12 months (P=.1475). The difference in LDL reductions between the 2 groups was not significant by an independent samples t test. The total cholesterol/HDL ratio, Hb A1C, and triglyceride levels decreased for both groups; HDL increased for both groups, but the difference between the changes was not statistically significant.*

PMPM Expenses

Both groups noted reductions in PMPM total and in-patient expenses. The total PMPM expenses decreased 38% for the experimental group and 10% for the control group. No statistically significant differences were found between the groups’ total PMPM expenses (P=.2975).†

After the 1-year intervention, there was no difference in overall pharmacy PMPM expenses between the 2 groups (P=.4578). Specifically, lipid-lowering medication use and expense was very similar in the 2 groups before and after the intervention.

Discussion

In our small group of 97 patients with known CAD and elevated lipid levels, this intervention was not powered to yield significant improvements in clinical outcomes. Our study was associated with increased fruit and vegetable intake (nearly 2 more servings per day), a small increase in legume intake, and a switch to oxidation-resistant monounsaturated cooking oils.

Our study does help to confirm that half of patients with CAD are willing to make significant lifestyle changes when offered a program that emphasizes adding healthy foods in a group visit format. We also targeted patients with known CAD and elevated lipid levels and demonstrated that patients in the greatest need of therapy were willing to try lifestyle changes.

The experimental group noted significant reductions in LDL levels, but they were not statistically greater reductions than the control group. A bigger trend toward improvements in lipid and Hb A1C levels and reductions in total and saturated fat intake occurred in the experimental group than in the control group, yet these differences were not statistically significant. A 10% dropout rate was anticipated over the study; however, the additional 19% dropout rate that occurred after recruitment and before randomization was unexpected and limited the power to assess some of the trends we noted. The difference in LDL reductions between groups would have reached statistical significance if a limited reduction in LDL levels had occurred in the control group (<2%), or if the study had achieved the original target size planned and the changes noted persisted in the missing subjects.

The lipid reductions that occurred during our study may seem limited. However, this study reflects the ongoing implementation of various strategies over several years to improve lipid levels in this cohort that initially had LDL levels well above their target. In the 9-month time interval between identifying the patients and starting the intervention, LDL levels decreased by 16.5% in both groups, from a mean of 3.7 mmol per L (142 mg/dL) to 3.1 mmol per L (118.5 mg/dL).

PMPM statistical data is difficult to evaluate because of the well-known high variability in the cost of providing care to high-risk patients. No statistically significant differences were noted in total PMPM expenses between the groups in our study. The Cooperative Health Care Clinic Study²⁰ supports the idea that group visit interventions may reduce health care expenses while improving clinical outcomes. That study in Colorado was conducted using seniors with multiple medical problems and noted reduced PMPM expenses, as well as enhanced patient satisfaction, improved immunization rates, and reduced hospital admission rates.

Limitations

A limitation of this and many lifestyle intervention studies that are taught on the group level is that we cannot distinguish between the direct benefits of the lifestyle interventions and the indirect benefits of meeting within a group. A group visit itself is an intervention that may provide clinical benefits. These attributes include group support and improved adherence to lifestyle changes. More studies are needed to clarify the direct benefits of combining cohorts of patients with specific illnesses with the same intervention taught on an individual and a group visit level.

Additional limitations to our study are that the dietary results were self-reported and that all study participants would be expected to show a healthy participant effect. Although the control group did show a reduction in lipid profiles during our study, that group noted only a 3% decrease in total fat intake, no change in saturated fat intake, and a reduction in their vegetable, fruit, and legume intake. Thus, no significant dietary improvements were noted in the control group.

Conclusions

Patients with known CAD who are already being treated with lipid-lowering medication are willing to make dietary changes that are taught during group visits. More than 50% of inadequately controlled patients with known CAD who were offered our program were willing to enroll, and we achieved significant improvements in these patients in increased fruit and vegetable intake, legume intake, and in changing the type of fat use for cooking. In larger studies these improvements may prove to be associated with reductions in total health care expenses and in clinical events. Further studies are needed to test this type of group visit program with other patient populations in larger clinical settings.

Related Resources

• American Diabetes Association www.diabetes.org
• American Heart Association www.americanheart.org

Acknowledgments

This study was funded by the South Region Executive Committee at Group Health Cooperative of Puget Sound. The patient data registry was provided by Group Health’s Heart Care Team. Patient recruitment and sample size calculations were provided by Group Health’s Center for Health Studies. Fred Hutchinson’s Cancer Research Center provided food frequency questionnaires and performed the associated data analysis. The Geriatric Research Team at Morton Plant Mease Health Care in Clearwater, Florida, performed the remaining statistical data analysis.

It is well established that nearly half of all Americans will die of cardiovascular disease. Lipid-lowering trials^1,2 using medications have resulted in 30% reductions in mortality and morbidity. Although effective, nearly 70% of the morbidity and mortality from coronary artery disease (CAD) occurs in patients receiving lipid-lowering therapy, despite highly significant 30% to 35% low-density lipoprotein (LDL) level reductions. Additional interventions beyond medication-induced LDL reductions appear warranted if our health care system is to further reduce the morbidity, mortality, and expenses associated with CAD. Nutritional choices have been shown to beneficially influence several CAD risk factors.³

Physicians need low-cost, practical, and effective dietary programs that patients with CAD are willing to follow. In particular, there is a need to explore simple dietary interventions that influence the pathophysiology behind CAD. Fortunately, there is growing interest in dietary intake that has been shown to decrease LDL oxidation^4-7 and to improve endothelial vasomotion. For example, it has been shown in patients in France with known CAD that simply switching polyunsaturated fat intake to largely oxidation-stable monounsaturated fat intake and n-3 fatty acid intake (omega-3 fats) reduces total mortality by 70% without reductions in total fat intake or changes in lipid profiles.^9,10 Other observational studies have supported the concept that the type of fat intake is more important than reducing total fat intake.^11,12

The objectives of the Dietary Intervention and Evaluation Trial (D.I.E.T.) were to add healthy foods to the diet (eg, legumes, fruits, and vegetables) and to change dietary fat intake from polyunsaturated and saturated fat to oxidation-resistant monounsaturated fat and n-3 fatty acid sources. In essence, we assessed the willingness of Americans with CAD to move toward a more Mediterranean-like diet. The subjects were counseled during group office visits. The mechanism for physicians to offer group visits as a billable service is reviewed elsewhere.¹³

Methods

Study Sample

In January 1997, patients with CAD were selected from the Heart Care Registry at Group Health Cooperative at 4 multispecialty clinics in 3 cities. Inclusion criteria were known CAD (based on hospital-generated diagnostic coding data and a subsequent chart review confirmation) and either LDL levels greater than 3.4 mmol per L (130 mg/dL) or patients without an LDL level recorded in the previous 18 months but with a total cholesterol/high-density lipoprotein (HDL) ratio greater than 5.5. We enrolled patients with high lipid levels in an attempt to choose patients at the greatest need for intervention. The Center for Health Studies contacted 234 patients by telephone and successfully recruited 132 with known CAD to participate in our study (56% willingness to enroll). Primary care physicians excluded 11 patients with terminal or end-stage medical problems who were not likely to survive the duration of the study. One patient who was following another dietary program (the Ornish Program) was excluded, resulting in 120 remaining subjects. Anticipating a 15% greater reduction in LDL levels and a 15% greater improvement in dietary intake in the experimental group than the control group, it was determined this sample size (a=0.05) would have a power of 80 (b=0.20). The subjects gave informed consent to participate in this randomized trial, signed consent forms, and received free monthly classes over the course of 1 year. There was no monetary compensation for their participation. The Human Subjects Committee of the Center for Health Studies and the University of Washington Research Committee approved this project.

After the recruitment and consent we chose specific days for fasting blood draws and offered a specific evening at each clinic when group visits would be offered. Twenty-three of the 120 patients could not attend the group visits and blood draw sessions as scheduled, and for personal or scheduling reasons withdrew from the study. The remaining 97 patients (29.9% women) were stratified according to a single entry LDL level and then assigned using an alternating table to create 2 groups with equal LDL levels. The 2 groups were then randomly assigned as experimental and control groups. After this stratification based on LDL levels and random group assignment, we compared the ages, total cholesterol/HDL ratios, hemoglobin (Hb) A1C levels, triglyceride levels, blood pressures, and body mass indexes of the 2 groups and found them to be similar at entry Table 1. During the 1-year study, 4 of the 49 patients in the experimental group and 3 of the 48 patients in the control group dropped out for scheduling or personal reasons before completing the study. Thus, 45 experimental and 45 control subjects completed the trial.

The mean LDL levels for the entire study population decreased from 3.7 mmol per L (142 mg/dL) in January 1997, when the subjects were identified to 3.1 mmol per L (118.5 mg/dL) in September 1997, when they were randomized into groups. This LDL reduction was presumably because of a health maintenance organization–directed campaign to lower LDL levels in this heart care population with lipid-lowering medications. A single medication (simvastatin) accounted for 89% of the lipid-lowering medication used by these subjects. Despite prestudy LDL reductions, the majority of the patients recruited for the D.I.E.T intervention had not yet achieved a 35% LDL reduction.

Intervention

The experimental group met for 14 90-minute group visits over 1 year: weekly for the first month and then monthly. Classes taught by a licensed practical nurse highlighted an antioxidant-rich diet with a maximum of 20% of calories from fat, and encouraged the use of monounsaturated and n-3 fatty acid types of fat in lieu of saturated and polyunsaturated fats. The intervention patients also received a textbook (The 28-Day Antioxidant Diet Program) that included information for shopping lists, menu plans, and food-monitoring sheets. Additional recipes were added at the group’s request and were reviewed during the lectures. Cooking demonstrations were performed. A gradual increase in physical activities, such as walking, was also encouraged. Significant others were strongly encouraged to participate in these classes.

Specific intervention goals were aimed at increasing fruit and vegetable intake to 7 or more servings per day, adding garlic and antioxidant-rich herbs and 1 serving of a legume or soy product daily. The program emphasized choosing low-glycemic carbohydrate sources. Also, the intervention had a goal for each subject to exercise for 30 to 45 minutes 5 to 6 days per week and to reach a target heart rate 60% to 70% of their maximum predicted rate. Within the capitated health system where this intervention occurred, the cost for materials and personnel to continue these types of group visit sessions for CAD patients on an ongoing basis would be $7 (United States) per member per month (PMPM).

Patients in the control group were given written information that included a handout to follow the National Cholesterol Education Program’s Step II-III diet, a handout on choosing dietary fats, information on increasing produce and whole grain intake, and American Heart Association sample meal plans. The control group did not meet in group visits but continued to receive care as usual from their providers.

Members of both groups had their fasting lipids levels and Hb A1C levels drawn and compared at 0 and 12 months. All laboratory results were forwarded to the patients’ primary care physicians, who were strongly encouraged to treat elevated lipid levels with lifestyle-change recommendations and lipid-lowering medications until LDL levels reached a specific target: a 30% to 35% reduction in LDL from their pre-event LDL, or if the pre-event LDL was unavailable, a final LDL less than 2.6 mmol per L (100 mg/dL) or an LDL less than 3.4 mmol per L (130 mg/dL) and with a total cholesterol/HDL ratio less than 4.0.

Data Collection

Blood samples were collected at each clinic, and fasting lipid and Hb A1C samples were obtained. Thirty-day food frequency questionnaires from the Fred Hutchinson Women’s Health Initiative (WHI) were completed by study patients at 0, 3, and 12 months. An additional food intake questionnaire was given to assess both legume intake in servings per week and the type of fat used for cooking and baking.

PMPM expense data were obtained through patient-specific billing and utilization data. All of the subjects in our study were participants in a 100% capitated health care system. All office visits, pharmacy expenses, emergency department visits, and hospital admissions and procedures were tabulated. The expense data were categorized as total expenses, in-patient hospital care, pharmacy, and outpatient care. The $7 estimated to fund this program on an ongoing basis was added to the PMPM expenses of the experimental group.

Statistical Analysis

Differences between the experimental and control groups for fasting blood levels and PMPM expense data were assessed using a Student t test, both at entry and after 12 months. No statistical differences were noted between the control and experimental groups at entry. At entry and at 12 months we analyzed food intake questionnaires and laboratory results using an independent samples t test. Statistical analysis was performed using SAS software (SAS Institute, Inc, Cary, NC).

Results

Food Intake Questionnaires

Table 2 shows the mean fruit and vegetable intake for patients in the experimental group and those in the control group at entry and after 12 months. The experimental group patients increased their vegetable and fruit intake significantly compared with the control group over 12 months (P = .0001 and .0072, respectively).

The experimental group reduced their total fat intake and their saturated fat intake after 12 months; however, these differences in change were not significant (P=.4045, P=.1049).

Separate from the WHI food intake questionnaire, subjects were asked to report their weekly intake of legumes (a serving size was equal to 0.5 cup legumes) and the type of fat used for cooking and baking. The experimental group also reported a significant 45% increase in use of monounsaturated cooking oils compared with the control group’s 1% increase (P=.0001).

Fasting Blood Levels

Using a paired comparison t test, the experimental group noted a significant reduction in LDL levels, 117 mg per dL at entry to 104 mg per dL at 12 months (P=.0035,) while the control group’s LDL reduction was not significant, 119 mg per dL at entry and 111.7 mg per dL at 12 months (P=.1475). The difference in LDL reductions between the 2 groups was not significant by an independent samples t test. The total cholesterol/HDL ratio, Hb A1C, and triglyceride levels decreased for both groups; HDL increased for both groups, but the difference between the changes was not statistically significant.*

PMPM Expenses

Both groups noted reductions in PMPM total and in-patient expenses. The total PMPM expenses decreased 38% for the experimental group and 10% for the control group. No statistically significant differences were found between the groups’ total PMPM expenses (P=.2975).†

After the 1-year intervention, there was no difference in overall pharmacy PMPM expenses between the 2 groups (P=.4578). Specifically, lipid-lowering medication use and expense was very similar in the 2 groups before and after the intervention.

Discussion

In our small group of 97 patients with known CAD and elevated lipid levels, this intervention was not powered to yield significant improvements in clinical outcomes. Our study was associated with increased fruit and vegetable intake (nearly 2 more servings per day), a small increase in legume intake, and a switch to oxidation-resistant monounsaturated cooking oils.

Our study does help to confirm that half of patients with CAD are willing to make significant lifestyle changes when offered a program that emphasizes adding healthy foods in a group visit format. We also targeted patients with known CAD and elevated lipid levels and demonstrated that patients in the greatest need of therapy were willing to try lifestyle changes.

The experimental group noted significant reductions in LDL levels, but they were not statistically greater reductions than the control group. A bigger trend toward improvements in lipid and Hb A1C levels and reductions in total and saturated fat intake occurred in the experimental group than in the control group, yet these differences were not statistically significant. A 10% dropout rate was anticipated over the study; however, the additional 19% dropout rate that occurred after recruitment and before randomization was unexpected and limited the power to assess some of the trends we noted. The difference in LDL reductions between groups would have reached statistical significance if a limited reduction in LDL levels had occurred in the control group (<2%), or if the study had achieved the original target size planned and the changes noted persisted in the missing subjects.

The lipid reductions that occurred during our study may seem limited. However, this study reflects the ongoing implementation of various strategies over several years to improve lipid levels in this cohort that initially had LDL levels well above their target. In the 9-month time interval between identifying the patients and starting the intervention, LDL levels decreased by 16.5% in both groups, from a mean of 3.7 mmol per L (142 mg/dL) to 3.1 mmol per L (118.5 mg/dL).

PMPM statistical data is difficult to evaluate because of the well-known high variability in the cost of providing care to high-risk patients. No statistically significant differences were noted in total PMPM expenses between the groups in our study. The Cooperative Health Care Clinic Study²⁰ supports the idea that group visit interventions may reduce health care expenses while improving clinical outcomes. That study in Colorado was conducted using seniors with multiple medical problems and noted reduced PMPM expenses, as well as enhanced patient satisfaction, improved immunization rates, and reduced hospital admission rates.

Limitations

A limitation of this and many lifestyle intervention studies that are taught on the group level is that we cannot distinguish between the direct benefits of the lifestyle interventions and the indirect benefits of meeting within a group. A group visit itself is an intervention that may provide clinical benefits. These attributes include group support and improved adherence to lifestyle changes. More studies are needed to clarify the direct benefits of combining cohorts of patients with specific illnesses with the same intervention taught on an individual and a group visit level.

Additional limitations to our study are that the dietary results were self-reported and that all study participants would be expected to show a healthy participant effect. Although the control group did show a reduction in lipid profiles during our study, that group noted only a 3% decrease in total fat intake, no change in saturated fat intake, and a reduction in their vegetable, fruit, and legume intake. Thus, no significant dietary improvements were noted in the control group.

Conclusions

Patients with known CAD who are already being treated with lipid-lowering medication are willing to make dietary changes that are taught during group visits. More than 50% of inadequately controlled patients with known CAD who were offered our program were willing to enroll, and we achieved significant improvements in these patients in increased fruit and vegetable intake, legume intake, and in changing the type of fat use for cooking. In larger studies these improvements may prove to be associated with reductions in total health care expenses and in clinical events. Further studies are needed to test this type of group visit program with other patient populations in larger clinical settings.

Related Resources

• American Diabetes Association www.diabetes.org
• American Heart Association www.americanheart.org

Acknowledgments

This study was funded by the South Region Executive Committee at Group Health Cooperative of Puget Sound. The patient data registry was provided by Group Health’s Heart Care Team. Patient recruitment and sample size calculations were provided by Group Health’s Center for Health Studies. Fred Hutchinson’s Cancer Research Center provided food frequency questionnaires and performed the associated data analysis. The Geriatric Research Team at Morton Plant Mease Health Care in Clearwater, Florida, performed the remaining statistical data analysis.