Blood Cultures in Nonpneumonia Illness

In 2002, based on consensus practice guidelines,[1] the Centers for Medicare and Medicaid Services (CMS) and the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) announced a core measure mandating the collection of routine blood cultures in the emergency department (ED) for all patients hospitalized with community‐acquired pneumonia (CAP) to benchmark the quality of hospital care. However, due to the limited utility and false‐positive results of routine blood cultures,[2, 3, 4, 5, 6] performance measures and practice guidelines were modified in 2005 and 2007, respectively, to recommend routine collection in only the sickest patients with CAP.[2, 7] Despite recommendations for a more narrow set of indications, the collection of blood cultures in patients hospitalized with CAP continued to increase.[8]

Distinguishing CAP from other respiratory illnesses may be challenging. Among patients presenting to the ED with an acute respiratory illness, only a minority of patients (10%30%) are diagnosed with pneumonia.[9] Therefore, the harms and costs of inappropriate diagnostic tests for CAP may be further magnified if applied to a larger population of patients who present to the ED with similar clinical signs and symptoms as pneumonia. Using a national sample of ED visits, we examined whether there was a similar increase in the frequency of blood culture collection among patients who were hospitalized with respiratory symptoms due to an illness other than pneumonia.

METHOD

RESULTS

This study included 4854 ED visits, representing approximately 17 million visits by adult patients hospitalized with respiratory symptoms due to a nonpneumonia illness. The most common primary ED provider's diagnoses for these visits included heart failure (15.9%), chronic obstructive pulmonary disease (12.6%), chest pain (11.9%), respiratory insufficiency or failure (8.8%), and asthma (5.5%). The characteristics of these visits are shown in Table 1.

The proportion of blood cultures collected in the ED for patients hospitalized with respiratory symptoms due to a nonpneumonia illness increased from 9.9% (95% confidence interval [CI]: 7.1%‐13.5%) in 2002 to 20.4% (95% CI: 16.1%‐25.6%) in 2010 (P<0.001 for the trend). This observed increase paralleled the increase in the frequency of culture collection in patients hospitalized with CAP (P=0.12 for the difference in temporal trends). The estimated absolute number of visits for respiratory symptoms due a nonpneumonia illness with a blood culture collected increased from 211,000 (95% CI: 126,000296,000) in 2002 to 526,000 (95% CI: 361,000692,000) in 2010, which was similar in magnitude to the estimated number of visits for CAP with a culture collected (Table 2).

DISCUSSION

In this national study of ED visits, we found that the collection of blood cultures in patients hospitalized with respiratory symptoms due to an illness other than pneumonia continued to increase from 2002 to 2010 in a parallel fashion to the trend observed for patients hospitalized with CAP. Our findings suggest that the heightened attention of collecting blood cultures for suspected pneumonia had unintended consequences, which led to an increase in the collection of blood cultures in patients hospitalized with conditions that mimic pneumonia in the ED.

There can be a great deal of diagnostic uncertainty when treating patients in the ED who present with acute respiratory symptoms. Unfortunately, the initial history and physical exam are often insufficient to effectively rule in CAP.[13] Furthermore, the challenge of diagnosing pneumonia is amplified in the subset of patients who present with evolving, atypical, or occult disease. Faced with this diagnostic uncertainty, ED providers may feel pressured to comply with performance measures for CAP, promoting the overuse of inappropriate diagnostic tests and treatments. For instance, efforts to comply with early antibiotic administration in patients with CAP have led to an increase in unnecessary antibiotic use among patients with a diagnosis other than CAP.[14] Due to concerns for these unintended consequences, the core measure for early antibiotic administration was effectively retired in 2012.

Although a smaller percentage of ED visits for respiratory symptoms had a blood culture collected compared to CAP visits, there was a similar absolute number of visits with a blood culture collected during the study period. While a fraction of these patients may present with an infectious etiology aside from pneumonia, the majority of these cases likely represent situations where blood cultures add little diagnostic value at the expense of potentially longer hospital stays and broad spectrum antimicrobial use due to false‐positive results,[5, 15] as well as higher costs incurred by the test itself.[15, 16]

Although recommendations for routine culture collection for all patients hospitalized with CAP have been revised, the JCAHO/CMS core measure (PN‐3b) announced in 2002 mandates that if a culture is collected in the ED, it should be collected prior to antibiotic administration. Due to inherent uncertainty and challenges in making a timely diagnosis of pneumonia, this measure may encourage providers to reflexively order cultures in all patients presenting with respiratory symptoms in whom antibiotic administration is anticipated. The observed increasing trend in culture collection in patients hospitalized with respiratory symptoms due to a nonpneumonia illness should prompt JCAHO and CMS to reevaluate the risks and benefits of this core measure, with consideration of eliminating it altogether to discourage overuse in this population.

Our study had certain limitations. First, the omission of 2005 and 2006 data prohibited an evaluation of whether culture rates slowed down among patients hospitalized with respiratory symptoms due to a nonpneumonia illness after revisions in recommendations for obtaining cultures in patients with CAP. Second, there may have been misclassification of culture collection due to errors in chart abstraction. However, abstraction errors in the NHAMCS typically result in undercoding.[17] Therefore, our findings likely underestimate the magnitude and frequency of culture collection in this population.

In conclusion, collecting blood cultures in the ED for patients hospitalized with respiratory symptoms due to a nonpneumonia illness has increased in a parallel fashion compared to the trend in culture collection in patients hospitalized with CAP from 2002 to 2010. This suggests an important potential unintended consequence of blood culture recommendations for CAP on patients who present with conditions that resemble pneumonia. More attention to the judicious use of blood cultures in these patients to reduce harm and costs is needed.

In 2002, based on consensus practice guidelines,[1] the Centers for Medicare and Medicaid Services (CMS) and the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) announced a core measure mandating the collection of routine blood cultures in the emergency department (ED) for all patients hospitalized with community‐acquired pneumonia (CAP) to benchmark the quality of hospital care. However, due to the limited utility and false‐positive results of routine blood cultures,[2, 3, 4, 5, 6] performance measures and practice guidelines were modified in 2005 and 2007, respectively, to recommend routine collection in only the sickest patients with CAP.[2, 7] Despite recommendations for a more narrow set of indications, the collection of blood cultures in patients hospitalized with CAP continued to increase.[8]

Distinguishing CAP from other respiratory illnesses may be challenging. Among patients presenting to the ED with an acute respiratory illness, only a minority of patients (10%30%) are diagnosed with pneumonia.[9] Therefore, the harms and costs of inappropriate diagnostic tests for CAP may be further magnified if applied to a larger population of patients who present to the ED with similar clinical signs and symptoms as pneumonia. Using a national sample of ED visits, we examined whether there was a similar increase in the frequency of blood culture collection among patients who were hospitalized with respiratory symptoms due to an illness other than pneumonia.

METHOD

RESULTS

This study included 4854 ED visits, representing approximately 17 million visits by adult patients hospitalized with respiratory symptoms due to a nonpneumonia illness. The most common primary ED provider's diagnoses for these visits included heart failure (15.9%), chronic obstructive pulmonary disease (12.6%), chest pain (11.9%), respiratory insufficiency or failure (8.8%), and asthma (5.5%). The characteristics of these visits are shown in Table 1.

The proportion of blood cultures collected in the ED for patients hospitalized with respiratory symptoms due to a nonpneumonia illness increased from 9.9% (95% confidence interval [CI]: 7.1%‐13.5%) in 2002 to 20.4% (95% CI: 16.1%‐25.6%) in 2010 (P<0.001 for the trend). This observed increase paralleled the increase in the frequency of culture collection in patients hospitalized with CAP (P=0.12 for the difference in temporal trends). The estimated absolute number of visits for respiratory symptoms due a nonpneumonia illness with a blood culture collected increased from 211,000 (95% CI: 126,000296,000) in 2002 to 526,000 (95% CI: 361,000692,000) in 2010, which was similar in magnitude to the estimated number of visits for CAP with a culture collected (Table 2).

DISCUSSION

In this national study of ED visits, we found that the collection of blood cultures in patients hospitalized with respiratory symptoms due to an illness other than pneumonia continued to increase from 2002 to 2010 in a parallel fashion to the trend observed for patients hospitalized with CAP. Our findings suggest that the heightened attention of collecting blood cultures for suspected pneumonia had unintended consequences, which led to an increase in the collection of blood cultures in patients hospitalized with conditions that mimic pneumonia in the ED.

There can be a great deal of diagnostic uncertainty when treating patients in the ED who present with acute respiratory symptoms. Unfortunately, the initial history and physical exam are often insufficient to effectively rule in CAP.[13] Furthermore, the challenge of diagnosing pneumonia is amplified in the subset of patients who present with evolving, atypical, or occult disease. Faced with this diagnostic uncertainty, ED providers may feel pressured to comply with performance measures for CAP, promoting the overuse of inappropriate diagnostic tests and treatments. For instance, efforts to comply with early antibiotic administration in patients with CAP have led to an increase in unnecessary antibiotic use among patients with a diagnosis other than CAP.[14] Due to concerns for these unintended consequences, the core measure for early antibiotic administration was effectively retired in 2012.

Although a smaller percentage of ED visits for respiratory symptoms had a blood culture collected compared to CAP visits, there was a similar absolute number of visits with a blood culture collected during the study period. While a fraction of these patients may present with an infectious etiology aside from pneumonia, the majority of these cases likely represent situations where blood cultures add little diagnostic value at the expense of potentially longer hospital stays and broad spectrum antimicrobial use due to false‐positive results,[5, 15] as well as higher costs incurred by the test itself.[15, 16]

Although recommendations for routine culture collection for all patients hospitalized with CAP have been revised, the JCAHO/CMS core measure (PN‐3b) announced in 2002 mandates that if a culture is collected in the ED, it should be collected prior to antibiotic administration. Due to inherent uncertainty and challenges in making a timely diagnosis of pneumonia, this measure may encourage providers to reflexively order cultures in all patients presenting with respiratory symptoms in whom antibiotic administration is anticipated. The observed increasing trend in culture collection in patients hospitalized with respiratory symptoms due to a nonpneumonia illness should prompt JCAHO and CMS to reevaluate the risks and benefits of this core measure, with consideration of eliminating it altogether to discourage overuse in this population.

Our study had certain limitations. First, the omission of 2005 and 2006 data prohibited an evaluation of whether culture rates slowed down among patients hospitalized with respiratory symptoms due to a nonpneumonia illness after revisions in recommendations for obtaining cultures in patients with CAP. Second, there may have been misclassification of culture collection due to errors in chart abstraction. However, abstraction errors in the NHAMCS typically result in undercoding.[17] Therefore, our findings likely underestimate the magnitude and frequency of culture collection in this population.

In conclusion, collecting blood cultures in the ED for patients hospitalized with respiratory symptoms due to a nonpneumonia illness has increased in a parallel fashion compared to the trend in culture collection in patients hospitalized with CAP from 2002 to 2010. This suggests an important potential unintended consequence of blood culture recommendations for CAP on patients who present with conditions that resemble pneumonia. More attention to the judicious use of blood cultures in these patients to reduce harm and costs is needed.

In 2002, based on consensus practice guidelines,[1] the Centers for Medicare and Medicaid Services (CMS) and the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) announced a core measure mandating the collection of routine blood cultures in the emergency department (ED) for all patients hospitalized with community‐acquired pneumonia (CAP) to benchmark the quality of hospital care. However, due to the limited utility and false‐positive results of routine blood cultures,[2, 3, 4, 5, 6] performance measures and practice guidelines were modified in 2005 and 2007, respectively, to recommend routine collection in only the sickest patients with CAP.[2, 7] Despite recommendations for a more narrow set of indications, the collection of blood cultures in patients hospitalized with CAP continued to increase.[8]

Distinguishing CAP from other respiratory illnesses may be challenging. Among patients presenting to the ED with an acute respiratory illness, only a minority of patients (10%30%) are diagnosed with pneumonia.[9] Therefore, the harms and costs of inappropriate diagnostic tests for CAP may be further magnified if applied to a larger population of patients who present to the ED with similar clinical signs and symptoms as pneumonia. Using a national sample of ED visits, we examined whether there was a similar increase in the frequency of blood culture collection among patients who were hospitalized with respiratory symptoms due to an illness other than pneumonia.

METHOD

RESULTS

This study included 4854 ED visits, representing approximately 17 million visits by adult patients hospitalized with respiratory symptoms due to a nonpneumonia illness. The most common primary ED provider's diagnoses for these visits included heart failure (15.9%), chronic obstructive pulmonary disease (12.6%), chest pain (11.9%), respiratory insufficiency or failure (8.8%), and asthma (5.5%). The characteristics of these visits are shown in Table 1.

The proportion of blood cultures collected in the ED for patients hospitalized with respiratory symptoms due to a nonpneumonia illness increased from 9.9% (95% confidence interval [CI]: 7.1%‐13.5%) in 2002 to 20.4% (95% CI: 16.1%‐25.6%) in 2010 (P<0.001 for the trend). This observed increase paralleled the increase in the frequency of culture collection in patients hospitalized with CAP (P=0.12 for the difference in temporal trends). The estimated absolute number of visits for respiratory symptoms due a nonpneumonia illness with a blood culture collected increased from 211,000 (95% CI: 126,000296,000) in 2002 to 526,000 (95% CI: 361,000692,000) in 2010, which was similar in magnitude to the estimated number of visits for CAP with a culture collected (Table 2).

DISCUSSION

In this national study of ED visits, we found that the collection of blood cultures in patients hospitalized with respiratory symptoms due to an illness other than pneumonia continued to increase from 2002 to 2010 in a parallel fashion to the trend observed for patients hospitalized with CAP. Our findings suggest that the heightened attention of collecting blood cultures for suspected pneumonia had unintended consequences, which led to an increase in the collection of blood cultures in patients hospitalized with conditions that mimic pneumonia in the ED.

There can be a great deal of diagnostic uncertainty when treating patients in the ED who present with acute respiratory symptoms. Unfortunately, the initial history and physical exam are often insufficient to effectively rule in CAP.[13] Furthermore, the challenge of diagnosing pneumonia is amplified in the subset of patients who present with evolving, atypical, or occult disease. Faced with this diagnostic uncertainty, ED providers may feel pressured to comply with performance measures for CAP, promoting the overuse of inappropriate diagnostic tests and treatments. For instance, efforts to comply with early antibiotic administration in patients with CAP have led to an increase in unnecessary antibiotic use among patients with a diagnosis other than CAP.[14] Due to concerns for these unintended consequences, the core measure for early antibiotic administration was effectively retired in 2012.

Although a smaller percentage of ED visits for respiratory symptoms had a blood culture collected compared to CAP visits, there was a similar absolute number of visits with a blood culture collected during the study period. While a fraction of these patients may present with an infectious etiology aside from pneumonia, the majority of these cases likely represent situations where blood cultures add little diagnostic value at the expense of potentially longer hospital stays and broad spectrum antimicrobial use due to false‐positive results,[5, 15] as well as higher costs incurred by the test itself.[15, 16]

Although recommendations for routine culture collection for all patients hospitalized with CAP have been revised, the JCAHO/CMS core measure (PN‐3b) announced in 2002 mandates that if a culture is collected in the ED, it should be collected prior to antibiotic administration. Due to inherent uncertainty and challenges in making a timely diagnosis of pneumonia, this measure may encourage providers to reflexively order cultures in all patients presenting with respiratory symptoms in whom antibiotic administration is anticipated. The observed increasing trend in culture collection in patients hospitalized with respiratory symptoms due to a nonpneumonia illness should prompt JCAHO and CMS to reevaluate the risks and benefits of this core measure, with consideration of eliminating it altogether to discourage overuse in this population.

Our study had certain limitations. First, the omission of 2005 and 2006 data prohibited an evaluation of whether culture rates slowed down among patients hospitalized with respiratory symptoms due to a nonpneumonia illness after revisions in recommendations for obtaining cultures in patients with CAP. Second, there may have been misclassification of culture collection due to errors in chart abstraction. However, abstraction errors in the NHAMCS typically result in undercoding.[17] Therefore, our findings likely underestimate the magnitude and frequency of culture collection in this population.

In conclusion, collecting blood cultures in the ED for patients hospitalized with respiratory symptoms due to a nonpneumonia illness has increased in a parallel fashion compared to the trend in culture collection in patients hospitalized with CAP from 2002 to 2010. This suggests an important potential unintended consequence of blood culture recommendations for CAP on patients who present with conditions that resemble pneumonia. More attention to the judicious use of blood cultures in these patients to reduce harm and costs is needed.