Heart Failure in Primary Care Measuring the Quality of Care

Discussion

Three important observations come from our study. Heart failure patients in primary care are heterogeneous, with half of the patients having a normal LVEF. The demographic variables in this study and others¹⁷ suggest that primary care heart failure patients are older and have more comorbidities than participants in randomized clinical trials of ACE inhibitors.¹⁸ These findings make assessments of quality of care difficult at best and impossible with certain methodologies. Primary care physicians’ use of ACE inhibitors in systolic heart failure patients is higher here than reported in other published studies Table 4. Finally, the accurate assessment of quality for chronic disease management in primary care is dependent on the use of appropriate methods and measures sensitive to the longitudinal processes of care. Study time frames influence the accuracy of quality assessments.

Previous studies have suggested that the diagnosis of heart failure in primary care is substandard because of overdiagnosis.^6,19 Yet, research is hampered by a lack of specificity in classifying heart failure. ICD-9-CM codes do not currently account for the different classes of heart failure. Although misdiagnosis occurs in practice, our data suggest that the syndrome of heart failure is heterogeneous, with systolic and diastolic heart failure being equally prevalent. This finding is perhaps not surprising given the age of our cohort, and is consistent with other studies suggesting a high incidence of heart failure with normal LVEF.^17,20 Determining the veracity of the diagnosis is vital for measuring quality.

Current views of heart failure may be no more accurate than musings on presbycardia were 50 years ago.²¹ Since primary care heart failure patients are older and have more comorbidities than participants in randomized clinical trials, important questions are raised about the generalizability and effectiveness of interventions on the basis of our best scientific evidence.

In Table 4 we summarize other studies that have assessed physician performance with heart failure patients. The performance standard for LVEF measurement in our study is similar to that found in a recent outpatient study²² that used the same ICD-9-CM selection criteria. Three other outpatient studies^19,23,24 were completed in the United Kingdom, where access to LVEF tests may be more limited than in the United States. Our findings reiterate the importance of an early measure of LVEF to classify heart failure, because a physician’s use of ACE inhibitors was strongly associated with documentation of a low LVEF. Among the 18% of patients in the initial study sample who had no documented measure of LVEF, the performance rate for ACE inhibitor use (78%) was significantly lower than the threshold rate recommended for systolic heart failure patients. It is unlikely that clinical characteristics could distinguish between heart failure classes.³¹

Misclassification of patients with heart failure is an important concern, both clinically and within administrative databases, and is complicated by comorbidities and uncertainties about the disease process over time. Many studies that suggest low physician compliance with ACE inhibitor prescription did not classify heart failure patients according to LVEF status.^3,4,5,24 In our study and in most others that classified heart failure by LVEF, however, there were substantially higher rates of ACE inhibitor use for patients with systolic heart failure.^{25-28, 22} Also, the studies reporting the lowest compliance rates had less specific sample selection criteria than our study, using more ICD-9-CM codes.^4,5,29 Two studies suggesting low compliance were based on physician self-report.^3,5 Although the National Ambulatory Medical Care Survey provides insightful snapshots of physician practices, it may underestimate pharmaceutical use over time for chronic diseases; ACE inhibitors were not linked to measures of LVEF for heart failure.⁵ The questionnaire used by Edep³ and others to assess physician performance presented standard descriptions of heart failure patients with low LVEF but then asked physicians to respond on the basis of their population of heart failure patients, not the specific patient presented. According to our data, those primary care physicians may have accurately reflected their use of ACE inhibitors with their population of heart failure patients, since a large proportion may have had normal LVEFs.

Compared with studies that did classify by LVEF, the compliance of New York family physicians with the AHCPR clinical guideline recommendation for ACE inhibitor use is higher than that found in an academic setting²² and in 2 studies of Medicare patients hospitalized for heart failure.^27,29 Other studies^25,26,30 have examined ACE inhibitor use for heart failure patients by internists and cardiologists and also found lower rates of use in the hospital setting. Our study could reflect actual change in clinician behavior since the dissemination of the guideline. However, it more likely reflects the degree to which our study controlled for the classification of heart failure according to LVEF and the time frame for our observation.³¹ The overall compliance rate for use of ACE inhibitors was 74% among patients with heart failure, verified through chart review. Yet, among patients with a confirmed LVEF · 40% and corrected for patients with contraindications, the performance rate was 91%.