Patients hospitalized for acute myocardial infarction (AMI) and heart failure (HF) in regions with a low density of cardiologists experienced modestly higher 30-day and 1-year mortality risk, unlike patients with pneumonia, according to a new study published in Circulation: Cardiovascular Quality and Outcomes.

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The study, which used Medicare administrative claims data from 2010, examined 171,126 admissions for AMI and 352,853 admissions for HF, compared against 343,053 admissions for pneumonia. Study investigators tested associations between density of cardiologists and 30-day and 1-year mortality for each condition and found that patients hospitalized for AMI and HF in regions with a lower density of cardiologists had modestly higher 30-day and 1-year mortality risk compared with patients hospitalized in regions with higher density. There were no relationships between density of cardiologists and mortality among patients hospitalized with pneumonia.

According to the authors, the study findings indicate a relationship between regional density of cardiologists and mortality for AMI and HF, which is concentrated in the early period after these acute events. "If all regions had the same mortality rates as those in the highest quintile of density of cardiologists, there would have been ≈1200 (95% CI, 200–2100) fewer deaths within 30 days of AMI hospitalization and ≈3200 (95% CI, 1700–4500) fewer deaths within 30 days of HF hospitalization," they note.

The authors point out a number of possible explanations for the findings, including that patients hospitalized in regions with a high density of cardiologists may be more likely to be treated by a cardiologists. In addition, competition among cardiologists seeking to sustain their practice(s) in high-density regions may also result in higher quality care. Finally, the average patient admitted to a hospital in regions with a high-density of cardiologists may be less ill. Hospitals in lower-density regions may have higher admission thresholds due to a more limited workforce.

"Deeper understanding of the causes of this observed difference in mortality may potentially reveal a target for interventions to improve outcomes," the authors suggest. For example, lower-density regions may need to look for new approaches to achieving results that are similar to high-density regions.

"Our study highlights that patients may experience a different risk of death based on the density of cardiologists in the region where they are hospitalized," said Vivek T. Kulkarni, AB, of the Yale University School of Medicine, New Haven, CT, and lead author of the study. "As we strive toward a more equitable health care system, we will need to devote greater attention and scrutiny towards understanding these differences. Importantly, our study does not evaluate whether training more cardiologists might improve mortality. Nevertheless, our findings suggest that further efforts should focus on identifying targeted methods to improve mortality in regions with a low density of cardiologists."

Keywords: Myocardial Infarction, Pneumonia, Heart Failure, Medicare, Hospitalization, United States

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