Relationship between annual volume of patients treated by admitting physician and mortality after acute myocardial infarction

Context — Acute myocardial infarction (AMI) is a common condition that is treated by physicians with varying levels of clinical experience, but whether the level of experience affects outcome remains uncertain.

Objective — To evaluate the relationship between the average annual volume of cases treated by admitting physicians and mortality after AMI.

Design, Setting, and Patients — Retrospective cohort study using linked administrative databases containing patient admission information for 98 194 patients treated by 5374 physicians between April 1, 1992, and March 31, 1998, in Ontario, Canada.

Main Outcome Measures Mortality risk rates for 30 days and 1 year post-AMI, adjusted by physician volume and patient, physician, and hospital characteristics.

Results — The 30-day mortality rate was 13.5% and the 1-year mortality rate was 21.8%. A strong inverse relationship between the average annual volume of AMI cases treated by the admitting physician and mortality after an AMI was observed. The 30-day risk-adjusted mortality rate was 15.3% for physicians who treated 5 or fewer AMI cases per year (lowest quartile) compared with 11.8% for physicians who treated more than 24 AMI cases annually (highest quartile; P<.001). The 1-year risk-adjusted mortality rate was 24.2% for physicians who treated 5 or fewer AMI cases per year (lowest quartile) compared with 19.6% for physicians who treated more than 24 AMI cases annually (highest quartile; P<.001).

Conclusion — Patients with AMI who are treated by high-volume admitting physicians are more likely to survive at 30 days and 1 year.