Research Highlights: Larger Hospitals Associated with Lower Mortality for Three Common Conditions

Larger Hospitals Associated with Lower Mortality for Three Common Conditions
By: Caroline Melhado

A recent study published in the New England Journal of Medicine found that patients suffering from acute myocardial infarction, heart failure and pneumonia had lower rates of death after 30 days if they were admitted to a larger hospital. A review of standard Medicare analytic files demonstrated that patients admitted to a larger hospital had a reduction in mortality, however this reduction hit a threshold level, as reduction was insignificant as the hospital volume grew past the threshold.

The study included 734,972 patients of myocardial infarctions from 4,128 hospitals, 1,324,287 for patients for heart failure at 4,679 hospitals, and 1,418,252 patients admitted with pneumonia at 4,673 hospitals. Hospitals not included were those that had fewer then ten patients annually. Researchers found that increasing the annual volume by 100 patients in a hospital was correlated to a 20% reduction in death after 30 days for patients admitted with acute myocardial infarction. Likewise heart failure showed an increase by 100 patients annually would lead to a 10% decrease in 30-day mortality, and a 5% reduction of mortality for patients with pneumonia. However, when the volume of a hospital reached 610 patients, the decrease in 30-day mortality was no longer significant for myocardial infarction. Thresholds for heart failure and pneumonia were 500 and 210, respectively.

Of the hospitals included in the study 25% were teaching hospitals, and 27% had cardiovascular revascularization services. While larger hospitals were more likely to have these characteristics, stratification of each of these components showed that they were not significant confounding variables. Limitations to this study are that only these three conditions were studied, and therefore the widespread application of larger hospitals for many more common medical problems might not follow this trend.

As policy makers grapple with ways to improve the healthcare system, researchers are studying profound ways to improve the outcomes of patients of common medical problems. While both negative and positive outcomes of these three conditions at large and small hospitals existed, the overall reduction in mortality at larger hospitals might shape future public health policy to favor larger medical institutions.

NEJM Volume 362:1110-1118