Yale study questions accuracy of relying on patient death rates to compare hospital quality

Hospitals, health insurers and patients often rely on patient death rates in hospitals to compare hospital quality. Now a new study by researchers at Yale School of Medicine questions the accuracy of that widely used approach and supports measuring patient deaths over a period of 30 days from admission even after they have left the hospital.

Published in the Jan. 3 issue of Annals of Internal Medicine, the study has wide implications as quality measures take on more importance in the healthcare system, notes Elizabeth Drye, M.D., a research scientist at Yale School of Medicine's Center for Outcomes Research and Evaluation, who led the research. The study compared two widely used approaches to assessing hospital quality. One approach uses mortality rates of patients who die during their initial hospitalization, and the other uses rates of patients who die within 30 days, whether or not they have been discharged.

Drye and colleagues focused on mortality rates for patients with heart attack, heart failure, and pneumonia. For these conditions, one-third to one-half of deaths within 30 days occur after the patient leaves the hospital, but this proportion often varies by hospital.

"We were concerned that only counting deaths during the initial hospitalization can be misleading," said Drye. "Because some hospitals keep their patients for less time than others due to patient transfers to other facilities or because they send patients home more quickly."

Drye and her colleagues found that quality at many U.S. hospitals looked quite different using the two different accounting methods. The team also found that measures looking only at deaths in the hospital favor hospitals that keep their patients for a shorter length of time.

"To assess current and future patient management strategies," said Drye. "We should assess all patients for a standard time period, such as 30 days."

Drye said the findings have implications for any study that compares hospitals using patient outcomes to judge quality. "We hope the study will inform choices about how we measure quality so that we will be using the best tools for building a higher-quality system," she said.