Should Hospitals Keep Their Patients Longer? The Role of Inpatient Care in Reducing Postdischarge Mortality

The Centers for Medicare & Medicaid Services (CMS) and the National Quality Forum have endorsed the 30-day mortality rate as an important indicator of hospital quality. Concerns have been raised, however, as to whether postdischarge mortality rates are reasonable measures of hospital quality as they consider the frequency of an event that occurs after a patient is discharged and is no longer under the watch and care of hospital staff. Estimating the causal effect of length of stay (LOS) on postdischarge mortality from retrospective data introduces a number of econometric challenges. We describe three potential sources of (endogeneity and censoring) biases and propose an approach that provides conservative estimates of the true treatment effect. Using a large data set comprising all hospital encounters of every Medicare fee-for-service patient with acute myocardial infarction from 2000 to 2011, we find evidence that an increase in LOS is associated with a decrease in 30-day mortality rates. An additional day in the hospital could decrease 30-day mortality rates by over 6%. Moreover, we find that, from a social planner's perspective, the gains achieved in reducing mortality rates likely exceed the cost of keeping the patients in the hospital for an additional day.