Hospital Staffing and Inpatient Mortality

Staff-to-patient ratios are a current policy concern in hospitals nationwide. Legislators in California and New York have imposed staffing requirements on hospitals that are estimated to cost hundreds of millions of dollars per year. These reforms were motivated by the presumption of a causal link between lower hospital staffing levels and adverse patient outcomes. However, the cited empirical evidence is based almost entirely on acrosshospital comparisons, which is problematic if the nonrandom selection of patients into hospitals leads to unobservable differences across hospitals in patient characteristics and illness severity. By contrast, this paper uses the significant reduction in the number of doctors on staff on the weekend to estimate the effects of staffing on mortality rates. Within-hospital comparisons in outcome differences between weekday and weekend admissions have two advantages over previous research. First, the observable differences in patient characteristics are much smaller within hospitals than across hospitals. More importantly, it is possible to construct an index that corrects for biases due to unobservable selection into staffing regimes that is based on the excess share of admissions that occur on weekdays. Consistent with previous research, there is a robust association between excess mortality and weekend admission even after regression-adjustment. However, correcting for nonrandom selection in favor of weekday admissions leads to a finding of no excess mortality among patients admitted on the weekend. This suggests that despite a significant reduction in the number of doctors and services provided on the weekend, hospitals are effective in triaging patients with less severe conditions.