Patient Care

High-Volume Hospitals Have Higher Readmission Rates


Clinical question: Is there an association between hospital volume and hospital readmission rates?

Background: There is an established association between high patient volume and reduced complications or mortality after surgical procedures; however, readmission represents a different type of quality metric than mortality or complications. Studies on the association between hospital patient volume and readmission rates have been controversial.

Study design: Retrospective, cross-sectional study.

Setting: Acute care hospitals.

Synopsis: The study included 6,916,644 admissions to 4,651 hospitals, where patients were assigned to one of five cohorts: medicine, surgery/gynecology, cardiorespiratory, cardiovascular, and neurology. The hospital with the highest volume group had a hospital-wide mean standardized readmission rate of 15.9%, while the hospital with the lowest volume group had a readmission rate of 14.7%. This was a 1.2 percentage point absolute difference between the two hospitals (95% confidence interval 0.9 to 1.5). This trend continued when specialty cohorts were examined, with the exception of the procedure-heavy cardiovascular cohort.

Results showed a trend toward decreased readmission rates in lower-volume hospitals; however, it is unclear why this trend exists. Possible reasons include different patient populations and different practitioner-to-patient ratios in low-volume hospitals.

Limitations of this study are the inclusion of only patients 65 years and older and the fact that all admissions per patient were included, which may bias the results against hospitals with many frequently admitted patients.

Bottom line: Hospitals with high patient volumes are associated with higher readmission rates, except in procedure-heavy patient groups.

Citation: Horwitz LI, Lin Z, Herrin J, et al.Association of hospital volume with readmission rates: a retrospective cross-sectional study. BMJ. 2015;350:h447.

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