Population-Based Study of Relationships Between Hospital Volume of Prostatectomies, Patient Outcomes, and Length of Hospital Stay

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Abstract
BACKGROUND: Despite the large number of prostatectomies performed annually, few data exist regarding relationships between the volume of prostatectomies handled by a hospital, the length of a patient's stay in the hospital, and patient outcomes. We examined the effect of hospital prostatectomy volume and changes in the hospital volume on patient outcomes and the length of a patient's stay. METHODS: We collected data on 101 604 prostatectomies from Medicare claims filed from 1991 through 1994. By use of logistic regression and analysis of variance, we examined relationships between hospital load of prostatectomies, length of a patient's hospital stay, surgical complications, readmission rate, and mortality rate in a 30-day period following surgery. Statistical tests were two-sided. RESULTS and CONCLUSIONS: Cross-sectional analyses revealed that, compared with high-volume hospitals, low-volume, medium-low-volume, and medium-high-volume hospitals had higher relative risks of readmission by 30% (95% confidence interval [CI] = 21%-39%), 16% (95% CI = 7%-25%), and 8% (95% CI = -1% to 17%), respectively; higher relative risks of serious complications by 43% (95% CI = 37%-48%), 25% (95% CI = 19%-31%), and 9% (95% CI = 3%-15%), respectively; and higher relative risks of mortality by 51% (95% CI = 25%-77%), 43% (95% CI = 17%-69%), and 42% (95% CI = 16%-68%), respectively. The mean length of a patient's stay in a low-volume hospital was 9% longer than that in a high-volume hospital (8.51 days [95% CI = 8.47-8.56] versus 7.81 days [95% CI = 7.77-7.85]; P for trend across all volume categories = .0001). Within-hospital longitudinal analyses revealed that hospitals with a relative increase in prostatectomy volume had a 57% greater reduction in the length of a patient's stay compared with those with a relative decrease in volume ( P = .005). Changes in prostatectomy volume did not affect the frequency of complications, mortality, and readmission. These findings suggest that an increase in a given hospital's prostatectomy volume may facilitate a decrease in the length of a patient's stay without an adverse impact on patient outcomes.