Immediate surgical outcomes for radical prostatectomy in the University HealthSystem Consortium Clinical Data Base: the impact of hospital case volume, hospital size and geographical region on 48 000 patients

OBJECTIVE: To determine the impact of hospital variables on immediate surgical outcomes for patients treated with radical prostatectomy (RP) in academic centres. PATIENTS AND METHODS: The University HealthSystem Consortium (UHC) Clinical Data Base was queried for data corresponding to patients who had RP at one of 130 academic medical centres nationwide between 2003 and the second quarter of 2007 (48,086). RP case volume (1-99, 100-499 and >500), total discharges (1-49,999, 50,000-99,999 >100,000), and geographical region (five categories) were determined and categorized for each academic centre. Analysis of variance and the Tukey statistic were used to assess the results. Length of stay (LOS), intensive care unit (ICU) rate, complication rate (CR) and in-hospital mortality (IHM) were analysed. RESULTS: Case volume was a significant predictor of LOS, ICU and CR. The mean LOS was 3.77, 2.65 and 2.09 days, respectively, for centres from three tiers of lowest to highest case volumes (P < 0.001). ICU rates for the three tiers were 18.57, 3.61, and 1.30 (P < 0.001); CRs were 15.93, 8.79 and 5.76 (P < 0.001). Tukey analysis showed a 'ceiling' effect for ICU and CRs; there were no differences between the two higher case-volume groups. IHM was not significantly different between groups stratified by case volume. Stratification by total discharges showed differences in ICU rates only (P = 0.003). Stratification by geographical region showed no differences in outcome. CONCLUSIONS: RP case volume was an important variable in predicting three of the four outcome variables. CRs and ICU rates showed a 'ceiling effect' suggesting that an unknown 'critical volume' of cases portends improved surgical outcomes.