Hospital Volume Does Not Influence the Safety of Percutaneous Nephrolithotomy in England: A Population-Based Cohort Study.

PURPOSE: This study aims to investigate the relationship between hospital case volume and safety-related outcomes after percutaneous nephrolithotomy (PCNL) within the English National Health Service (NHS). PATIENTS AND METHODS: The study used the Hospital Episode Statistics (HES) database, a routine administrative database, recording information on operations, comorbidity, and outcomes for all NHS hospital admissions in England. Records for all patients undergoing an initial PCNL between April 1, 2006 and March 31, 2012 were extracted. NHS trusts were divided into low-, medium-, and high-volume groups, according to the average annual number of PCNLs performed. We used multiple regression analyses to examine the associations between hospital volume and outcomes incorporating risk adjustment for sex, age, comorbidity, and hospital teaching status. Postoperative outcomes included: Emergency readmission, infection, and hemorrhage. Mean length of stay was also measured. RESULTS: There were 7661 index elective PCNL procedures performed in 163 hospital trusts, between April 2006 and March 2012. There were 2459 patients who underwent PCNL in the 116 units performing fewer than 10 PCNL procedures per year; 2643 patients in the 37 units performing 10 to 19 procedures per year; and 2459 patients in the 9 hospitals performing more than 20 procedures per year. For low-, medium-, and high-volume trusts, there was little variation in the rates of emergency readmission (L 9.7%, M 9.3%, H 8.4%), infection (3.0%, 4.2%, 3.8%), or hemorrhage (1.3%, 1.5%, 1.5%), and there was no statistical evidence that volume was associated with adjusted outcomes. Mean length of stay was slightly shorter in the medium- (5.0 days) and high-volume (5.0) groups compared with the low-volume group (5.3). The effect remained statistically significant after adjusted for confounding. CONCLUSION: Hospital volume was not associated with emergency readmission, infection, or hemorrhage. Length of stay appears to be shorter in higher volume units.