The effect of hospital-type and operating volume on the survival of hip replacements - A review of 39,505 primary total hip replacements reported to the Norwegian Arthroplasty Register, 1988-1996

We investigated associations between the survival of total hip replacements (THRs), type of hospital and annual number of THRs per hospital. The study was based on 39,505 primary THRs reported to the Norwegian Arthroplasty Re gister from 45 local (n 20,756), 15 central (n 12,455) and 10 university ho spitals (n 6,294) during 1988-1996. The annual number of THRs was highest a t central and university hospitals, both of which are training hospitals. U niversity hospitals were further characterized by the lowest mean annual nu mber of THRs performed per surgeon. For cemented THRs, with adjustment for gender, age, diagnosis, surgical pro cedure, and annual hospital volume, the revision rates at central and unive rsity hospitals were 0.8 (95% confidence interval: 0.67-0.95) and 1.2 (CI: 1.02-1.47) times that of local hospitals, respectively A high annual number of cemented THRs per hospital was not associated with lower revision rates . In uncemented THRs, survival results were similar in central and local hosp itals, whereas the adjusted revision rate at university hospitals was 1.6(C I: 1.13-2.19) times that of local hospitals. The adjusted 6.5 year revision probability was 12% in hospitals performing less than or equal to 10 uncem ented THRs per year (n 606), 8% in hospitals performing from 18-28 operatio ns (n 1,378) and 5% in hospitals performing > 84 operations (n 526).