Impact of Hospital Case Volume on the Complication Rate in Hip Arthroplasty: An Analysis of Nationwide AOK Data.

Due to demographic changes and the associated expected increases in the number of primary hip arthroplasty and revision surgeries, it is important to identify factors that can reduce complications and revisions. One such factor is the hospital volume. Studies have shown that hospitals with higher case numbers have lower morbidity and complication rates. Most studies are based on registry data, which is often incomplete and does not include patient-specific factors.In this study, nationwide pseudonymised inpatient data and insurance records from the Allgemeine Ortskrankenkasse (AOK) from 2017 to 2019 in patients with primary hip arthroplasty were analysed. To examine the impact of hospital case volume on outcomes, five volume categories were created (I: 1-49, II: 50-99, III: 100-199, IV: 200-399, V: ≥ 400 operations per year). The endpoints considered were 90-day mortality, 1-year revision surgeries, surgical complications (90 days and 365 days), periprosthetic femur fractures (90 days), and serious general complications during the hospital stay. The effect of hospital volume on outcomes was analysed using multiple logistic regression, considering patient-specific factors.The analysis of 137,494 cases from 993 clinics shows a statistically significant relationship between the case number group and the frequency of revision surgeries, surgical complications, periprosthetic femur fractures, and general complications. Clinics with fewer than 50 cases per year showed an increased risk of 65% to 88% for these endpoints compared to the group with the highest case numbers. For the endpoint mortality, a dichotomous consideration of the volume categories also shows a significant influence by the hospital volume.The study shows that higher case volume in primary hip arthroplasty is associated with lower complication rates, even when considering patient-specific factors. These findings underline the importance of case numbers as a factor for improving the quality of care in hip arthroplasty.