Evaluating In-Hospital Safety and Perioperative Costs of Total Hip Arthroplasty in Super-Elderly Patients: A Nationwide Propensity Score–Matched Analysis in Japan

<b>Background:</b> This study aimed to evaluate short-term outcomes, including in-hospital complications, mortality, and medical costs, after total hip arthroplasty (THA) in super-elderly patients aged ≥85 years compared with elderly patients aged 70-84 years, using a nationwide database in Japan. <b>Materials and Methods:</b> We conducted a retrospective cohort study using the Japanese Diagnosis Procedure Combination (DPC) database from 2011 to 2023. Patients undergoing unilateral THA were divided into super-elderly and elderly groups. Propensity score matching (1:1) was performed based on demographics and comorbidities, including Charlson Comorbidity Index (CCI). Primary outcomes included in-hospital complications and mortality; secondary outcomes included hospital length of stay, Barthel Index, and medical costs calculated on a fee-for-service basis for the perioperative period (surgery day through postoperative day 7). <b>Results:</b> A total of 11,997 matched pairs were analyzed. The super-elderly group had significantly higher rates of cerebrovascular events (0.6% vs. 0.3%; OR: 2.125; 95% CI: 1.403-3.219) and in-hospital mortality (0.2% vs. 0.0%; OR: 5.565; 95% CI: 2.106-14.71), though absolute risk differences were small (0.0029 and 0.0017, respectively). Hospital stay was longer in the super-elderly group (32.6 ± 21.3 vs. 29.5 ± 19.5 days). No significant difference in perioperative medical costs was observed between groups. <b>Conclusions:</b> Although super-elderly patients demonstrated slightly higher in-hospital risks of cerebrovascular events and mortality, the absolute risk differences were minimal. These findings suggest that elective THA can be safely performed during hospitalization in this population, although further research is needed to evaluate post-discharge outcomes.