Total Hip Replacement: Practice Makes Perfect – Procedure Volume Predicts Operative Time, Rehabilitation, Inpatient Cost, and LOS

Early rehabilitation and complication prevention in Total Hip Replacement (THA) are facilitated by prompt post-surgical healing, optimum biomechanics, and minimal tissue damage, all impacted by surgical skill. Skilled surgeons may have lower average operating times. We examined whether practice makes perfect, by testing whether: a) Increasing physician THA volume (but not hospital volume) is associated with reduced operative time; b) Increasing physician and hospital volume are associated with better outcomes (lower readmission rates and mortality, early initiation and sustained rehabilitation,) and lower costs (inpatient cost and length of stay, LOS); c) Lower operative time mediates physician volume-outcome and volume-cost relationship: operative time will significantly predict mortality, rehabilitation, inpatient cost and LOS. We analyzed all 13,681 (population-based) inpatient claims from Taiwan's National Health Insurance, excluding secondary and traumatic fractures using proxy variables for operative time, anesthesia costs (proportional to anesthetist time), and for early rehabilitation (physiotherapy fraction of inpatient cost). We use hierarchical linear and logistic regression modeling, adjusting for patient and physician demographics, hospital characteristics, and co-morbidities, introducing random effect for hospital in the physician volume analyses, and for physician in the hospital volume analyses. To test physician and hospital volume versus operative time, we controlled for liver and kidney dysfunction, hypertension and diabetes, which impact intra-surgical decisions, and for other regressions, the Charlson-Deyo Comorbidity Index. We sorted physicians/hospitals in ascending order of volume, to establish volume cutoffs such that patients fell into one of three volume groups of about equal cell sizes. Physician groups: Low °Ü24 cases, Medium 25-72, High °Ý73. Hospital groups: Low °Ü105, Medium 106-303, High °Ý304. For physicians, increasing volume predicts lower anesthesia cost, LOS and inpatient costs, and higher physiotherapy cost fraction. For hospitals, results are similar except that volume does not predict anesthesia cost. Association of anesthesia cost with in-hospital mortality, readmission, inpatient cost and LOS, and physiotherapy fraction will be presented. We conclude that surgeon's performance quality improves with increasing volume, because volume predicts lower operative time, lower adjusted inpatient costs, and higher physiotherapy cost fraction. The hospital volume findings may reflect the role of ancillary care organization in quality and cost outcomes. Practice indeed makes perfect, and operative time is a subtle proxy for surgical skill. Skilled surgeon backup should be available during all surgeries by less experienced physicians to save lives, reduce costs, and facilitate speedy patient healing and functional rehabilitation.