Association between muscle atrophy/weakness and health care costs and utilization among patients receiving total knee replacement surgery: a retrospective cohort study

PURPOSE The aim of the study reported here was to examine health care resource utilization, costs, and risk of rehospitalization for total knee replacement (TKR) patients with and without muscle atrophy/weakness (MAW). PATIENTS AND METHODS Individuals aged 50-64 years with commercial insurance or 65+ years with Medicare Supplemental Insurance (Medicare) who had a hospitalization for TKR between January 1, 2006 and September 30, 2009 were identified from a large US claims database. First hospitalization for TKR was defined as the index stay. All patients were classified into three cohorts according to when MAW was diagnosed relative to TKR: pre-MAW, post-MAW, and no MAW. The association between MAW and health care costs over the 12-month post-index period and the probability of rehospitalization were assessed via multivariate regressions. RESULTS The study sample included 53,696 Medicare and 46,058 commercial insurance TKR patients. Controlling for cross-cohort differences, both the pre- and post-MAW cohorts had significantly higher total health care costs (Medicare US$4,201 and US$9,404 higher, commercial insurance US$2,737 and US$6,640 higher, respectively) than the no MAW cohort (all P < 0.05). The post-MAW cohort in both populations was also more likely to have any all-cause or replacement-related rehospitalization compared with the no MAW cohort. CONCLUSION Among US patients undergoing TKR, those with MAW had higher health care utilization and costs than patients without MAW.