Impact of Knee Osteoarthritis on Health Care Resource Utilization in a US Population-Based National Sample

Knee osteoarthritis (OA) affects approximately 12% of Americans aged 60 and above,1 and accounts for substantial disability among the elderly.2–5 Knee OA is often accompanied by comorbid conditions, functional limitation, and obesity.6–10 Health care utilization is extensive among knee OA patients, including hospital inpatient and ambulatory services.11,12 Prior studies have shown that the cost for health services among persons with OA exceeded those without OA by 1.5- to 2.6-fold.13–17 This burden will increase as the population ages. Previous research has examined health care utilization and/or cost among OA or arthritis patients in European populations,18–21 community-based cohorts,14,15,22 a state-wide pharmaceutical assistance program,22 HMO populations,12,13,16,23,24 and US Department of Veterans Affairs (VA) populations.25 Only a few of these studies compared OA patients with non-OA patients and controlled for potential confounding factors, such as comorbidity, to determine cost and/or utilization attributable to OA,13,26 and none of these studies has focused solely on knee OA. The present study aims to compare health care utilization in persons with knee OA to those without OA in a US population-based sample. The study uses a national database linking Medicare claims with detailed survey data and focuses on knee OA, the most debilitating form of OA.2 We hypothesize that knee OA contributes significantly to health care utilization, independent of comorbidities, and functional limitation.