OBJECTIVES : Osteoarthritis is the most common type of joint disease and with its high prevalence it imposes a substantial economic burden to the US payers. This study aimed to identify the main drivers of high costs among privately insured osteoarthritis patients.

METHODS : Patients diagnosed with osteoarthritis from January through December 2014 were identified using the IBM Truven Health Analytics MarketScan® Research Databases. The eligible patients were older than 18 years with a continuous 12-month insurance coverage before and after the initial osteoarthritis diagnosis (index date), with no osteoarthritis diagnosis 12 months prior to index date. We compared demographic and clinical characteristics between high-cost (top 25 percentile) and low-cost patients (the remaining study population). The main drivers of costs in the high-cost patients (HCP) were assessed using multiple logistic regression.

RESULTS : A total of 55,466 osteoarthritis patients aged 54 years (standard deviation [SD]: 7.47), consisting of 58.1% of females were identified. A total of 13,900 patients with the highest costs accounted for 63.3% of expenses of the total study population. The HCP cohort had higher Charlson comorbidity score (mean [SD]: 0.6 [0.75] vs. 0.8 [1.27]) and was more commonly diagnosed with mental disorders (43.6% vs. 31.2%, p<0.01) compared to low-cost patients. Factors associated with being osteoarthritis HCP included hip and/or knee arthroplasty (odds ratio [OR], 8.6; 95% confidence interval [CI], 8.1-9.0), monoclonal antibody therapy (OR, 3.5; 95% CI, 2.7-4.4), at least one emergency department (ED) admission (OR, 2.2; 95% CI, 2.0-2.3), rheumatism (OR, 1.5; 95% CI, 1.4-1.6) and obesity (OR, 1.5; 95% CI, 1.5-1.6).

CONCLUSIONS : High-cost privately insured osteoarthritis patients are associated with increased risk of hip/knee arthroplasty, monoclonal antibody therapy, ED admission, rheumatism and obesity, which are identified as key cost predictors. Cost reduction strategies in high-cost osteoarthritis population should be tailored to these cost drivers.