Clinical comorbidities, treatment patterns, and direct medical costs of patients with osteoarthritis in usual care: A retrospective claims database analysis

Objective: Comorbidities and resource utilization among patients with osteoarthritis (OA) in clinical practice have been infrequently characterized. The purpose of this study was to examine comorbidities, pain-related pharmacotherapy, and direct medical costs of patients with OA in clinical practice. Method: This retrospective cohort analysis used medical and pharmacy claims data from the LifeLink™ Database. OA patients (ICD-9-CM codes 715.XX) were matched (age, gender, and region) with individuals without OA. Comorbidities, pain-related pharmacotherapy, and direct medical costs (pharmacy, outpatient, inpatient, total) were examined for the calendar year 2008. Results: The sample consisted of 112,951 OA patients and 112,951 controls (mean age: 56.9 [SD = 9.5] years; 62% female). Relative to controls, OA patients were significantly more likely (p < 0.0001) to have comorbidities, including musculoskeletal (84.3 vs. 37.1%) and neuropathic pain (22.0 vs. 6.1%) conditions, depression (12.4 vs. 6.4%), anxiety (6.6 vs. 3.5%), and sleep disorders (11.9 vs. 4.2%). OA patients were significantly more likely (p < 0.0001) to receive pain-related medications, including opioids (40.7 vs. 17.1%), NSAIDs (37.1 vs. 11.5%), tramadol (9.8 vs. 1.8%), and adjunctive medications for treating depression, anxiety, and insomnia. Mean [SD] total direct medical costs were more than two times higher among OA patients ($12,905 [$21,884] vs. $5099 [$13,855]; p < 0.001) and median costs were more than three times higher ($6188 vs. $1879; p < 0.0001). Study limitations include potential errors in coding and recording; overestimation of the comorbidity burden; inability to link condition of interest, OA, with prescribed medications; and possible underestimation of the true costs of OA, because indirect costs were not considered and the direct costs were from a third party payer (commercial insurance) perspective. Conclusion: The patient burden of OA was characterized by a high prevalence of comorbidities. The payer burden was also substantial, with significantly greater use of pain-related and adjunctive medications, and higher direct medical costs.