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Opioid use among Medicare beneficiaries with knee osteoarthritis: prevalence and correlates of chronic use.

OBJECTIVE
To determine the prevalence of chronic and occasional opioid use and identify risk factors of opioid use among persons with knee osteoarthritis.


METHODS
We used the Medicare Current Beneficiary Survey (MCBS) to select a knee OA cohort. We obtained data on demographics, marital status, comorbidities, insurance and prescription medication coverage from survey data and linked Medicare claims. We included all prescribed medication records classified as opioid under the First Databank therapeutic antiarthritics or analgesics categories. We stratified knee OA subjects into three opioid use groups: 1) non-users (0 prescriptions/year), 2) occasional users (1-5 prescriptions/year) and 3) chronic users (6+ prescriptions/year). We built multivariable logistic regression models using a Generalized Estimating Equation (GEE) to determine correlates of chronic opioid use.


RESULTS
Among 3,549 Medicare beneficiaries with knee OA and a mean age of 78 (SD 7) years, 68% were females, 9% were chronic users and 21% used opioids occasionally. Multivariable analysis showed that non-Hispanic ethnicity (OR 4.8, 95% CI [2.2, 10.2]), divorced status (vs. married) (OR 2.3, 95% CI [1.5, 3.5]), Medicaid eligibility (OR 1.9, 95% CI [1.3, 2.7]), depression (OR 1.9, 95% CI [1.5, 2.5]), COPD (OR 1.9, 95% CI [1.4, 2.5]) and inability to walk without assistive devices (vs. no difficulty walking) (OR 2.4, 95% CI [1.5, 3.7]) were independently associated with chronic opioid use.


CONCLUSION
9% of persons with knee OA use opioids chronically. Efforts to find non-opioid regimens for treating knee OA pain should be tailored to patients at high risk for chronic use.