Background/Purpose: Osteoarthritis (OA) of the knee is prevalent among Medicare beneficiaries. Effective pain control is critical for managing this chronic disease. In the last decade, opioids became widely available for persons with knee OA. We sought to identify knee OA patients that use opioids chronically and occasionally, and determine factors associated with greater risk of occasional and chronic opioid use among knee OA patients ≥ 65years of age.

Methods: We used the Medicare Beneficiary Survey (MCBS) of a nationally representative sample of Medicare beneficiaries administered in 2015. MCBS survey data are linked to Medicare claims. We selected a knee OA cohort from community-dwelling MCBS respondents age ≥ 65 who had at least one outpatient visit in Medicare Parts A or B with an ICD-10-CM code of a) M17.9 or b) M25.569 (Pain in unspecified knee) plus M15.x or M19.90. We obtained data on demographics, smoking, marital status, comorbidities and prescribed medications from survey data and claims. We included all prescribed medication records classified as opioids under the First Databank therapeutic analgesics category. We stratified knee OA subjects into three opioid use groups: 1) none, 2) occasional (1-5 prescriptions/year), 3) chronic (6+ prescriptions/year). We built several multivariable logistic regression models to determine independent correlates of any opioid use vs non-use; chronic vs. non-use and chronic vs. occasional use.

Results: We identified a cohort of 620 persons with knee OA. Mean age was 78.5 (SD 7.3), 65% were female. 31% of the cohort had at least one opioid prescription during 2015. 10% of the overall cohort were identified as chronic opioid users, and 21% of the overall cohort as occasional users. Multivariable analyses that compared any opioid use to no use identified several patient features associated with greater risk of opioid use: ≥ 1 fall in the prior year (OR 1.96, 95% CI 1.16-3.30; ≥ 2 comorbidities (OR 2.62, 95% CI: 1.30, 5.29) and use of NSAIDS (OR 3.74, 95% CI: 2.09-6.71). Married beneficiaries had 0.50 odds of using opioids compared to those who were not married (95% 0.30-0.84). When we compared chronic opioid users to no users, features associated with chronic use included low household income (< 30K/annually; OR 6.13, 95% CI: 2.39-15.7; ≥ 2 comorbidities (OR 3.27, 95% CI: 1.25-8.55) and NSAID use (OR 2.77, 95% CI: 1.14-6.71). Comparing chronic users with occasional opioid users, features associated with chronic use included low income (OR 6.15, 95% CI: 2.04-18.44) and current smoking (OR 5.83, 95%CI: 1.15-29.45).

Conclusion: Over 30% of Medicare beneficiaries with knee OA use opioids and 10% use them chronically. Low income, NSAID use and higher burden of comorbidities are associated with greater risk of opioid use, while marriage was associated with lower risk of use. The causal relationship between prior falls, low income and marital status and risk of current opioid use requires further study. Efforts to find non-opioid regimens for knee OA would be especially useful for patients with risk factors identified in this study.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/opioids-use-among-medicare-beneficiaries-with-knee-osteoarthritis-prevalence-and-correlates-of-chronic-use/