Factors for Opioids Use in the Early Treatment Options for the Knee Osteoarthritis Patients

Abstract

Background/Purpose: Current guidelines for osteoarthritis (OA) treatment recommend a range of nonpharmacological and pharmacological interventions to alleviate pain, improve function and quality of life. Most guidelines do not recommend opioids for OA treatment as an early treatment option, but some guidelines suggest using opioids on a restricted basis for short-term use in select patients with refractory symptoms. Although opioids can emerge as a treatment option that may provide effective pain relief with less risk than NSAIDs, they have the potential to cause harm. Until now, the current burden of opioid use for knee OA in Korea is not well understood. We investigated how many prescriptions of opioids for early knee OA treatment are given in Korea, and examined the factors related with opioid use in the early treatment options for knee OA.

Methods: Using the Korean nationwide claims database, all knee OA patients during 2013-2015 were identified by our validated operational definition. Among them, we extracted incident cases to identify opioid use in the early treatment options for knee OA patients. Opioids included tramadol as a weak opioid, and the utilization of opioids was analyzed by dividing strong opioids and weak opioids. A multivariable model was constructed to examine the factors related with opioids use.

Results: Among a total of 2,857,999 incident knee OA patients, 12.2% (n=348,516) were treated with opioids in their first year after diagnosis. However, strong opioid use (not including tramadol) was only 0.07% among the knee OA patients (n=1,972). Opioid users were slightly older (64.2 vs. 64.0 years old, p<0.01) and more likely to be male (44.0% vs. 37.8%, p<0.01) than opioid non users. Most of the opioids (88.6%) were prescribed in community hospitals and clinics. The frequency of opioid prescription was highest in the department of orthopedic surgery (70.1%), followed by internists (9.7%). Elixhauser comorbidity index score was higher in opioid users (4.51±6.36 vs. 4.43±6.23, p<0.01). Related factors with early opioid use were older age (≥70 years old: odds ratio [OR], 1.02; 95% confidence interval [CI], 1.01-1.03, reference 50-59 years old), male (OR 1.29; 95% CI, 1.28-1.30), and medical aid patients (OR 1.13; 95% CI, 1.12-1.15). In terms of comorbidities present, there were peptic ulcer disease (PUD) (OR 1.03; 95% CI, 1.02-1.04), depression (OR 1.05, 95% CI, 1.04-1.06), and musculoskeletal diseases (low back pain: OR 1.12; 95% CI, 1.12-1.13, intervertebral disc: OR 1.11, 95% CI, 1.10-1.13, spinal stenosis: OR 1.27, 95% CI, 1.26-1.29, fibromyalgia: OR 1.14, 95% CI, 1.11-1.17), while diabetes (OR 0.98, 95% CI, 0.97-0.99) and malignancy (OR 0.89, 95% CI, 0.88-0.90) were protective.

Conclusion: In Korea, strong opioid use is not common as a treatment option for early knee OA treatment, but tramadol use is common. Being elderly, male, having comorbidities such as PUD and musculoskeletal diseases, and medical aid patients were more likely to be treated with strong opioids or tramadol.