Is gabapentin used as an alternative for opioids? Characterizing gabapentin initiation in Medicare beneficiaries

Background: Off-label use of gabapentin in older adults has surged, and this rise is hypothesized to be driven by clinicians seeking safer opioid alternatives. Thus, understanding the characteristics of gabapentin initiators with and without opioid history is crucial to ensure safe usage.

Objectives: To describe demographic and medical characteristics of fee-for-service Medicare beneficiaries initiating gabapentin within strata defined by history of opioid use.

Methods: We conducted a retrospective cohort study using a 5% random Medicare sample (2012-2016). Beneficiaries 65 years and older were eligible if they were enrolled due to age in Medicare Parts A, B, and D. Gabapentin initiation was determined from pharmacy claims based on a prescription following continuous enrollment for at least 180 days (washout period). Gabapentin initiators were categorized by opioid analgesics history based on opioid prescriptions during the washout period. We used enrollment and chronic condition files along with pharmacy and medical claims and conducted descriptive statistics to evaluate the distribution of demographic characteristics, chronic conditions, and medical history to characterize the initial gabapentin prescription.

Results: Among eligible Medicare beneficiaries (N=898,663), 8.2% (N=73,571) initiated gabapentin (mean (SD) age = 76.1 (7.3); female = 63.1%) with 33.5 (19.2) mean (SD) days of supply. Among gabapentin initiators, 0.3% had a diagnosis of epilepsy and 3.2% had a diagnosis of neuropathic pain, the two labelled indications for gabapentin. Almost one-half (47.2%) of gabapentin initiators had an opioid prescription during the washout period and of those, 56.1% used opioid with gabapentin at index date compared to 8.6% of gabapentin initiators without opioid history. The prevalence of pain was higher in gabapentin initiators with opioid history vs. without (acute pain: 6.7% vs. 3.2%; back/neck pain: 5.5% vs. 1.5%; chronic pain: 19.3% vs. 8.1%; neuropathic pain: 4.3% vs. 2.3%). Additionally, most chronic conditions were more prevalent in gabapentin initiators with opioid history: depression (with vs. without opioid history: 33.3% vs. 25.7%), hip fracture (2.6% vs. 1.7%), osteoporosis (18.6% vs. 15.2%), rheumatoid arthritis (72.6% vs. 56.6%), hypertension (84.8% vs. 80.5%), acute myocardial infarction (2.4% vs. 1.9%), ischemic heart disease (45.2% vs. 40.4%), and any cancer (29.9% vs. 28.1%).

Conclusions: A high proportion of gabapentin initiators concurrently used gabapentin with opioids, with higher burden of pain and comorbidities among those with opioid history. Future studies are needed to examine the risk and benefit of initiating gabapentin within different prescription patterns.