Predictors of Gabapentin Overuse With or Without Concomitant Opioids in a Commercially Insured U.S. Population.

OBJECTIVE: Research suggests the medical consequences of gabapentin overuse depend on whether gabapentin is abused alone or with opioids to potentiate an opioid "high." The objective of this study was to assess predictors of gabapentin overuse with or without concomitant opioids.

METHODS: Data were obtained from the Truven Health MarketScan® Commercial Claims and Encounters database for 2013 through 2015. Eligibility criteria were gabapentin utilization, with or without opioids, for 120 days or longer throughout a 12-month observation period. Cohort identification was based on patterns of overuse exceeding thresholds of 3600 mg of gabapentin and/or 50 morphine-mg equivalents of opioids; sustained overuse was defined as three or more quarters exceeding threshold. Diagnostic predictors were measured in the 6 months pretreatment in inpatient (IP) or emergency department (ED) settings. Indications were measured in IP, ED, or ambulatory settings. Logistic regression analyses adjusted for age, sex, indication, use of benzodiazepine or z-hypnotics (i.e., zaleplon, zolpidem, eszopiclone) during gabapentin treatment, pretreatment ED/IP use, and pretreatment diagnoses of anxiety or depression.

RESULTS: Criteria for sustained overuse were met by 2.0% of 44,148 patients treated with gabapentin without opioids and by 11.7% of 15,335 patients treated with concomitant gabapentin-opioid. The top three predictors of sustained overuse for gabapentin-only patients were insomnia (7.0%), euphoria (4.5%), and bipolar disorder (4.5%), and were detoxification (35.6%), altered mental status (26.3%), and addiction (21.6%) for gabapentin-opioid patients. In adjusted analyses, concomitant opioid use multiplied the odds of sustained misuse by 6.32 (95% confidence interval [CI] = 5.80-6.89) and the interaction of addiction with opioid use by 1.88 (95% CI = 1.32-2.66). Among gabapentin-only patients, sustained misuse was predicted by a history of anxiety (odds ratio = 1.56, 95% CI = 1.02-2.38) but not by a history of addiction.

CONCLUSIONS: The likelihood of gabapentin overuse alone is low but significantly increases with concomitant opioid use, especially when coupled with a history of addiction. History of addiction does not appear to increase risk of gabapentin misuse among those with gabapentin alone.