The Association of Gabapentin Use and Dose With Substance Use Disorders Prior to Inpatient Mental Health Treatment: A Cross-Sectional Study

Objective: To investigate the relationship between gabapentin use and dose with substance use disorders (SUDs) prior to inpatient mental health treatment.

Methods: A cross-sectional study was performed in current gabapentin users admitted to inpatient psychiatry services from December 2015 through January 2017 in a large urban teaching hospital. The primary analysis examined rates and doses of gabapentin use in relation to SUD. A multinomial logistic regression was performed to assess a predictive model for SUD in gabapentin users. The secondary analysis examined trends of off-label gabapentin use.

Results: Of 1,483 admissions to inpatient psychiatry services, 345 subjects (23.1%) were prescribed gabapentin as an outpatient prior to admission. Current SUD was identified in 88.1% of the sample, with 65.2% identified as polysubstance positive. Mean daily doses of gabapentin were higher in subjects with positive SUD than in those with no history of SUD. Gabapentin doses ≥ 1,800 mg/d were associated with opiate misuse (P < .001), need for detoxification (P = .004), and positive hepatitis C status (P = .001). Multinomial linear regression revealed that use of gabapentin doses ≥ 1,800 mg/d was predictive of opiate misuse and positive hepatitis C status, with 68.7% positive predictive value.

Conclusion: High-dose gabapentin use can be predictive of opiate misuse disorder. Requests for high-dose gabapentin from patients may signal potential opioid misuse.