Gabapentin May Not Reduce Opioid Use in Chronic Opioid Users

An off-label gabapentin prescription did not reduce opioid dosage in patients with chronic opioid use, according to results of a retrospective cohort study published in Regional Anesthesia and Pain Medicine.

Researchers assessed 172,602 commercially insured patients with chronic opioid use who received a new off-label gabapentin prescription between January 1, 2010, and June 30, 2019.

Of the study cohort, 44.5% of patients were 65 years of age and older and 59.8% were women. Moreover, most patients had arthritis (82.3%) or back pain (68.5%). Approximately 28.7% had a diagnosis of anxiety and 19.4% had a diagnosis of alcohol or substance use disorder.

Opioid dosages were measured using oral morphine equivalents (OME) per day after adding the new off-label gabapentin prescription.

The new off-label gabapentin prescription was associated with a decrease in opioid dosage in 38.8% of patients 6 months after initiating the prescription (from a median of OME per day of 39.1 in the 6 months prior to the first off-label gabapentin prescription to a median OME per day of 25.3 in the 6 months after gabapentin initiation). An increase in opioid dosage was reported in 47.0% of patients (from a median OME per day of 23.2 in the 6 months prior to the first off-label gabapentin prescription to a median OME per day of 37.5 in the 6 months after gabapentin initiation.

There was no change in opioid dosage reported in 14.2% of patients.

Patients taking a new off-label gabapentin prescription who had a history of substance or alcohol use disorders had a decrease in opioid dosage (adjusted OR [aOR], 1.20; 95% CI, 1.16-1.23). Patients with pain disorders who were taking a new gabapentin prescription also had a decreased opioid dosage. This was observed in patients with arthritis (aOR, 1.12; 95% CI, 1.09-1.15); in those with back pain (aOR, 1.10; 95% CI, 1.07-1.12); and in those with other pain conditions (aOR, 1.08; 95% CI, 1.06-1.10).

Study limitations included causality between the addition of a new gabapentin prescription and a change in opioid dosage cannot be definitive due to the retrospective nature of the study. In addition, gabapentin and opioid prescriptions reflect fill rates but may not reflect actual consumption; further, the study of employer-sponsored health insurance claims may not be generalizable to recipients of Medicare and Medicaid, or the uninsured.

The authors concluded, “Findings from this study highlight concerns that off-label gabapentin prescribing in patients with chronic opioid use may not be offsetting opioid analgesia. In some patients, prescribers are not using off-label gabapentin to de-escalate opioid dosage and are contributing to high-risk coprescribing practices associated with respiratory depression and overall mortality.