The Characteristics of Gabapentinoid Users with Chronic Non-cancer Pain in the Primary Care of United Kingdom

Background: Gabapentinoids (GPNs) have been increasingly prescribed for chronic non-cancer pain (CNCP) in the past decade in the United Kingdom, despite it being indicated for neuropathic pain only. The insights of characteristics associated with GPN prescribing can help optimise the use of GPNs in the CNCP population.

Objectives: This matched cohort study compared characteristics of GPN users with GPN non-users in the CNCP population.

Methods: Adult (age≥18 years) registrants of Clinical Practice Research Datalink (CPRD GOLD) with a diagnosis of CNCP from 2005 to 2019 and had over 12-month data before the diagnosis were selected as the CNCP population. Of which, GPN users (≥ 1 GPN prescription) were identified and matched 1:5 to GPN non-users by age, gender, and practice on the index date (date of the first GPN prescription). Patients' comorbidities (alcohol usage problem, psychoactive substance misuse, mental health disorder, diabetes, chronic obstructive pulmonary disease and epilepsy) and prescription of pain-related drugs (opioids, benzodiazepines, antidepressants, Z-drugs) in the 12 months before the index date were identified, associated with GPN prescribing in a logistic regression model, and presented in odds ratio (OR) and 95% confidence interval (95% CI).

Results: During the study period, 2,988,582 (13.62% CPRD registrants) patients with CNCP were identified, of which 252,216 GPN users were matched with 1,055,328 non-users with similar demographics. The median age of GPN users was 55 years (interquartile range: 44, 67); 62.83% were female, and the average follow-up was 8.27 years (standard deviation: 4.18). Proportions of patients with comorbidities and pain-related drug prescribing history were higher in GPN users than non-users (e.g. psychoactive substance misuse: 0.59% vs. 0.17%). Diagnosis of neuropathic pain (OR: 10.60, 95% CI: 10.40, 10.79) and historical opioid prescriptions (OR: 2.86, 95% CI: 2.83, 2.84) were positively associated with prescribing GPNs. Being newly diagnosed with CNCP (OR: 0.63, 95% CI: 0.62, 0.63) has a significant negative association with prescribing GPN.

Conclusions: Patients with CNCP, comorbidities and pain-related drug history are more likely to be prescribed with GPNs. Unsurprisingly, neuropathic pain is associated with initiating GPNs. Opioid use history implied GPNs were prescribed to control unsolved pain. Further research is needed to investigate the utilisation pattern of GPNs in patients with CNCP.