Amid a substantial rise in gabapentin and pregabalin (gabapentinoid) prescribing and increasing concerns with their potential for misuse and diversion, there are anecdotal reports of their use for osteoarthritis. The aim of my thesis was to understand whether osteoarthritis may have contributed to the general rise in the use of the gabapentinoids.
A series of scoping literature reviews summarised the context and potential rationale for the off-label use of gabapentinoids for osteoarthritis. An original analysis of data from the Clinical Practice Research Datalink (CPRD) was then undertaken.
383,680 patients aged over 40 years with a new diagnosis of osteoarthritis recorded between 1995 and 2015 were identified and followed for a median of 5.1 years to their first gabapentinoid prescription or other censoring event. 35,031 (9.1%) cohort members received a gabapentinoid prescription. The crude incidence rate of first gabapentinoid prescription among this cohort of osteoarthritis patients increased from 1.71 (95% CI: 1.37, 2.11) per 1,000 person-years in 2000 to 27.92 (27.06, 28.81) in 2015. Age-standardisation resulted in little change to these estimates. Whilst differences in incidence rates were seen by attained age, time since index osteoarthritis consultation, gender, and geographical region, the increasing trend over time was seen in all strata. The proportions of first gabapentinoid prescriptions in this cohort that could be attributed to osteoarthritis, a licensed indication, or an unlicensed indication were estimated as 9-10%, 11-12%, and 1-2%, respectively. This proportion of attribution remained relatively stable throughout the study period.
Patients with OA have become increasingly likely to be prescribed a gabapentinoid in the past two decades. Whilst this analysis found that the proportion of first prescriptions attributed to OA is approximately 9-10%, an unknown proportion of unattributed prescriptions may also be for OA. With growing concerns regarding their use, gabapentinoid prescribing in this condition requires careful justification.