Gabapentin for the Management of Chronic Pelvic Pain in Women (GaPP1): A Pilot Randomised Controlled Trial

Abstract

Chronic pelvic pain (CPP) affects 2.1–24% of women. Frequently, no underlying pathology is identified, and the pain is difficult to manage. Gabapentin is prescribed for CPP despite no robust evidence of efficacy. We performed a pilot trial in two UK centres to inform the planning of a future multicentre RCT to evaluate gabapentin in CPP management. Our primary objective was to determine levels of participant recruitment and retention. Secondary objectives included estimating potential effectiveness, acceptability to participants of trial methodology, and cost-effectiveness of gabapentin. Women with CPP and no obvious pelvic pathology were assigned to an increasing regimen of gabapentin (300-2700mg daily) or placebo. We calculated the proportion of eligible women randomised, and of randomised participants who were followed up to six months. The analyses by treatment group were by intention-to-treat. Interviews were conducted to evaluate women’s experiences of the trial. A probabilistic decision analytical model was used to estimate cost-effectiveness. Between September 2012–2013, 47 women (34% of those eligible) were randomised (22 to gabapentin, 25 to placebo), and 25 (53%) completed six-month follow-up. Participants on gabapentin had less pain (BPI difference 1.72 points, 95% CI:0.07–3.36), and an improvement in mood (HADS difference 4.35 points, 95% CI:1.97–6.73) at six months than those allocated placebo. The majority of participants described their trial experience favorably. At the UK threshold for willingness-to-pay, the probabilities of gabapentin or no treatment being cost-effective are similar. A pilot trial assessing gabapentin for CPP was feasible, but uncertainty remains, highlighting the need for a large definitive trial.Trial registrationControlled-Trials.com ISRCTN45178534

Is gabapentin effective for women with unexplained chronic pelvic pain?

“…We found one randomised controlled trial comparing gabapentin and amitriptyline for chronic pelvic pain in women with a range of pelvic pathologies, 12 and our own recently published pilot trial (GaPP1) comparing gabapentin with placebo in women with chronic pelvic pain and no identifiable pelvic pathology. 13 In both studies, gabapentin was shown to improve pain scores compared with the control arm; however, neither study has sufficient power to guide practice.…”

Opioids and Alternatives in Female Chronic Pelvic Pain

“…52,53 Data also support the use of gabapentin in patients with CPP, and has been shown to decrease pain levels in patients with pain refractory to nonopioid pain medications. 47,54 A small randomized pilot study evaluated efficacy of gabapentin compared to placebo for treatment of CPP of unknown etiology. Patients taking gabapentin reported decreased pain and improved mood, sustained at 6 months of follow-up.…”

“…Patients taking gabapentin reported decreased pain and improved mood, sustained at 6 months of follow-up. 54 In a study comparing amitriptyline to gabapentin, patients taking gabapentin (alone or combined with amitriptyline) had superior pain reduction with lower VAS scores. 47,55 Side effects were lowest in the gabapentin-only group.…”

New Developments in the Pharmacotherapy of Neuropathic Chronic Pelvic Pain

“…Gabapentin dose was titrated until the patient met a 50% reduction in reported pain (maximum dose 2700 mg/day). In one measure of pain, there was improvement of pain in the treatment group [45]. No current published studies pertaining to the use of pregabalin and CPP in women exist; however, a large randomized controlled trial in men with chronic prostatitis/CPP syndrome (thought to be a neuropathic pain condition) did not show a significant improvement in pain symptoms after 6 weeks of use (up to 600 mg/day) when compared with placebo [46].…”