title: 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 (300-2700 mg 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.
authors.affiliation: Centre for Population Health Sciences, University of Edinburgh, Edinburgh, Lothian, United Kingdom.
authors.forename: Steff C
authors.initials: SC
authors.lastname: Lewis
authors.affiliation: Applied Health Sciences, University of Aberdeen, Aberdeen, Grampian, United Kingdom.
authors.forename: Siladitya
authors.initials: S
authors.lastname: Bhattacharya
authors.affiliation: Health Economics and Health Technology Assessment Institute of Health and Wellbeing, University of Glasgow, Glasgow, Lanarkshire, United Kingdom.
authors.forename: Olivia
authors.initials: O
authors.lastname: Wu
authors.affiliation: Nuffield Department of Obstetrics and Gynaecology, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom.
authors.forename: Katy
authors.initials: K
authors.lastname: Vincent
authors.affiliation: Gynaecology, Aberdeen Royal Infirmary, Aberdeen, Grampian, United Kingdom.
authors.forename: Stuart A
authors.initials: SA
authors.lastname: Jack
authors.affiliation: MRC Centre for Reproductive Health, University of Edinburgh, Edinburgh, Lothian, United Kingdom.
authors.forename: Hilary O D
authors.initials: HO
authors.lastname: Critchley
authors.affiliation: Applied Health Sciences, University of Aberdeen, Aberdeen, Grampian, United Kingdom.
authors.forename: Maureen A
authors.initials: MA
authors.lastname: Porter
authors.affiliation: MRC Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, Lothian, United Kingdom.
authors.forename: Denise
authors.initials: D
authors.lastname: Cranley
authors.affiliation: Department of Anaesthesia and Pain Medicine, Royal Infirmary of Edinburgh, Edinburgh, Lothian, United Kingdom.
authors.forename: John A
authors.initials: JA
authors.lastname: Wilson
authors.affiliation: MRC Centre for Reproductive Health, University of Edinburgh, Edinburgh, Lothian, United Kingdom.
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Horne
mesh_terms: D000293:Adolescent; D000328:Adult; D000588:Amines / Q000191:economics / Q000627:therapeutic use*; D000700:Analgesics / Q000191:economics / Q000627:therapeutic use*; D059350:Chronic Pain / Q000188:drug therapy / Q000191:economics; D003362:Cost-Benefit Analysis; D003509:Cyclohexanecarboxylic Acids / Q000191:economics / Q000627:therapeutic use*; D005260:Female; D000077206:Gabapentin; D006801:Humans; D015233:Models, Statistical; D017063:Outcome Assessment, Health Care; D059408:Pain Management / Q000379:methods; D017699:Pelvic Pain / Q000188:drug therapy* / Q000191:economics; D010865:Pilot Projects; D011446:Prospective Studies; D055815:Young Adult; D005680:gamma-Aminobutyric Acid / Q000191:economics / Q000627:therapeutic use*
chemical_list: D000588:Amines; D000700:Analgesics; D003509:Cyclohexanecarboxylic Acids; D005680:gamma-Aminobutyric Acid; D000077206:Gabapentin