Effect of gabapentin on sexual function in vulvodynia: a randomized, placebo-controlled trial.

BACKGROUND: Sexual dysfunction is common in women with vulvodynia. OBJECTIVE: The purpose of this study was (1) to evaluate whether extended-release gabapentin is more effective than placebo in improving sexual function in women with provoked vulvodynia and whether there is a relationship between treatment outcome and pelvic pain muscle severity that is evaluated by palpation with standardized applied pressure and (2) to evaluate whether sexual function in women with provoked vulvodynia would approach that of control subjects who report no vulvar pain either before or after treatment. STUDY DESIGN: As a secondary outcome in a multicenter double-blind, randomized crossover trial, sexual function that was measured by the Female Sexual Function Index was evaluated with gabapentin (1200-3000 mg/d) compared with placebo. Pain-free control subjects, matched by age and race, also completed Female Sexual Function Index for comparison. RESULTS: From August 2012 to January 2016, 230 women were screened at 3 academic institutions, and 89 women were assigned randomly to treatment. Gabapentin was more effective than placebo in improving overall sexual function (adjusted mean difference, 1.3; 95% confidence interval, 0.4-2.2; P=.008), which included desire (mean difference, 0.2; 95% confidence interval, 0.0-3.3; P=.04), arousal (mean difference, 0.3; 95% confidence interval, 0.1-0.5; P=.004), and satisfaction (mean difference, 0.3; 95% confidence interval, 0.04-0.5; P=.02); however, sexual function remained significantly lower than in 56 matched vulvodynia pain-free control subjects. There was a moderate treatment effect among participants with baseline pelvic muscle pain severity scores above the median on the full Female Sexual Function Index scale (mean difference, 1.6; 95% confidence interval, 0.3-2.8; P=.02) and arousal (mean difference, 0.3; 95% confidence interval, 0.1-0.6; P=.01) and pain domains (mean difference, 0.4; 95% confidence interval, 0.02-0.9; P=.04). CONCLUSION: Gabapentin improved sexual function in this group of women with provoked vulvodynia, although overall sexual function remained lower than women without the disorder. The most statistically significant increase was in the arousal domain of the Female Sexual Function Index that suggested a central mechanism of response. Women with median algometer pain scores >5 improved sexual function overall, but the improvement was more frequent than the pain domain. We hypothesize that gabapentin may be effective as a pharmacologic treatment for those women with provoked vulvodynia and increased pelvic muscle pain on examination.

Recruitment methods in a clinical trial of provoked vulvodynia: Predictors of enrollment.

BACKGROUND: Successful recruitment in clinical trials for chronic pain conditions is challenging, especially in women with provoked vulvodynia due to reluctance in discussing pain associated with sexual intercourse. The most successful recruitment methods and the characteristics of women reached with these methods are unknown. OBJECTIVE: To compare the effectiveness and efficiency of four recruitment methods and to determine socioeconomic predictors for successful enrollment in a National Institutes of Health-sponsored multicenter clinical trial evaluating a gabapentin intervention in women with provoked vulvodynia. METHODS: Recruitment methods utilized mass mailing, media, clinician referrals and community outreach. Effectiveness (number of participants enrolled) and efficiency (proportion screened who enrolled) were determined. Socioeconomic variables including race, educational level, annual household income, relationship status, age, menopausal status and employment status were also evaluated regarding which recruitment strategies were best at targeting specific cohorts. RESULTS: Of 868 potential study participants, 219 were enrolled. The most effective recruitment method in enrolling participants was mass mailing ( p < 0.001). There were no statistically significant differences in efficiency between recruitment methods ( p = 0.11). Relative to clinician referral, black women were 13 times as likely to be enrolled through mass mailing (adjusted odds ratio 12.5, 95% confidence interval, 3.6-43.1) as white women. There were no differences in enrollment according to educational level, annual income, relationship status, age, menopausal status, or employment status and recruitment method. CONCLUSION: In this clinical trial, mass mailing was the most effective recruitment method. Race of participants enrolled in a provoked vulvodynia trial was related to the recruitment method.

Presenting Symptoms Among Black and White Women with Provoked Vulvodynia.

BACKGROUND: The prevalence of vulvodynia has been reported to be lower in black compared to white and Latina women. Use of different terminology to describe vulvar pain symptoms may play a role in lower prevalence. The objectives were to compare pain descriptors used by black and white women with provoked vulvodynia (PVD) to determine the effect of race on symptom reporting. METHODS: Ninety-two women, self-identified as black (n = 55) and white (n = 37) with clinically confirmed PVD completed a questionnaire containing demographic information and vulvar pain characteristics. Variables that were significant with race retained in the logistic regression model were included in multivariate analysis to determine the effect of race on reporting of vulvar pain symptoms. RESULTS: Of statistical significance, white women more often described their pain as burning as compared with black women (84% vs. 22%, p ≤ 0.0001). White women more frequently reported their pain as stinging (51% vs. 29%, p = 0.03) and itching (32% vs. 15%, p = 0.04) as well, whereas there was a trend for black women to more often describe their pain as aching (67% vs. 49%, p = 0.07). Overall, white women were 19 times as likely to report their pain as burning (adjusted odds ratio [aOR] 18.51, 99% confidence interval [CI] 4.46-76.86). CONCLUSIONS: These data suggest that black women are less likely to self-report their vulvar pain as burning, the classic symptom of PVD. Cultural influences and different underlying pain mechanisms may contribute to differences in symptom reporting by race.

Rationale and design of a multicenter randomized clinical trial of extended release gabapentin in provoked vestibulodynia and biological correlates of response.

INTRODUCTION: Few randomized controlled trials (RCTs) have been conducted to establish evidence-based management protocols for provoked vestibulodynia (PVD), a chronic vulvar pain condition affecting approximately 14 million women in the U.S. We describe the rationale and design of an NIH funded multicenter clinical trial utilizing an extended release formulation of gabapentin (G-ER), an intervention that preliminary data suggest may be efficacious for this condition. OBJECTIVES: 1) to determine if pain from tampon insertion (primary outcome measure) is lower in PVD patients when treated with G-ER compared to when treated with placebo and 2) to determine if G-ER reduces vulvar mechanical hyperalgesia, vaginal muscle pain to palpation, the number and intensity of somatic tenderpoints, spontaneous and provoked pain to intradermal capsaicin with an accompanying increase in cardiac beat-to-beat variability and to identify mechanistically-based PVD subtypes. Additional outcomes include subject reported intercourse pain and summative 24-hour pain. METHODS: This 16-week, randomized, double-blind, placebo-controlled, crossover study will enroll 120 women 18 years and older who report tenderness localized to the vulvar vestibule, pain with tampon insertion, and, when sexually active, insertional dyspareunia. Electronically entered daily diaries will be used to determine if pain is lower in PVD subjects when treated with G-ER (up to 3000 mg/d) compared to when treated with placebo. Psychophysiological measures will be obtained at baseline and after 2 weeks at the maximum tolerated dose. CONCLUSION: We will conduct the first multicenter RCT to confirm efficacy of an agent that is currently used in clinical practice for treating PVD.