Vulvar vestibulitis and risk factors: a population-based case-control study in Oslo

Vulvar vestibulitis is a major cause of entry dyspareunia in young women. The aim of this study was to evaluate a self-reported history of bacterial vaginosis, candidiasis, use of oral contraception and nulli-pregnancy as risk factors for vestibulitis. A retrospective examination of medical records was performed for 45 patients with vestibulitis from a vulvar clinic in Oslo, median age 24 years, age range 19-49 years. Four controls per case were selected randomly from the same Oslo source population as the cases. Age-matching was not performed, as matching does not control for confounding in the case-control design. Controls anonymously answered a postal questionnaire, response rate 61%. The crude effect for the major potential predictors for vulvar vestibulitis was estimated, and stratification on age for the major potential predictors. The method of Mantel Haenszel was used to quantify confounders, and control for multi-confounders and the gradient effect of different covariates was performed. The major confounder was age. Independent risk factors for vestibulitis were nulli-pregnancy, odds ratio (OR) 8.4 (95% confidence interval (CI) 2.8-25.2) and bacterial vaginosis, OR 3.37 (95% CI 1.06-10.6). Adjusting for age diluted the effect of oral contraception and frequent treatment for candidiasis. This study is the third case-control study identifying bacterial vaginosis as a risk factor for vestibulitis. Thus, it remains to be investigated whether abnormal vulvo-vaginal microbiota belongs to the aetiology of vulvar vestibulitis.