Temporal role of yeast infections prior to the onset of vulvodynia and after pain development

Vulvovaginal yeast infection has been hypothesized to trigger unexplained chronic vulvar pain (vulvodynia). Yet most studies have failed to describe its temporal role as occurring before or after vulvodynia onset, which if different, may delineate the biological mechanism(s). Using a population-based clinically-confirmed case-control study, we estimated risks of having a history of yeast infection (categorized as: none, 1-4, 5-10, 11-20, 21+) before and after vulvodynia onset for 170 cases who reported age of vulvar pain onset (reference age) and 171 vulvar pain-free controls whose reference age was set to that of a case. Our sample was overwhelmingly White and 30 years old on average. Cases were significantly more likely to have a history of other chronic pain syndromes, anxiety, allergic responses, and abuse. Prevalence of yeast infection prior to reference age was not significantly different between cases and controls (47% vs. 38%, p=0.13), although cases were somewhat more likely to report a greater number of previous infections (p=0.08). Multivariate analyses adjusting for differences listed above reiterated the null findings (adj. OR = 0.88, 95% CI 0.48 - 1.59). In contrast, yeast infections were both more common and frequent in cases subsequent to onset versus a comparable time period in controls. Cases were 3.2x more likely to have had a yeast infection after reference age (95% CI 1.9 – 5.5), and also exhibited a dose-response risk with increasing number of yeast infections by category (adj. ORs=2.0, 4.8, 14, and 16, respectively). Our findings do not support yeast infections as a causative factor in vulvodynia development but rather suggest they occur more commonly after pain onset; this could relate to an altered vulvovaginal milieu as a consequence of vulvodynia, and could potentially relate to pain persistence. These results also highlight the need for accurate assessment of the temporality of yeast infections. Vulvovaginal yeast infection has been hypothesized to trigger unexplained chronic vulvar pain (vulvodynia). Yet most studies have failed to describe its temporal role as occurring before or after vulvodynia onset, which if different, may delineate the biological mechanism(s). Using a population-based clinically-confirmed case-control study, we estimated risks of having a history of yeast infection (categorized as: none, 1-4, 5-10, 11-20, 21+) before and after vulvodynia onset for 170 cases who reported age of vulvar pain onset (reference age) and 171 vulvar pain-free controls whose reference age was set to that of a case. Our sample was overwhelmingly White and 30 years old on average. Cases were significantly more likely to have a history of other chronic pain syndromes, anxiety, allergic responses, and abuse. Prevalence of yeast infection prior to reference age was not significantly different between cases and controls (47% vs. 38%, p=0.13), although cases were somewhat more likely to report a greater number of previous infections (p=0.08). Multivariate analyses adjusting for differences listed above reiterated the null findings (adj. OR = 0.88, 95% CI 0.48 - 1.59). In contrast, yeast infections were both more common and frequent in cases subsequent to onset versus a comparable time period in controls. Cases were 3.2x more likely to have had a yeast infection after reference age (95% CI 1.9 – 5.5), and also exhibited a dose-response risk with increasing number of yeast infections by category (adj. ORs=2.0, 4.8, 14, and 16, respectively). Our findings do not support yeast infections as a causative factor in vulvodynia development but rather suggest they occur more commonly after pain onset; this could relate to an altered vulvovaginal milieu as a consequence of vulvodynia, and could potentially relate to pain persistence. These results also highlight the need for accurate assessment of the temporality of yeast infections.