Vulvodynia is a chronic vulvar pain condition of uncertain etiology1 that affects up to 16% of women in the general population.2 Although the literature provides insight into the physical, sexual, and psychological aspects of this condition, less attention has been given to the relationship between vulvodynia and other chronic medical conditions or to the impact of vulvodynia on the health care community. Individuals with vulvodynia are often reported to seek help from multiple clinicians in an attempt to establish a diagnosis for their condition and effective alleviation of their symptoms.3 Clinical profiles suggest that more than half of women with vulvodynia may suffer from additional chronic health conditions, such as repeated yeast infections, chronic fatigue syndrome, and irritable bowel syndrome.4 However, the literature sheds little light on how women with these characteristics compare with women who seek care for other, general medical conditions.
Case-control studies are a valuable means of identifying clinical predictors and comorbidities of a particular condition, such as vulvodynia. The present case-control study aimed to compare health history and health care use habits of women diagnosed with vulvodynia to those of women in an asymptomatic control group within the context of a care-seeking population.
MATERIALS AND METHODS
In this case-control survey study, women with vulvodynia (cases) and women without vulvodynia or other type of chronic gynecologic pain (controls) completed a confidential survey that assessed demographics (eg, age, race, marital status), health history (eg, medical conditions, obstetric/gynecologic history), use of the health care system (eg, number/nature of doctor’s visits, insurance status), quality of life, and where applicable, history of vulvodynia (eg, nature and duration of pain, exacerbating factors, perceived etiology, impact on daily activities). Institutional review board approval was obtained for the study from University of Medicine and Dentistry of New Jersey (UMDNJ)-Robert Wood Johnson Medical School. Written consent of participants was waived with the acknowledgment that the return of a completed survey implied a subject’s willingness to participate.
The questionnaire used was developed for the purpose of this study. Some of the questions, such as those assessing age, sex, and race, are used routinely in health questionnaires and have face validity. Others, such as medical history, may yield incomplete answers but, nevertheless, are widely used and provide a basis of comparison between cases and controls. Because quality of life scales are usually tailored to capture domains relevant to the health conditions under study, and because we found no previously published scales designed to assess the impact of vulvar pain on quality of life, we used a modified Ladder of Life scale, a scale that has criterion validity for this area.
Subjects were selected from 2 pre-existing study populations. Eligible cases included up to 135 women who participated in vulvodynia research studies at UMDNJ and who had clinically confirmed vulvodynia according to Friedrich’s criteria (vulvar erythema in the absence of other pathology, pain upon vestibular touch/entry, and tenderness with localized pressure to the vestibule),5 with symptoms having at least a 6-month duration. The control population was randomly selected from a group of 1,416 female patients of a multidisciplinary medical practice at UMDNJ who had responded to a 2001 women’s health survey and who, at the time of that survey, had never experienced vulvodynia or any other form of chronic gynecologic pain. As part of the current study, controls were self-identified through a series of screening questions and, to be considered a control, denied experiencing chronic vulvar symptoms lasting 6 months or longer. Cases and controls were frequency-matched on 6 age categories (18–24, 25–34, 35–44, 45–54, 55–64, and 65–80 years). The control population was grouped according to birth date, and 450 names were randomly selected for participation proportionate to the age distribution of the case population.
Subjects were assigned a unique identification number, which was recorded on the survey and linked to names and addresses on a master file. A modified Dillman technique6,7 was used to maximize the response rate. Specifically, an initial survey and letter explaining the study was sent to subjects at week 1. Responses were monitored, and follow-up surveys and letters were mailed to nonresponders at weeks 3 and 5.
Control subjects who reported symptoms consistent with the 2000 International Society for the Study of Vulvovaginal Disease definition of vulvodynia, specifically constant or intermittent burning, stinging, irritation, or rawness of the genital area that may be exacerbated with tampon insertion, speculum insertion during a gynecologic examination, intercourse, or exercise, were excluded from the final study population. Because these women failed to indicate such symptoms in 2001, it is assumed that they developed after that time. Additionally, cases and control subjects with an active vulvovaginal or sexually transmitted infection and/or who were pregnant, as were cases whose vulvodynia was not confirmed by a UMDNJ clinician, were excluded from the study.
Case and control response rates were calculated, and descriptive statistics were generated for all variables assessed. The Kolmogorov-Smirnov test was used to determine whether the distribution of continuous variables (eg, age, quality of life, and level of stress in life) was approximately normal. Mean values were compared using t tests (for those showing a normal distribution), and differences among cases and controls for variables without a normal distribution were tested with the Wilcoxon rank test. The Fisher exact test was used to compare proportions in demographic variables whose subcategories had sparse responses (eg, married, single, divorced/widowed). Univariate analysis was conducted, and with the number of cases and controls available, the study had approximately an 80% power to detect relative risks of 3.64, 2.48, and 2.16 for variables with control group frequencies of 5%, 15%, and 30%, respectively (using a 2-sided α error of 5%).
Although cases and controls were frequency matched on age, a disproportionate number of older controls responded to the survey compared with younger controls. Additionally, mailing addresses were no longer valid for a number of younger control subjects, further reducing the available control population in the younger age groups. Consequently, the case population was significantly younger than the control population. Thus, Mantel-Haenszel calculations and bivariate regression modeling were used to explore the effect of age on individual factors. Age-adjusted odds ratios were calculated and significant univariate associations determined. Statistical significance was established at P < .05. Logistic regression was used to model multiple variables simultaneously and identify significant predictors. The effects of age were studied in 3 categories (18–44 years [premenopausal], 45–54 years [perimenopausal], and 55–80 years [postmenopausal]) in the regression models, with premenopausal women (aged 18–44 years) as the reference group. Data analysis was performed with SPSS 11.0 (SPSS Inc, Chicago, IL).
Questionnaires were mailed to 135 women with vulvodynia (cases) and to 450 women without vulvodynia or other chronic gynecologic pain (controls). Of these, 5 case surveys and 68 control surveys were returned as undeliverable. A 70% case-response rate (91 surveys returned of 130 mailed) and a 72% response rate in the controls (275 surveys returned of 382 mailed) were obtained. A total of 14 cases and 67 controls met exclusion criteria (Fig. 1), leaving us with 77 cases and 208 controls for analysis.
Sixty previously asymptomatic women (21.8%) included in the control mailing indicated that they now had chronic vulvar symptoms consistent with the definition of vulvodynia of the International Society for the Study of Vulvovaginal Disease. These 60 women were excluded from the final control population, but their responses to screening questions were reviewed for informational purposes. Although the majority (56%) had not received a diagnosis for their symptoms, 3 (1%) reported a diagnosis of vulvodynia since 2001. However, we had no clinical confirmation of this diagnosis. Additionally, because many of these 60 women were in their perimenopausal or postmenopausal years, their unexplained vulvar symptoms may be the result of hormonal changes, such as atrophic vaginitis.
The final study population comprised primarily white and highly educated women, with most participants having earned a college or graduate degree (Table 1). Cases were significantly younger than controls (P < .001) and more frequently reported being single, compared with controls, which reported a higher divorce rate. There was a higher proportion of homemakers, students, and retirees among controls, although this difference was not significant.
Although cases and controls reported similar levels of stress (Table 1), cases were more likely (P < .001) to report a worse overall quality of life, as measured on a scale of 1 (worst) to 10 (best). Vulvodynia was significantly associated with worse overall quality of life (Table 1). Moreover, 42% felt out of control of their lives, and 60% felt out of control of their bodies, specifically due to their chronic vulvar pain. Additionally, 90% of cases reported dyspareunia (painful intercourse), and 41% indicated that their condition had severely impacted their sexual lives. (Table 2).
The majority (57%) of cases first experienced vulvodynia symptoms after age 30, although nearly one fifth of the cases had their first symptoms under the age of 20 years (Table 3). “Burning” was the leading pain descriptor (88%), and slightly more than 25% of cases suffered constant vulvar pain. Approximately one third of cases believed their vulvodynia was multifactorial in origin, with stress (25%), yeast infections (29%), unknown causes (38%), and “other factors” (41%) being most commonly cited. Sexual intercourse (75%), use of soaps (41%), tampons (36%), and laundry detergents (35%) were all noted to exacerbate symptoms. Seventy-five percent of cases had consulted 3–9 doctors in their lifetime for their vulvar pain, and one fourth had missed work at least once in the last year due to symptoms of vulvodynia.
Age-adjusted odds ratios demonstrated that controls were significantly more likely than cases to report a history of uterine leiomyomata, hypertension, or pregnancy. Cases, however, were not as sexually active in the 6 months before the survey than controls and reported less use of oral contraceptives than controls (Table 4). Relative to controls, women with vulvodynia had 3 times the rate of comorbid diagnoses of fibromyalgia (odds ratio [OR] 3.8, 95% confidence interval [CI] 1.54–9.55) and irritable bowel syndrome (OR 3.1, 95% CI 1.60–6.05). Of gynecologic conditions assessed, self-reported history of chronic yeast infections and chronic urinary tract infections had the strongest univariate associations with vulvodynia (OR 5.3, 95% CI 2.44–11.62 and OR 9.9, 95% CI 5.23–18.71, respectively). “Chronic” was defined as 3 or more infections within a 12-month period.
With regard to use of the health care system, cases were about 50% more likely as controls to consult a specialist at least once in the last year. Similarly, cases were twice as likely as controls to have seen a mental health professional in the 12 months preceding the survey.
Logistic regression consistently yielded self-reported diagnoses of chronic yeast and chronic urinary tract infections as the strongest predictors of vulvodynia (OR 4.4, P = .031; OR 6.1, P = .000, respectively), with reduced quality of life also being significantly associated with vulvodynia. Consistent with findings from the univariate analysis, vulvodynia had a reduced odds (P < .05) of being associated with pregnancy and uterine leiomyomata, even with age included in the model.
Health care use models indicated that vulvodynia was most strongly correlated with increasing age, and cases were less likely to have health insurance; these findings were statistically significant (P < .05). Although women with vulvodynia also had an increased odds of seeing mental health providers, an obstetrician-gynecologist, and medical specialists at least once a year and of consulting a health care provider an average of more than 3 times per year, these associations were not statistically significant.
Prevalence estimates suggest that women suffering from vulvodynia make up approximately 4% of the general population at a given point in time,2 with the representation as high as 15% in gynecologic clinic populations.8 With a final sample size of 77 clinically diagnosed vulvodynia cases, our study was on par with sample sizes of previous clinic-based studies.8–12 Because both cases and controls had previously participated in UMDNJ studies and considering that all subjects had sought medical care at UMDNJ, effects of response bias were expected to balance out between the 2 groups.
Self-reported pain characteristics of the case population reflect the clinical profiles of vulvodynia patients reported in the literature,1 with vulvar burning the most commonly reported symptom in our population. The negative impact of vulvodynia on a woman’s sexuality is well documented,4,9,13,14 with just under half of cases in our study noting that this condition had an “extreme or disabling” impact on their sexual lives. Despite self-report of painful intercourse, approximately three fourths of cases engaged in sexual activity within the 6 months preceding the survey, observations that are similar to other data that reported nearly two thirds of women with vulvodynia who experienced dyspareunia had engaged in intercourse during the month before the survey.15 Such findings suggest that women with vulvodynia find alternates to “traditional” intercourse in an effort to maintain a fulfilling sexual life and emphasize the need for a thorough sexual history in women with this condition. Because of the high prevalence of dyspareunia in women with vulvodynia, the utility of counseling in noncoital types of sexual exchange should be explored.
Age-adjusted odds ratios indicated that fibromyalgia and irritable bowel syndrome were significantly associated with vulvodynia. The prevalence of these disorders among our overall study population reflects population-based estimates reported in the literature; within the context of cases and controls, the prevalence of fibromyalgia and irritable bowel syndrome in cases is in agreement with national estimates, whereas the prevalence of these 2 conditions in controls is slightly higher than national estimates.16,17 Such multifactorial chronic pain conditions of unknown etiology have been cited as being overrepresented in vulvodynia patients.4,18,19 Arguments have been made to classify such conditions as part of a chronic widespread pain syndrome20 and also to consider vulvodynia within the context of this model.4 These data suggest that women with vulvodynia should be questioned for symptoms of other chronic pain conditions. Furthermore, the potential relationship between these idiopathic, yet highly prevalent, disorders is largely unexplored and may offer an avenue by which to examine the pathophysiology and management of vulvodynia.
Self-report of chronic yeast infections and urinary tract infections (each defined as 3 or more infections within 12 months) were the strongest predictors of vulvodynia in both univariate and multivariate models. Consistent with this finding, nearly 30% of cases believed that their vulvodynia was caused in part by yeast infections. As with any case control study, the potential for recall bias is acknowledged; cases may better remember past exposures, a particular concern in the instance of vulvodynia and vulvovaginal infection history. The literature also supports an association between vulvodynia and yeast infections,4,5,18,21–24 with limited discussion on urinary tract infections,21 but the nature of these relationships is not well understood. Like our current study, previous research has relied upon self-report of infection history without laboratory confirmation of the diagnosis.
Surprisingly, although women with vulvodynia reported a significantly worse quality of life than controls, there were no significant differences in self-reported stress ratings or history of depression. Although vulvodynia is traditionally correlated with high levels of stress and depression,4,5,9,10,25,26 several recent studies have indicated otherwise.9,26 We also suggest that our findings may reflect study location. Participants, both cases and controls, were recruited from an academic medical center in New Jersey, an area characterized by high rates of depression and stress following the 2001 terrorist attacks.27 This may have led to increased rates of stress or depression in the controls in our study.
Chronic pelvic pain places a significant burden on the health care system, with outpatient costs totaling more than $880 million each year.28 Because women with vulvodynia seem to visit multiple clinicians and try numerous treatments,3 it was anticipated that study results would demonstrate that the case population uses the health care system more frequently than controls. Interestingly, this hypothesis was supported only by univariate analysis. When health care variables were considered in conjunction with other factors, they were no longer significantly associated with disease. There was a concern that chronic yeast and urinary tract infections were so strongly correlated with vulvodynia that they prevented health care use variables from remaining in the model, but when a separate model was generated with only health care use variables, these univariate findings still did not emerge as significant predictors.
The failure to identify significant health care use predictors on the multivariate level may reflect the fact that case and control subjects were selected from a care-seeking population. For example, this study could only address the fact that, of those who had received the diagnosis of vulvodynia, they had seen “x” number of providers about their pain. This form of selection bias might reduce any effect of excess medical visits and missed days of work or school by cases because controls also sought care from the same clinical community. To further evaluate such care-seeking factors and explore the burden of vulvodynia on the health care system and society as a whole, health care use trends of women with vulvodynia could be compared with data from the National Health Interview Survey.
This study demonstrates that vulvodynia substantially impacts quality of life and sexual health. Furthermore, the significant associations between vulvodynia and other chronic pain syndromes underscore the need for awareness among health care providers in asking detailed questions about conditions such as fibromyalgia and irritable bowel syndrome. A combination of awareness and better understanding of the relationship between vulvodynia and other (chronic) health disorders may enhance the management of women with this condition.
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