Prevalence of Vulvodynia

By Marek Jantos Ph.D.

Prevalence studies provide information on current or lifetime baselines whereas incidence studies are more concerned with the rates of increase of a given problem (O’Donohue, 1993). The aim of prevalence studies is twofold: to establish how many women may be experiencing the problem at any one time (point prevalence) or to ascertain how many individuals may have had the problem at some time in their lives (lifetime prevalence). General prevalence studies on vulvodynia have varied significantly in their findings.

T. Galliard Thomas was among the first to comment on the prevalence of chronic unexplained vulvar pain. In his Practical Treatise on the Diseases of Women (Thomas, 1874), Thomas stated that: “this disorder, although fortunately not very frequent, is by no means very rare…that it becomes a matter of surprise that it has not been more generally and fully described” (Thomas, 1874, p. 115). Very little interest was shown in the study of chronic vulvar pain for the next century. This trend only changed in the last two decades with a significant growth in the number of clinical, epidemiological and experimental studies into the prevalence and nature of the disorder.

Early prevalence estimates for female dyspareunia have ranged from a low of 3% to over 50% (Meana & Binik, 1994). In European studies, five percent of sexually active women indicated they had experienced pain during intercourse, while an additional 19% reported pain some of the time (Spira et al., 1993, in Meana & Binik, 1994). In an equivalant study in the U.S. 15% of women reported experiencing pain during intercourse for a part of the preceding 12 months (Laumann et al., 1994).

In 1991, one of the first clinical studies on the occurrence of vestibulodynia (in the study referred to as vulvar vestibulitis syndrome– hereafter abbreviated to vvs), reported a 15% prevalence among a clinical sample of gynecology patients (Goetsch, 1991). The study examined a sample of 210 patients and found that 37% met the diagnostic criteria for vestibulodynia. Of the total group, 50% reported an early onset of symptoms, experiencing discomfort and pain during their teen years, while 21% reported onset post partum. An unexpected finding revealed that as many as 32% of the sufferers reported other female relatives experiencing introital dyspareunia, thereby raising the possibility of a genetic predisposition. However, it is difficult to make any inference about the prevalence of vulvodynia in the general population on the basis of a single cohort of patients attending a gynaecology clinic (Green et al., 2001).

A more recent epidemiological study based on a sample of women living in the Boston area of the United States provided a more reliable prevalence estimate (Harlow & Stewart, 2003). In the Boston sample of approximately 5000 women, 16% of the women reported a lifetime prevalence of chronic vulvar pain akin to vulvodynia. When the study group was limited to women who reported no history of other pelvic disorders (such as endometriosis and polycystic ovaries), the chronic vulvar pain cumulative incidence was 14%. When the population was further restricted to those who reported limitations in normal sexual relations, the cumulative incidence was 10%. In relation to the age of onset, the cumulative incidence was highest before the age of 25 and progressively decreased to age 44, remaining constant through age 64. In relation to age related risk, the authors reported that “we can further conservatively estimate that approximately 5% of women will experience this condition before age 25” (Harlow & Stewart, 2003, p. 87). Furthermore, where vulvodynia was previously thought to be a disorder primarily affecting Caucasian women, a different ethnic trend became apparent, with Hispanic women shown to be at greatest risk (22.7%); white and African American women had the same level of risk (16.2%), while Asian women had the lowest risk (11.1%). The study also found that only 54% of the women reporting a history of vulvar pain had ever sought treatment. However, when symptoms became severe enough to limit intercourse, some 64% of women had sought medical assistance. In summary, the authors suggest that the prevalence of unexplained vulvar pain, meeting the diagnostic criteria of vulvodynia, may be significantly underestimated. The authors ended their report by saying that their findings “bring to the forefront a highly prevalent condition that is associated with substantial disability” (Harlow & Stewart, 2003, p. 87).

In a quasi-experimental study, 105 women with dyspareunia were compared with 105 non-pain controls (Meana et al., 1997). In terms of medical findings, the dyspareunia group were found to present with more physical pathology at the time of the medical examination and reported more psychological symptomatology of distress, depression, phobic anxiety, and negative attitudes towards sexuality and higher interpersonal sensitivity. The dyspareunia group as a whole did not report a higher than average incidence of physical and sexual abuse, past or present. However, among the dyspareunia group, 54% of the women met the diagnostic criteria for vestibulodynia (in the study referred to as vvs). If vestibulodynia, as a single entity, accounts for more than half of the dyspareunia cases, the finding provides further evidence that vulvodynia is the most prevalent form of dyspareunia among women.

Several other studies reported differing prevalence rates. A clinical study on the prevalence of vulvar pain among women attending family planning services and gynaecologic care in an urban minority population found prevalence to be 11% (Levy et al. 2007). The majority of patients (77%) in this study were under 31 years of age. Another study, based on mailed questionnaires to a sample of almost 5000 women, with a 36.8% return rate, found a much lower prevalence of only 4% (Bachmann et al., 2006). Clinical studies from Africa and Europe showed much higher prevalence rates. A general medical clinic in Ghana found the prevalence to be 22.8% (Adanu et al., 2005), and a study of Swedish adolescents attending an adolescent health centre found it to be 34% (Berglund et al., 2002). Thus, the prevalence reports range from 4% to 34%. It should be noted that different sampling techniques were used, with some studies based on clinical samples, others on general population studies, and others on experimental samples; the ages of respondents also varied considerably. As a result the literature on the prevalence of vulvodynia continues to be equivocal.

One consistent trend in these reports is the high prevalence rate of vulvodynia among the younger population of women (Harlow & Stewart, 2003; Levy, 2007, Jantos & Burns, 2007). Until recently the age-specific incidence of these disorders was largely unknown, and there was very little information available regarding any predisposing factors and the age of onset (Harlow & Stewart, 2003). The age related prevalence and risk of onset were deemed as important issues: “it is crucial to investigate how early this pain really begins and how it develops” (Binik, 2000, p. 66).

A recent clinical study of a cohort of 744 Australian women, diagnosed with vulvodynia, examined the age distribution of patients and studied the age of symptom onset (Jantos & Burns, 2007). The study found that 75% of the vulvodynia patients were under the age of 34 years. Prevalence peaked at 24 years of age. The average age of symptom onset was 22.8 years, but for primary vulvodynia cases the average age of onset was 19 years of age. The age of onset ranged from 5.5 years to 45.2 years. The onset of symptoms occurred before the age of 24 years in approximately 50% of the case. The age related risk of symptom onset coincided with a time when many young women were entering into closer relationships.

An unexpected finding in the Australian study was that a significant number of the women reported the onset of symptoms in their early childhood or shortly after puberty, with commencement of tampon use, first medical exam, or with first attempts at sexual activity. These findings, for the first time, highlight the very early onset of symptoms for at least half of the study population. Given that the onset of vulvodynia appears to be unrelated to sexual activity this finding has important implications for the classification of the disorder. Although most evident with commencement of sexual intercourse, it cannot be attributed to solely psychosexual conflict and it is unlikely to meet the criteria of a somatoform disorder (Jantos & White, 1997). A recent retrospective study of vulvodynia in preadolescent girls confirmed the occurrence of vulvodynia in children between ages four to eleven, with duration of pain varying from several months to seven years (Reed & Cantor, 2008). In an early landmark paper, Friedrich noted the disproportionate prevalence of chronic vulvar pain among patients in the 20 -30 age group, with 65% of his study cohort being between the ages of 20 and 40 (Friedrich, 1987). Two other studies suggested that vulvodynia may predominantly affect women under the age of 35 (Rogstat, 2000; Baggish, 1995).

Other studies also noted that women who reported difficulty and pain with first use of tampons were seven times more likely to report chronic vulvar pain than women who experienced little or no difficulty with pain (Harlow & Stewart, 2003). The triggers and risk factors for such an early onset are not clear, but most likely are multi-factorial. Further research is required to identify the specific predisposing risk factors. A range of causes of vulvodynia has been proposed, including embryological, immunological, genetic, hormonal, inflammatory, infectious and neuropathic (Haefner et al., 2005). It is unlikely that there is one single cause.

There is general agreement that the incidence of vulvodynia has increased, not only due to a growing awareness of the problem but also to a real increase in the number of women affected (Moyal-Barracco & Lynch, 2003; Damsted Peterson et al., 2008). The cause of the increase is unknown. Some have suggested that because women of reproductive age are more likely to seek gynaecological care this may result in a higher proportion of younger women being diagnosed (Harlow & Stewart, 2003). However, social change and the redefining of gender roles may also be inextricably linked through growing stresses and pressures which in themselves may contribute to increased disorders of chronic pain. Changes in the social milieu have also helped to overcome past prejudices about women’s sexuality and have encouraged more research. Clinically, a greater move toward cooperation between health disciplines has facilitated earlier recognition of sexual problems, and new technologies, such as the internet, have enabled women to source more information relating to their health and well-being (Leiblum & Rosen, 2000). Patient centered organizations such as the National Vulvodynia Association (NVA) have become an important source of information.