Endometriosis is characterized by the presence of endometrial-like tissue outside of the uterus and is a chronic disease that serves as the major contributor to pelvic pain and infertility among women.1 Community-based surveys indicate that endometriosis affects 10–15% of all women and 30–50% of symptomatic women during their most sexually active years.2
Improving quality of life is one of the main goals for the treatment of endometriosis.3 Recently, considerable work has been performed to investigate the effect of endometriosis on the quality of life for women. However, the issue of sexual function, which is a major aspect of quality of life, has been poorly studied. Most studies that have explored this parameter have focused mainly on the prevalence of dyspareunia among women with endometriosis4,5 or have evaluated the effectiveness of medical therapies6,7 or surgical therapies for this condition.5,8,9 More than half of women with endometriosis experience dyspareunia during their entire sexual lives, especially those with involvement of the uterosacral ligament.4,5,10 This sexual pain experience may limit women's sexual activities, resulting in a reduction of self-esteem and a negative effect on relationships with partners.11 Furthermore, infertility and depression, which are highly prevalent in women with endometriosis, also are associated with the impairment of sexual function of women.12,13 Thus, a simplistic biometric approach evaluating dyspareunia alone is insufficient for a thorough understanding of endometriosis,14 and a comprehensive and more elaborate assessment of the global effect of the symptoms on women's sexual function using validated questionnaires is urgently needed.14
In contrast to active research of sexual problems throughout the world, studies of female sexual function have been very limited in mainland China. Because of the Asian conservative culture, people in mainland China consider sex to be a taboo topic and therefore are reluctant to discuss it openly. Furthermore, the issue of sexuality tends to be neglected by gynecologists. However, more recently, there has been a growing emphasis on sexual enjoyment in mainland China.15 Thus, the objectives of this study were to estimate the prevalence and correlated factors of female sexual dysfunction in endometriosis in mainland China using a validated questionnaire.
MATERIALS AND METHODS
The study used a cross-sectional design. All participants were recruited among consecutive inpatients scheduled for laparoscopic surgery at Peking Union Medical College Hospital based on signs and symptoms suggestive of endometriosis (ie, dysmenorrhea, nonmenstrual pelvic pain, ovarian cysts, and infertility) between July 2011 and April 2012. The study was reviewed and approved by the institution's Ethics Committee, and all participants provided written informed consent before study entry.
The eligibility criteria were as follows: women who were aged 18–49 years; sexually active during the previous 4 weeks; and those who had laparoscopically diagnosed and histologically confirmed endometriosis. We excluded women who had signs of pelvic inflammatory disease during laparoscopy, symptoms suggestive of interstitial cystitis, those who had received hormone therapies 3 months before surgery, and those who had a history of diabetes mellitus, hypertension, or chronic kidney diseases.
Sample size was calculated based on our pilot study with the first 20 women, which demonstrated a 55% prevalence of female sexual dysfunction in women with endometriosis. Population-based surveys in urban China have shown that 35% of women have at least one persistent sexual dysfunction.15 Thus, a minimal sample size of 95 was calculated to detect a 55% prevalence of sexual dysfunction, with a 10% estimated error and a confidence level of 95%. Considering a 10% refusal rate, a total of 106 participants would be required for survey.
Before surgery, a semi-structured interview was conducted to obtain detailed information on demographic features and disease characteristics. Demographic data included age, height, weight, education level, marital status, years with the current sexual partner, and household yearly income. Body mass index was calculated as weight (kg)/[height (m)]2. The intensity of pelvic pain was quantified using the 10-mm visual analog scale, in which the left extreme represented the absence of pain and the right extreme represented the worst possible pain. A score of 5 or less was considered no pain or mild pain, and score more than 5 was considered moderate-to-severe pain.16 Infertility was defined as the inability to become pregnant after 1 year of unprotected and regular sexual intercourse.
Female sexual dysfunction was assessed using the Female Sexual Function Index developed by Rosen et al17 in 2000. The Female Sexual Function Index is the most commonly used and the "gold standard" instrument to assess sexual function in women who have been sexually active during the previous 4 weeks.17–19 It is a 19-item questionnaire comprising the following six domains: desire (two questions); arousal (four questions); lubrication (four questions); orgasm (three questions); satisfaction (three questions); and pain (three questions). Each domain is scored on a scale of 0 to 6, with higher scores indicating better function for each domain. A domain score of 0 indicates that the women reported no sexual activity during the previous month, and the full score ranges from 2 to 36. The simplified Chinese version of the Female Sexual Function Index was translated and validated by Sun et al,20 and it was found to be reliable and valid in mainland China. We used the widely accepted cut-off score of 26.55 or lower as an indication of female sexual dysfunction.21
During surgery, the laparoscopic findings were recorded, and the extent of endometriosis was determined according to the revised American Society for Reproductive Medicine classification system.22 The diagnosis of endometriosis was confirmed histologically. Deep infiltrating endometriosis was defined as the presence of endometriotic glands and stroma larger than 5 mm under the peritoneal surface. All women underwent operation by the same surgeon (J.-h. Leng) and staging was performed by the same surgeon (J.-h. Leng).
Data were expressed as means±standard deviation, median (interquartile range), or number (percentage) according to the variables. For inferential analysis, an independent t test, Mann-Whitney U test and Pearson' χ2 test were used to compare study variables between cases (total Female Sexual Function Index score 26.55 or less) and controls (total Female Sexual Function Index score more than 26.55), when appropriate. The variables that correlated with cases in the univariable analysis (P<.20) and those thought to be clinically significant were then included in further backward logistic regression analysis to determine the correlated factors of female sexual dysfunction. The regression models eliminated all variables that were not statistically significant at the level of 0.10. Model goodness of fit was examined using the Hosmer-Lemeshow test. All data were analyzed by SPSS 17.0 (SPSS), and P<.05 was considered statistically significant.
Of the 116 inpatients approached for the study, two refused to participate. Three women were excluded because of the histologic diagnosis of pyosalpinx (n=2) or pelvic tuberculosis (n=1). Accordingly, a total of 111 women were eligible for the study, which gave a response rate of 98.2%. Of all of the participants, 81 women had sexual dysfunction, resulting in a crude prevalence of 73.0%. Demographic features and disease characteristics of study participants are shown in Table 1.
Analyses of our data showed that no demographic variables were significantly associated with female sexual dysfunction (Table 2). With regard to disease characteristics, participants with moderate to severe pelvic pain, deep infiltrating endometriosis, and advanced stages were more likely to have sexual dysfunction (P=.001, P=.009, and P=.001, respectively). However, fertility status was not significantly related to sexual dysfunction (P=.49) (Table 2).
Eight variables (age, education, marital status, household yearly income, infertility, pelvic pain intensity, deep infiltrating endometriosis, and revised American Society for Reproductive Medicine stage) were included in our multiple backward logistic regression analysis. Data analysis showed that pelvic pain intensity (P=.014) and revised American Society for Reproductive Medicine stages (P=.020) were significantly associated with female sexual dysfunction. Compared with the participants with no to mild pelvic pain, those with moderate-to-severe pelvic pain had a 3.4-fold (95% confidence interval 1.3–8.8) higher risk of having sexual dysfunction after adjustment for confounding factors. Participants with stage III or IV had a 4.4-fold (95% confidence interval 1.3–15.5) higher risk than those with stages I or II after adjustment for confounding factors. The model fit using the Hosmer-Lemeshow test was adequate (P=.25).
In the present study, we used a validated questionnaire to comprehensively examine the prevalence and correlated factors of female sexual dysfunction in women with endometriosis in mainland China. Our results indicated that sexual dysfunction is highly prevalent in women with endometriosis, especially for those with moderate-to-severe pelvic pain and advanced stages.
Although few studies have investigated the prevalence of sexual dysfunction in women with endometriosis, several studies have clearly indicated that sexual function was impaired in women with endometriosis, especially for the dimension of deep dyspareunia, which affected 60–80% of women undergoing surgery and 50–90% of those using medical therapies.10,11 Our study indicated that the prevalence of sexual dysfunction among the study participants was 73%, which is higher than the prevalence found among general adult women in urban China.15 In addition, this prevalence is even higher than in women treated for cervical cancer.19,23 However, few studies have tried to investigate the prevalence of this issue among women with endometriosis. Therefore, we cannot currently compare our results with other studies.
It is not surprising to find that women with moderate-to-severe pelvic pain were more likely to experience sexual dysfunction. This finding is consistent with that of Verit et al,24 who reported that 67.8% of women with chronic pelvic pain reported sexual dysfunction and that pain intensity was negatively associated with sexual function.24 Recently, another study in Brazil also reported that 39.3% of women with chronic pelvic pain caused by endometriosis were sexually unsatisfied25 and had a decreased frequency of sexual intercourse as well as vaginismus, sexual aversion, and reduced expression of sensuality. Moreover, fear of pain during intercourse also may reduce their sexual desire.
Regarding the revised American Society for Reproductive Medicine stage, which is another related factor, this study found that women with stage III or IV had higher risk of sexual dysfunction. Advanced stages are often associated with the development of considerable adhesions in the pelvic cavity, resulting in the immobilization of pelvic organs during coital activity. As reported in our previous study, the severity of obliteration in the cul-de-sac, which is the main contributor to endometriosis stage, was independently associated with deep dyspareunia.26 Inconsistent findings were reported by Tripoli et al.25 We postulate that the disagreement might be attributable to the differences between participants. All participants in the study by Tripoli et al reported chronic pelvic pain and, as mentioned, pelvic pain intensity is independently associated with female sexual dysfunction.
In contrast to the limited literature arguing that sexual function is primarily associated with deep infiltrating endometriosis,4,5 our findings showed no significant relation after adjusting for the multiple variables. It has been reported that participants with endometriosis infiltrating the uterosacral ligament have less satisfying orgasms and higher sexual pain intensity,4 as well as more severe pelvic pain.27 In the present study, four fifths of women with deep infiltrating endometriosis reported moderate-to-severe pelvic pain (n=45/56), which was significantly higher than those without deep infiltrating endometriosis (n=31/55; P=.008, data not shown). Thus, it can be inferred that deep infiltrating endometriosis is not the main determinant of sexual function in women with endometriosis. Women's quality of life regarding sex may be impaired through the induction of pelvic pain.
We are aware that our study had some limitations. First, the cross-sectional nature of this study does not allow us to infer a direct causal relationship between the variables identified. Thus, a longitudinal study is needed to further investigate any causal relationships among the factors included in this study. Second, the generalization of our results may be limited. Patients included in the study might not be representative of the entire population, because the study was conducted in a referral center for the treatment of endometriosis and, not surprisingly, more than 85% of the patients had stage III or IV. Obviously, the characteristics of the sexual life of this group of women are more severe. Third, we used the widely accepted cut-off value of 26.55 as an indication for the diagnosis of female sexual dysfunction.21 However, different cut-off values of the Female Sexual Function Index exist among populations from different cultural backgrounds.29 Thus, it is critical that cut-off values of Female Sexual Function Index are determined for the Chinese population.
All patients in this study were consecutive inpatients and only two patients refused to participate, which are important strengths of this investigation. This might be because the majority of our participants were well-educated. Second, all participants answered the questionnaire before surgery, so the women and gynecologists were blinded to the presence and site of the endometriotic lesions. Third, to minimize performance bias, all of our patients underwent operation and staging by the same experienced gynecologist (J.-h. Leng), and endometriosis was histologically confirmed for all patients.
In conclusion, our comprehensive study indicates that endometriosis deeply impairs sexual function in women in mainland China. More than two thirds of the women experience sexual dysfunction, especially those with moderate-to-severe pelvic pain or advanced stages. Our results also underscore that female sexual health concerns should be integrated into routine gynecologic care.
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