Of 10 916 invited persons (5395 men, 5521 women), 7275 (67%) underwent the initial personal interview and, of these, 76% (2573 men, 2979 women) returned the self-administered questionnaire, yielding overall participation rates of 48% for men and 54% for women. There were some sociodemographic differences between participants and non-participants, with non-participants comprising those who did not participate at all and those who underwent the personal interview but did not return the questionnaire. Participation rates were lower among individuals who were not currently married, those aged <40 or ≥70 years, and those living in the capital area. Moreover, according to information obtained in the personal interview, non-participants had poorer self-rated overall health, shorter school attendance, and shorter post-secondary education than participants (chi-squared tests; all P < 0.01).
Of the 2573 men, 87 (3%) had never had sexual intercourse, and another 141 (5%) did not provide information about their circumcision status. Selected background characteristics for the 2345 sexually experienced men who stated their circumcision status are shown in Table 1. Overall, 125 men (5%) reported that they were circumcised, with little variation by age, membership of a religious community, marital status or household income, although seven of eight Moslem or Jewish participants (88%) were circumcised. A high proportion (29%) of the rather few participants (i.e. 14 of 49) with a non-Danish background were circumcised, and more circumcised than uncircumcised men had attended school for ≥12 years.
General Sexual Experiences There were few differences between the general sexual experiences of circumcised and uncircumcised men (Table 2). Median age at first sexual intercourse was 17 years and median number of sex partners since age 15 years was 4–9 in both groups, but circumcised men were more likely (38%) than uncircumcised men (28%) to report ≥10 sex partners (age-adjusted OR = 1.55; 95% CI 1.06–2.28). The perceived importance of having a good sex life was similar in the two groups, with 90% of circumcised and 89% of uncircumcised men considering a good sex life to be 'important', 'very important' or 'extremely important'. Similar proportions of circumcised (18%) and uncircumcised (15%) men reported no sexual activity with a partner in the last year.
All subsequent analyses were restricted to 1996 men who were sexually active with a partner in the last year and who reported their circumcision status as either circumcised (n = 103, 5%) or uncircumcised (n = 1893, 95%). Of the 103 circumcised men, 15 men (15%) reported the circumcision to have occurred before age 6 months. In both groups, the median frequency of partner-related sexual activity in the last year was one to three times per month.
Difficulties Associated With Sexual Desire and Fulfilment of Sexual Needs Around half of the men reported episodes of low or lacking sexual desire in the last year (Table 3), with no major difference between circumcised and uncircumcised men (ORadj = 1.34; 95% CI 0.85–2.12). Likewise, the two groups were equally likely to report incomplete sexual needs fulfilment in the last year (ORadj = 1.05; 95% CI 0.64–1.72).
Sexual Function Difficulties Considering the sexual function difficulties together revealed no difference between circumcised and uncircumcised men (Table 4). The two most common sexual difficulties, premature ejaculation (reported as an occasional or frequent difficulty by 61%) and erectile difficulties (reported by 40%), were equally frequent in the two groups. Likewise, occasional orgasm difficulties were equally common among circumcised (29%) and uncircumcised (32%) men. However, circumcised men (11%) were more likely than uncircumcised men (4%) to report frequent orgasm difficulties (ORadj = 3.26; 95% CI 1.42–7.47). Proportions reporting occasional or frequent episodes of dyspareunia did not differ between circumcised (10%) and uncircumcised (9%) men (ORadj = 1.31; 95% CI 0.61–2.83); only one circumcised (1.1%) and one uncircumcised (0.06%) man reported frequent episodes of dyspareunia.
Of the 2979 women, 120 (4%) had never had sexual intercourse. Another 322 women (11%) had no spouse, and 303 (10%) either did not know or provided no information about their spouse's circumcision status. Table 1 shows the background characteristics of the 2234 sexually experienced women with a spouse stratified by the reported circumcision status of the spouse. Women with circumcised and uncircumcised spouses did not differ markedly with respect to age, marital status or household income but, as seen for men, women with circumcised spouses were more likely to have a non-Danish background and to have attended school for ≥12 years. However, while fewer women with circumcised (87%) than uncircumcised (94%) spouses were members of a religious community, seven of eight women who were Moslems or Jews (88%) had circumcised spouses.
General Sexual Experiences As for men, the median age at first sexual intercourse was 17 years in both groups (Table 2). Median number of sex partners after age 15 years was 2–3 in women with uncircumcised spouses and 4–9 in women with circumcised spouses. Having a good sex life was 'important', 'very important' or 'extremely important' to 90% of women with circumcised spouses and 87% of women with uncircumcised spouses. Similar proportions of women with circumcised (10%) and uncircumcised (11%) spouses reported no sexual activity with a partner in the last year.
All subsequent analyses were restricted to 1982 sexually active women who reported their spouse's circumcision status to be either circumcised (n = 75, 4%) or uncircumcised (n = 1907, 96%). Age at circumcision in the spouse was known by 71 women, with 20 (28%) reporting circumcision to have occurred before age 6 months. The median frequency of sexual activity in the last year was 1–2 times per week in both groups.
Difficulties Associated With Sexual Desire and Fulfilment of Sexual Needs The majority of women with circumcised spouses (92%) and of women with uncircumcised spouses (84%), reported episodes of low or lacking sexual desire in the last year (ORadj = 2.65; 95% CI 0.80–8.73) (Table 3). Women with circumcised spouses (38%) more often than women with uncircumcised spouses (28%) reported that their sexual needs were incompletely fulfilled (ORadj = 2.09; 95% CI 1.05–4.16).
Sexual Function Difficulties Sexual function difficulties were consistently more often reported by women with circumcised than uncircumcised spouses (Table 5). Sexual function difficulties overall, orgasm difficulties, lubrication insufficiency, dyspareunia and vaginismus were reported to have occurred either occasionally or frequently in the last year by 90, 77, 67, 46 and 9% of women with circumcised spouses as compared with 80, 69, 57, 27 and 4%, respectively, of women with uncircumcised spouses. Most notably, frequent sexual function difficulties overall (31 vs 22%, ORadj = 3.26; 95% CI 1.15–9.27), frequent orgasm difficulties (19 vs 14%, ORadj = 2.66; 95% CI 1.07–6.66) and frequent episodes of dyspareunia (12 vs 4%, ORadj = 8.45; 95% CI 3.01–23.74) were more common among women with circumcised spouses.
The main findings in Table 3, Table 4 and Table 5 were confirmed in 16 robustness analyses (Table 6). Specifically, all showed that circumcised men had around three times greater odds of frequent orgasm difficulties than uncircumcised men. This was the case even in two rather extreme scenarios in which we forced men with unknown circumcision status to produce the most favourable association with circumcision by allocating all such men with sexual difficulties to the uncircumcised group and all those without sexual difficulties to the circumcised group (robustness analysis 5) or by assuming that all men with unknown circumcision status were circumcised (robustness analysis 7). Similarly, women with circumcised spouses had consistently at least four times greater odds of frequent dyspareunia than women with uncircumcised spouses. Additionally, in the analysis restricted to non-Jews and non-Moslems, women with circumcised spouses more often reported episodes of vaginismus (age-adjusted OR = 2.55; 95% CI 1.06–6.18).
Finally, we examined if age at circumcision below or above age 6 months had any measurable impact on our main findings. Specifically, using likelihood ratio tests we compared two regression models with circumcision status treated as either a dichotomous variable (uncircumcised vs circumcised) or a trichotomous variable [uncircumcised vs circumcised in infancy (<6 months) vs circumcised later]. None of the main findings in Table 3, Table 4 and Table 5 differed between men who were, or women whose spouses were, circumcised before age 6 months and those circumcised later (all P > 0.12), suggesting no major impact of age at circumcision on the observed associations.
Int J Epidemiol. 2011;40(5):1367-1381. © 2011 Oxford University Press
Copyright 2007 International Epidemiological Association. Published by Oxford University Press. All rights reserved.