INDIVIDUAL sexual behaviors have been associated with increased risk of acquiring and transmitting sexually transmitted diseases (STD) including human immunodeficiency virus (HIV).1 We hypothesized that the prevalence of sexual practices may be culturally determined. Thus, some higher-risk sexual practices may be more or less socially acceptable in culturally distinct subgroups and may account for some of the differences in observed STD rates.
The sexual repertoire in a random digit dialing sample of a local urban general population and in an African-American (AA) sample selected from the same population in the United States is described. The results are compared with those reported in the French National Survey2 and the National Health and Social Life Survey from the United States.3
Materials and Methods
Two samples were selected: (1) a random digit dialing sample of all Seattle residents 18 to 39 years of age and (2) a listed AA over sample as previously described.4 Because there may be differences in sexual behavior between AA and white Americans (WA),3 we chose to over sample AA to ensure sufficient numbers to compare the two groups. Respondents self-identified their racial group. For this analysis, the sample was limited to the 356 WA respondents and 140 AA respondents who had ever engaged in vaginal intercourse and who answered questions regarding their usual sexual repertoire with their most recent opposite-sex partner. Twenty-five respondents who had ever engaged in vaginal intercourse were not included because their most recent sex partner was not of the opposite sex.
In the telephone survey, respondents reported the frequency of sexual behaviors during a typical 4-week period with their most recent sex partner, sexual history, partnership characteristics, partner characteristics, STD history, and demographics. A partnership was considered monogamous if the respondent reported that he or she did not engage in sexual activity with anyone else once beginning sexual activity with the partner and that, to the best of their knowledge, their partner was not engaging in sexual activity with anyone else. Interviews averaged 21 minutes in length. The cooperation rate (the ratio of the number of completed interviews to the total number of completed interviews, partially completed interviews, and refusals) was 67.5% for respondents to the random digit dialing sample and 28.2% for the listed AA over sample.
The data were described using contingency tables. Differences between groups were tested using chi-square analysis. We fit a logistic regression model using the backwards elimination procedure to determine the variables that best predicted having a repertoire that included oral, vaginal, and anal intercourse. Data management and most other analyses were performed using SAS for Windows 6.0 (SAS Institute Inc., Cary, NC).5 Odds ratios and their exact 95% confidence intervals (CI) were calculated using EpiInfo (Centers for Diseases Control and Prevention, Atlanta, GA).6
Sexual repertoires during a typical 4-week period with the most recent opposite-sex partner differed significantly by race (p << 0.001). This difference was maintained when stratified by gender, age, employment (Table 1), partnership characteristics (Table 2), and sexual history (Table 3). WA were more likely than AA to report the combination of vaginal and oral intercourse, and AA were more likely than WA to report vaginal intercourse alone. Only AA respondents reported the combination of vaginal and anal sex, but the numbers are small (2%). The combination of vaginal, oral, and anal intercourse was practiced by approximately 5% of each sample (WA: 5.1%; AA: 5.7%). Younger people in the WA sample were more likely to report engaging in vaginal, oral, and anal intercourse (chi-square test for trend, p < 0.001) (Table 1); the reverse was true for the AA sample but was not statistically significant. Only one person, a male WA, reported the combination of anal and oral sex.
WA were more likely than AA to report that their most recent sex partnership was mutually monogamous (76% vs. 59%; p = 0.0002). Persons reporting nonmonogamous relationships were twice as likely to report engaging in the combination of vaginal, oral, and anal sex among both WA (OR = 2.7; CI: 0.9, 7.9) and AA (OR = 2.6; CI: 0.5, 17.1) (Table 2). We observed no differences in sexual repertoire if the respondent reported marriage to or living with the sex partner as married in either sample. However, if the sex partner knew the respondent's family, WA respondents were more likely to report engaging in the combination of vaginal, oral, and anal intercourse than vaginal and oral sex (OR = 1.9; CI: 0.4, 17.5), but the confidence intervals are wide; the reverse was true for AA respondents, but again the numbers are small and the confidence intervals are wide (OR = 0.6; CI: 0.1, 6.5). There were no clear trends with duration of partnership in either sample.
Sexual history and sexual practices were also associated with sexual repertoire (Table 3). Among WA, a lifetime history of more vaginal sex partners was associated with engaging in the combination of vaginal and oral sex and a trend toward an increase in the combination of vaginal, oral, and anal sex, although the numbers are small; the trends are similar in AAs. Increasing condom use was associated with the combination of vaginal and oral sex and decreasing condom use with vaginal sex only among WA; increasing condom use was associated with vaginal sex only among AAs. WA respondents reporting dry sex, intercourse after removing all vaginal secretions, were almost nine times more likely than those not reporting this practice to report the combination of vaginal, oral, and anal sex (OR = 8.7; CI: 2.6, 27.2; AA: OR = 1.8; CI: 0.2, 10.7). Among both WA (OR = 8.4; CI: 2.3, 27.3) and AAs (OR = 14.3; CI: 1.0, 145.1), persons reporting a lifetime sexual history that included both same- and opposite-sex partners were more likely than those with only opposite-sex partners to engage in the combination of oral, vaginal, and anal sex rather than vaginal and oral sex.
To better understand the association of history of same-sex and opposite-sex partnerships with sexual repertoire, the association of this variable with other sociodemographic and behavioral variables was examined (data not shown). Of the 30 individuals included, 21 (68%) were women. A history of same- and opposite-sex partnerships was not associated with age (WA: p = 0.69; AA: p = 0.82), employment status (WA: p = 0.21; AA: p = .26), length of current partnership (WA: p = 0.86; AA: p = 0.57), marriage to current sex partner (WA: p = 0.69; AA: p = 0.64), or practicing dry sex (WA: p = 0.96; AA: p = 0.78). However, persons reporting a history of both same- and opposite-sex partnerships were more likely than those with only opposite-sex partners to report engaging in anal and oral sex with their most recent opposite-sex partner regardless of gender (anal: women 24% vs. 4%, p < 0.001; men: 33% vs. 6%, p < 0.001; oral: women 95% vs. 74%, p = 0.03; men 89% vs. 78%, p = 0.4). Persons with a history of a same-sex partner were also more likely than those with only opposite-sex partners to report that their current relationship was not monogamous (WA: OR = 2.3; CI: 0.9, 5.7; AA: OR = 6.8; CI: 0.6, 338), that their current partner did not know their family (WA: OR = 2.1; CI: 0.7, 5.4; AA: OR = 8.2; CI: 0.9, 100), and to engage in sex during menses (WA: OR = 1.9; CI: 0.7, 5.4; AA: OR = 9.6; CI: 1.0, 458), although the associations were not statistically significant. Persons with a history of a same-sex partner were statistically significantly more likely than those with only opposite-sex partners to report more vaginal sex partners. (No person in this category in either sample reported fewer than three sex partners; WA: p = 0.002; AA: p = 0.07.) Same-sex experience was not associated with condom use (WA: p = 0.9; AA: p = 0.5).
To determine variables most strongly predictive of engaging in the combination of vaginal, oral, and anal intercourse, a logistic regression model was fit to both samples combined. Race, age, current employment, lifetime number of vaginal sex partners (transformed using the natural log), engaging in dry sex or sex during menstruation with most recent partner, length of most recent partnership, monogamy, having same and opposite-sex partners, and whether the partner had met the respondent's family or whether the respondent was married to the partner or living as married were included in a stepwise logistic regression using the backward elimination procedure (data not shown). Age (OR = 1.1; CI: 1.0, 1.2), engaging in dry sex (OR = 8.4; CI: 3.1, 22.8), having a non-monogamous relationship (OR = 2.4; CI:1.0, 5.7), having both same- and opposite-sex partners (OR = 15.4; CI:5.1, 47.0), having a partner who knew the respondent's family (OR = 6.3; CI:1.5, 27.0), and not being married to or living as married (OR = 3.2; CI:1.2, 8.1) were significantly associated with engaging in the combination of oral, vaginal, and anal sex.
Among this local general population sample of WA and AA who reported ever engaging in vaginal intercourse, having both same and opposite-sex partners was strongly associated with engaging in the combination of vaginal, oral, and anal sex with their current opposite-sex partner. Persons in our study with a history of same- and opposite-sex partners were also less likely than those reporting only opposite-sex partners to report that their current sexual relationship was monogamous. In addition, they reported a greater lifetime number of vaginal sex partners but were no more likely than those with only opposite-sex partners to use condoms. This combination of factors suggests a high-risk profile for both acquiring and transmitting STDs. However, given the cross-sectional nature of our data we can not determine whether the same-sex experience led to more varied repertoire or whether more varied repertoire led to same-sex experience.
Consistent with the National Health and Social Life Survey,3 sexual repertoire significantly differed by race even after stratifying by sociodemographic, partnership, and sexual history variables. Oral sex was less common among AAs, and AAs were more likely to report engaging in vaginal intercourse alone. As found in the French National Survey,3 only a few repertoires were observed in both groups, and length of partnership, and marriage to or living with the partner was associated with repertoire.
The consistency of our results with other studies is reassuring. The low cooperation rate for the AA-listed sample (28.2%) raises questions about both the reliability and validity of the parameter estimates. The cooperation rate for the random digit dialing (RDD) sample (67.5%) is comparable with the 65 to 70% obtained in other RDD sexual research surveys.7 However, even with a much higher cooperation rate it is possible to obtain biased estimates.
We could not compare the frequency of specific practices directly to the National Health and Social Life Survey3 or the French National Survey2 because these surveys report sexual practices at last intercourse and we measured sexual practices during a typical 4-week period. Although such a comparison would be of interest, patterns of sexual behavior observed in national populations may not apply to local populations because of variation in such diverse factors as sexual norms, sex ratio, ethnicity, and patterns of partner recruitment.8
In conclusion, the 5% of the population engaging in the combination of vaginal, oral, and anal intercourse were also more likely to report other behaviors putting them at a higher risk of acquiring or transmitting a sexually transmitted disease. These findings highlight the need for a greater understanding of sexual repertoire both for planning and targeting appropriate STD interventions.
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