Consistent Use Is Crucial to Efficacy of Condoms in Prevention of STIs
Comparing the sexually transmitted infection (STI) prevalence rates of condom users and nonusers may not be as relevant as comparing those of consistent and inconsistent users, according to a U.S. study of STI clinic visits.1 Fifty-four percent of clinic visits were by patients who reported having used condoms in the previous four months—38% sometimes and 16% at every intercourse. Risky sexual behaviors, such as having ever had more than 10 sexual partners or recently having had new or multiple partners, were reported at a significantly greater proportion of visits by condom users than of those by nonusers. In analyses comparing condom users with nonusers, any condom use did not offer clear protection against STIs; however, in analyses comparing consistent and inconsistent condom use, consistent use significantly reduced the odds of gonorrheal and chlamydial infections among men and women (odds ratios, 0.7-0.9), of trichomoniasis in women (0.9) and of genital herpes in men (0.7).
The researchers used medical records of all females and heterosexual males who had visited a public STI clinic in Denver, Colorado, between January 1, 1990, and December 31, 2001, and reported having had at least one sexual partner in the previous four months. Data included demographic information, lifetime number of sexual partners, number and type of partners in the past four months, STI history, and condom and other contraceptive use in the past four months. The researchers calculated the prevalence of three bacterial infections—gonorrhea, chlamydia and trichomonas—and of three viral infections—genital herpes, genital warts and molluscum contagiosum. For viral infections, only first-time cases of genital warts and herpes and cases in which symptoms had been present for 30 days or less were included. Bivariate and logistic regression analyses were used to determine the predictors of any use and consistent use of condoms, and the associations between levels of condom use and STIs.
Within the study period, there were 126,220 clinic visits by 75,397 individual patients; 39% of visits were made by women and 61% were made by heterosexual men. The median ages of women and of men were 24.5 and 27.0 years, respectively. Overall, 37% of clinic visits were by whites, 35% were by blacks, 25% were by Hispanics and 3% were of by members of other races and ethnicities. Chlamydia was the most prevalent STI among women (10% of visits) and men (12% of visits).
Fifty-four percent of clinic visits were by patients who reported having used condoms in the previous four months—38% sometimes and 16% at every intercourse. Men reported condom use at a significantly greater proportion of visits than did women (56% vs. 51%), although this disparity was attributable to a difference in inconsistent, not consistent, use. Women's use and consistent use of condoms was lower if they had relied on another contraceptive method in the previous four months (43% and 13% of visits, respectively) than if they had not (58% and 19%). In bivariate analyses, condom use was also associated with younger age: Greater proportions of clinic visits by patients younger than 20 than of those by patients 20 or older included reports of condom use (64% vs. 52%) and consistent use (18% vs. 16%). Finally, the prevalence of any use and of inconsistent condom use was greatest among blacks (61% and 44% of visits, respectively), whereas whites had the highest level of consistent use (18% of visits); Hispanics were the least likely to have used condoms, regardless of use level.
Condom use was also related to certain sexual risk behaviors. A significantly greater proportion of visits by condom users than of those by nonusers recorded patients' having ever had more than 10 sexual partners (58% vs. 51%). Furthermore, greater proportions of visits by condom users than of those by nonusers (60-63% vs. 36-41%) and of visits by inconsistent users than of those by consistent users (64% vs. 50-59%) showed patients' having had at least one new partner or multiple partners in the past four months.
In logistic regression analyses of data for men, any condom use was significantly associated with being younger than 20, being non-Hispanic and having had at least one new sexual partner or multiple partners in the past four months (odds ratios, 1.4-2.0); men who had a history of STI had slightly elevated odds of any condom use (1.04). Results for consistent use of condoms were similar, although age was no longer significant and men who had recently had multiple partners were less likely than those who had had a single partner to have always used condoms during intercourse (0.5).
Among women, younger age, being non-Hispanic, having had at least one new sexual partner or multiple partners in the past four months and having had more than 10 lifetime sexual partners were significantly associated with any condom use (odds ratios, 1.1-2.0); women who had used other contraceptive methods in the past four months were less likely than others to have used condoms (0.6). Women 20 or older were more likely than those 19 or younger, and white women were more likely than Hispanics, to have used condoms consistently (1.2 and 1.3, respectively); having recently had multiple partners and used other contraceptive methods were associated with reduced odds of consistent condom use (0.6 and 0.8, respectively).
In analyses controlling for demographic characteristics, sexual risk factors and STI history, male condom users were more likely than nonusers to have genital warts (odds ratio, 1.2), but less likely to have genital herpes (0.8). However, men who used condoms consistently were less likely than those who used them inconsistently to have gonorrhea, chlamydia or genital herpes (0.7-0.9). Among women, any condom use was associated with an increased likelihood of chlamydia (1.2), but a decreased likelihood of gonorrhea (0.9); female consistent condom users were less likely than inconsistent users to have any of the three bacterial STIs studied (0.7-0.9).
The researchers conclude that comparing the STI prevalence rates of condom users and nonusers may not be a useful comparison, given that greater proportions of condom users than of nonusers reported recent risky sexual behavior. They suggest that "the more relevant comparison is within the condom use group, between those who used them consistently and those who did not," in which consistent use offered men and women significant protection against bacterial infections, and protected men against genital herpes.
1. Shlay JC et al., Comparison of sexually transmitted disease prevalence by reported level of condom use among patients attending an urban sexually transmitted disease clinic, Sexually Transmitted Diseases, 2004, 31(3):154-160.