Baseline characteristics of the 1264 participants from whom a urethral swab was collected at the 21-month visit are reported by randomization group in . These characteristics are similar and not statistically different except for HIV status. The mean (median) duration in days of follow-up among the intervention and control group was 644 (637) vs. 649 (637), respectively.
Background characteristics, reported sexual behavior and HIV prevalence at the 21-month visit
presents the intention-to-treat univariate association between HR-HPV prevalence and male circumcision at the scheduled 21-month visit. HR-HPV prevalence was significantly lower among men of the intervention group. As indicated in , the percentage of each of the 13 HR-HPV genotypes was always lower among men of the intervention group than among men of the control group. In the intention-to-treat comparison, the difference was significant for genotypes 18, 31, 45, 52, 56, 58, and 68.
Association between High-risk Human Papillomavirus (HR-HPV) prevalence and male circumcision.
Distribution of the high-risk HPV genotypes as a function of randomization group.
shows that the protective effect of MC on HR-HPV is higher in the as-treated analysis than in the intention-to-treat analysis. The protective effect is also higher in both analyses when controlling for potential confounders, including HIV status and reported sexual behavior cofactors. HR-HPV was associated with HIV status in both analyses with aPRRs of 2.2 (95%CI 1.5–3.3) and 2.2 (95%CI 1.5–3.2), respectively. When those who seroconverted for HIV during follow-up were excluded from the analysis, the results indicated in remained practically unchanged with P-values less than 0.009 and a relative variation of the PRRs and aPRRs of less than 5.2%. This suggests that the effect of MC on HR-HPV is independent of the effect of MC on HIV. The aPRRs were almost identical when the analyses were adjusted for the propensity score in addition to the other covariates.
Multiple HR-HPV prevalence was 7.0% (89/1267; 95% CI: 5.7% – 8.6%). It was significantly lower among men of the intervention group compared with men of the control group (4.2% vs. 9.9%; PRR=0.43; 95% CI: 0.28 – 0.66; P<0.001). Among men with at least one HR-HPV, multiple HR-HPV prevalence was also lower among men of the intervention group (44.3% vs. 28.7%; PRR=0.64; 95% CI: 0.45 – 0.94; P=0.020).
As indicated in , NG prevalence was similar in the two groups. Among men of the control and intervention groups, median number of lifetime partners was 4.1 and 4.2, respectively, (P=0.49; Kruskal-Wallis test) and the proportion of consistent condom users was 17.4% and 19.7%, respectively, (P=0.45; Fisher exact test). These findings suggest that the protective effect of MC on HR-HPV cannot be attributed to a difference of sexual behavior between the two groups.
Association between Neisseria gonorrhea (NG) prevalence and male circumcision.
During the study period, 371 men of the control group were circumcised and had a urethral swab taken before and after male circumcision. The average (median) duration between the two swab collections was 59 (43) days. As expected, the HR-HPV prevalence was the same between the two samplings (23.7% vs. 23.9%; P=1.0; Sign test). The proportion of males with multiple HR-HPV genotype infections was not significantly different (10.2% vs. 12.1%; P=0.40; Sign test). These results indicate that the as-treated effect of male circumcision on HR-HPV prevalence shown in cannot be attributed to an easier detection of HR-HPV by urethral swabbing in uncircumcised men compared with circumcised men.