| Objective: This study assessed efficacy and adherence for the HIV pre-exposure prophylaxis clinical trial(Pr EP) among HIV-seronegative men who have sex with men(MSM) in western china, and explored the effect of the adherence to oral Pr EP on HIV new infection reduction and sexual risk compensation, so as to provide basis and reference for the future study of Pr EP strategies among MSM in china.Methods: Using non-probability sampling for recruitment, we conducted a clinical trial on oral Pr EP to prevent HIV new infection among HIV-seronegative MSM in Chongqing, Guangxi, Sichuan, and Xinjiang region. After screening and enrollment, we randomly assigned the eligible subjects based on the inclusion and exclusion criteria to daily oral TDF arm(one dose daily) or intermittent oral TDF arm(one dose up to 48-24 hours before sex, and one within 2 hours after sex, without using more than one dose in a 24 hour period) or blank control arm. All subjects received HIV testing, risk-reduction counseling, condoms, and management of sexually transmitted infections. Then subjects were interviewed face to face and tested for HIV every 3 months during a 2 year follow-up period. Multivariate Cox regression analyses were employed to examine the influence of drug regimen and medication adherence to oral Pr EP on reducing HIV acquisition. And multivariate generalized estimating equations(GEE) were used to analyze the influence of time and medication adherence to oral Pr EP on anal condom usage during the follow-up period.Results:(1) A total of 2422 MSM were recruited for screening, and 1914 eligible MSM were enrolled. By the end of clinical observation, 429 MSM(22.4%) did not complete at least one follow-up, and 181 reported having no sex during the follow-up period. Given that, 1304 subjects were finally included for analysis, with 388 assigned to daily oral Pr EP, 473 to intermittent oral Pr EP and 443 to blank control.(2) The study subjects were followed for 1568.5 person years(median, 15 months; minimum, 3 months; maximum, 24 months) and 96 HIV seroconvesion were found during follow-up. The overall HIV incidence was 6.12 per 100 person years, 6.78 per 100 person years(31/457.5 person years) for daily oral Pr EP arm, 5.34 per 100 person years(31/580 person years) for the intermittent oral Pr EP arm and 6.4 per 100 person years(34/531 person years) for the blank control arm. No significant difference was found among the three groups(2c=1.1195, P= 0.5713).(3) Under the good medication adherence to the regimen, the HIV incidence was 3.2 per 100 person years(8/249.75 person years) for daily oral Pr EP arm and 1.33 per 100 person years(4/299.75 person years) for the intermittent oral Pr EP arm. Compared to the blank control arm, there was a 50% reduction in the incidence of HIV in daily oral Pr EP arm and 79.22% in the intermittent oral Pr EP arm. Multivariate Cox regression analysis indicated that the risk of HIV new infection among MSM was 0.159 times(95%CI=0.046-0.556) in the intermittent oral Pr EP arm and 0.355 times(95%CI=0.131-0.960)in the daily oral Pr EP arm, compared to the blank control arm.(4) According to the minimum protective medication regimen, subjects of medication were divided into compliance and noncompliance two groups. The HIV incidence was 3.0 per 100 person years(20/665.75 person years) in compliance group and 10.84 per 100 person years(38/350.5 person years) in noncompliance group, the former indicating a 53.1% reduction and the latter a 69.4% increasing in the incidence of HIV compared to the blank control group. Multivariate Cox regression analysis indicated that the risk of HIV new infection among MSM in the compliance group was 0.371 times(95%CI=0.194-0.710) of that in the blank control group while there was no significant difference between the noncompliance group and the blank control group(AHR=1.618,95%CI=0.965-2.713). In addition, MSM who received HIV testing in recent year had lower risk of HIV new infection compared with those who did not(AHR=0.493, 95%CI=0.294-0.826), and those who were diagnosed with STD in recent half a year were more likely to be infected with HIV(AHR=2.882, 95%CI=1.587-5.235).(5) During the follow-up period, the median number of sexual partners basically remained one and the median number of insertive sexual behaviors basically remained two no matter in which group. There was no significant difference in sexual partner number and insertive sexual behavior number between treatment and control groups(P>0.05). But compared to the blank control group, the treatment groups had lower anal condom usage rate(H=12.0845, P=0.0024), especially at the 3th, 12 th, 15 th, 18 th month. Multivariable GEE analysis found that the anal condom usage rates were not changed significantly over time in the Pr EP trial(Z=0.536,P=0.464) while MSM in the noncompliance group had lower anal condom usage rate compared to the blank control group during the follow-up period(Z=4.155,P=0.042).Conclusion:(1) The HIV incidence rate is relatively high among MSM in western china, especially in Chongqing and Sichuan region, indicating a grim and challenging situation of prevention and control.(2) Oral Pr EP can effectively reduce HIV acquisition among HIV-seronegative MSM in china, and Pr EP efficacy is strongly related to adherence.(3) Further study on adherence improvement strategy of Pr EP is urgently needed while the implementations of current HIV/AIDS integrated prevention and control strategy in high epidemic areas also need to be strengthened. |
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