Despite the low HIV prevalence among the general population in China, men who have sex with men (MSM) have been disproportionately affected by HIV (1). The nationwide sentinel surveillance system estimated that the HIV prevalence among MSM has increased from 1% in 2003 to 8% in 2014; MSM were the only at-risk population with increasing HIV prevalence during this period (2).
In a number of settings, younger MSM have been observed to be at increasing risk for HIV infection (3–10). Countries in North American, Western Europe, and Australia have reported an increasing proportion of HIV diagnoses among young MSM (3). Young MSM were also reported to have less access to HIV prevention and treatment services than older MSM in both high- and low-income counties (7–10). In China, the number of HIV infections captured by the sentinel surveillance system has increased among young MSM during 2005–2012 (11). Young age is associated with a higher risk of HIV infection among MSM in several longitudinal studies and meta-analysis (12–14). A recent study showed that young MSM had both a higher HIV prevalence (5.4% vs. 3.6%) and incidence [11.8 per 100 person-years (PY) vs. 7.6/100 PY] than older MSM (5). However, some studies found that older MSM at higher risk for HIV prevalence than young MSM (15, 16). A recent systematic analysis of 355 cross-sectional studies in China indicated that MSM who aged 50 years and older had the highest HIV prevalence of 19.3% compared with the overall national prevalence of 5.7% (16) indicating that HIV incidence may not plateau but instead continue at high levels throughout adulthood. Together, these empirical findings suggest that age is a critical component in understanding the epidemic of HIV among MSM that merits further exploration.
In addition to age variation, several meta-analyses assessing HIV prevalence indicate considerable regional variation of the HIV epidemic among MSM in mainland China (11, 16, 17). In general, the southwest has been observed to have the highest HIV prevalence, following by the southeastern coastal regions and northeast regions (11, 16, 17). Differences in the distribution of HIV incidence may vary across regions and by age groups within regions; in a country with over 1 billion persons, it is important to consider regional differences by such essential covariates. Similarly, temporal trends may differ by region. For instance, a repeated cross-sectional study in Beijing showed an rapid doubling of HIV prevalence among MSM (ranged 5–10%) from 2008–2011 (18), in contrast to the sentinel surveillance data in Chengdu, southwest China, which showed a more stable, high HIV prevalence between 2009–2012 (ranged 14–16%) (19). These variations in the HIV prevalence across studies indicate the need for a systematic exploration of HIV epidemic dynamic considering the geographic variation and temporal trends among MSM in mainland China. The HIV prevalence between 2001–2018 among Chinese MSM has been recently summarized (16). The study analyzed 355 cross-sectional studies and estimated that overall national HIV prevalence among MSM was estimated to be 5.7% (5.4–6.1%), with variation by geographic location, age, and other sociodemographic and behavioral factors including education, partners seeking, and condom use (16).
There remains a need to better characterize HIV incidence among MSM in China, with the most recent review conducted over a decade ago, estimating incidence based on three cohort studies and nine cross-sectional studies (20). To optimally inform policy and interventions, there is a need to review and synthesis the HIV incidence among Chinese MSM to aggregate data regarding this key epidemic parameter, including assessment of variation by age groups, regions, and temporal change.
Our study aims to provide comprehensive and updated information on HIV incidence among Chinese MSM, with estimates stratification by age and temporal trends at national and regional levels. This information may inform policy decisions and resource allocations regarding HIV prevention services.
1) What is the age-stratified HIV incidence among MSM residing in mainland China?
2) What are the regional differences in and temporal trends of HIV incidence among MSM residing in mainland China?
3) What factors are associated with temporal changes in HIV incidence in MSM residing in mainland China?