Vital Surveillances: Comparative Analysis of Epidemiological Features of HIV/AIDS Cases Aged Over and Under 50 Years Old — China, 2010–2022

Data from the Chinese HIV/AIDS Comprehensive Response Information Management System (CRIMS) were utilized to assess the epidemiological profile of newly diagnosed HIV infections in individuals aged 15–49 years and ≥50 years. Medical facilities and the regional Centers for Disease Control (CDCs) use the CRIMS to report cases. The permission to access data in the CRIMS database was obtained from the National Center for AIDS/STD Control and Prevention, China CDC. All newly reported PLWHA in the CRIMS between 2010 and 2022 were included in our study. The detection rate was calculated as the number of newly identified cases within a given year divided by the respective population size for that age bracket.

For the statistical analysis, Chi-square tests were employed to examine differences by using SPSS software (version 24.0, IBM Inc., Armonk, NY, USA). To assess trends in standardized incidence rates, we conducted Joinpoint regression analysis with the Joinpoint Regression Program (version 4.9.0.0, March 2021; Statistical Methodology and Applications Branch, Surveillance Research Program, National Cancer Institute), devised by Kim et al. (4). Additionally, the annual percent change (APC) was determined through Joinpoint regression analysis. The years were designated as the independent variable (x_i), and the number of HIV/AIDS cases was considered the dependent variable (y_i). Gender and age were classified as categorical variables. The grid search method (GSM) was applied to detect turning points and model parameters. Furthermore, the modified Bayesian information criterion (MBIC) was employed to ascertain the optimal model. The model with the smallest MBIC value was selected as the optimal one for analyzing the time trend of new detection rates and calculating the APC. A significance threshold (α) was set at 0.05, with a P-value of less than 0.05 indicating statistical significance.

In China, the number of newly reported HIV/AIDS cases in the 15–49 age group increased from 51,436 in 2010 to 55,397 in 2022, while it increased from 11,751 in 2010 to 51,856 in 2022 in the group aged ≥50 years. In the male group, the percentage of individuals aged 50 and older with HIV/AIDS saw a significant increase from 19.57% in 2010 to 44.39% in 2022 (χ²=30,268.80, P<0.01). Similarly, among females, the percentage of HIV/AIDS in those aged 50 and above rose markedly from 16.26% in 2010 to 62.78% in 2022 (χ²=12,529.83, P<0.01). Among new diagnoses in China, males aged between 15 and 49 accounted for 79.24% of cases, resulting in a gender ratio of 3.82∶1. Among the demographic aged 50 and older, 73.34% of cases were male, with a reduced gender ratio of 2.75∶1 (Figure 1).

Figure 1. 

Frequency of HIV/AIDS cases in individuals aged 15–49 and ≥50 years, and proportion of HIV/AIDS cases in individuals aged ≥50 years between male and female in China, 2010–2022.

Abbreviation: HIV=human immunodeficiency virus; AIDS=acquired immunodeficiency syndrome.

The trend in detection rates of HIV/AIDS case from 2010 to 2022 was rising, with a little decline after 2019. For males, the detection rate of HIV/AIDS cases in the ≥50 age group exceeded that of the 15–49 age group around 2017. Conversely, in females, the detection rates remained relatively stable across both age groups, although the detection rate for those aged 50 and over was greater than that for the 15–49 cohort beginning around 2014 (Figure 2). A comparative analysis of the annual new detection rates for HIV/AIDS cases across different gender and age groups revealed an upward trend for males aged 50 and above, with rates climbing from 0.5 per 10,000 in 2010 to 2.2 per 10,000 in 2019, before the trend reversed and fell to 1.5 per 10,000 by 2022. Joinpoint regression analysis indicated an APC of 18.3% [95% confidence interval (CI): 16.1%, 20.6%] from 2010 to 2018 and an APC of −8.0% (95% CI: −11.2%, −4.6%) from 2018 to 2022. In females aged 50 and over, detection rates rose from 0.2 per 10,000 in 2010 to 0.8 per 10,000 in 2019, then similarly reversed, decreasing to 0.6 per 10,000 in 2022. Joinpoint regression analysis for this group showed an APC of 19.2% (95% CI: 17.2%, 21.4%) from 2010 to 2018 and an APC of −6.7% (95% CI: −9.6%, −3.7%) from 2018 to 2022 (Table 1).

Figure 2. 

The trending change in the detection rate of HIV/AIDS cases in individuals aged 15–49 and ≥50 years old in China, 2010–2022.

Abbreviation: HIV=human immunodeficiency virus; AIDS=acquired immunodeficiency syndrome.

In 2022, significant disparities were observed among different age cohorts, distinguished by gender. Our analysis revealed that men and women across these groups presented statistically significant dissimilarities in terms of educational background, marital status, occupation, transmission route, site of diagnosis, and region (P<0.01). Furthermore, when comparing age groups, distinct patterns in transmission routes emerged (χ²=72,936.81, P<0.01).

In the 15–49 age category, heterosexual transmission was predominant, accounting for 55.62% (30,813/55,397) of cases. This trend was even more pronounced in those aged 50 and above, with heterosexual transmission representing 90.16% (46,754/51,856) of instances. Notably, among men aged 15–49, homosexual transmission constituted a significant proportion at 50.13% (23,463/46,802). In contrast, the rate for homosexual transmission was markedly lower in men aged 50 and above, at 11.04% (4,125/37,358).

In terms of female cases, however, non-mainstream non-commercial heterosexual contact (NMNCHC) (12,595/22,448, 56.11%) was identified as the primary transmission route for both age brackets, at 70.65% and 64.33%, respectively, as detailed in Table 2.

Our study revealed that the detection rates of HIV/AIDS among individuals aged 50 and older have surpassed those in the 15–49 age group in recent years in China. This aligns with research indicating that the proportion of PLWHA who are aged 50 years or older has been on an annual rise (5). Factors contributing to this trend include high-risk sexual behaviors and a deficit in HIV-related knowledge and awareness among this demographic (6). Consequently, the rising trend underscores the need for heightened attention and targeted interventions for the population aged 50 years and above.

The observed prevalence of newly identified HIV infections across two distinct age demographics exhibited an increasing trend prior to the year 2019, followed by a notable decline commencing in 2020. This pattern not only captures the ongoing dynamics of the epidemic but is also influenced by the enactment of comprehensive prevention and control tactics aimed at broadening diagnostic evaluations (7). These measures have contributed to the identification of a higher number of HIV-positive individuals. Moreover, the downward trend could be indicative of advancements in prevention and control efforts (3), as well as the consequences of intensified COVID-19 mitigation policies during the same timeframe. These policies, which curtailed movement and social gatherings, may have indirectly led to a reduction in high-risk behaviors (8).

In China, there are distinct variations in the transmission routes and regional distribution of HIV cases. Men aged between 15 and 49 years are at an elevated risk of contracting HIV through homosexual contact, whereas the primary transmission route for elderly men is CHC. Additionally, there is a rising trend in HIV/AIDS cases among women aged 50 years or older, which can be partly attributed to the fact that post-sterilization, older women may not feel the need to engage in contraceptive practices (9).

Moreover, the data reveals a significant proportion of HIV/AIDS cases with critically low CD4+ cell counts (below 200 cells/μL), indicating a substantial number of undiagnosed cases. This underscores the urgent need for intensifying efforts to identify and diagnose individuals living with HIV/AIDS.

This study has some limitations. The data from CRIMS were used in this study to conduct a macro-level analysis. However, we were unable to investigate the behavioral characteristics of PLWHA in-depth due to monitoring data limits.

In conclusion, there are differences in demographic characteristics and transmission routes between PLWHA aged over and under 50 years old. The proportion of HIV/AIDS cases among people aged ≥50 years showed an increasing trend. Further research is also required to identify the factors that contribute to the HIV epidemic in various age groups. We should focus on the elderly population and establish specific prevention and control measures for them.