Demographic features of identified PLWHA infected through commercial and nonmarital noncommercial heterosexual contact in China from 2015 to 2018: a retrospective cross-sectional study.

Background: Understanding the demographic characteristics of people living with HIV/AIDS (PLWHA) infected through commercial heterosexual contact (CHC) or nonmarital noncommercial heterosexual contact (NMNCHC) is important for HIV/AIDS prevention and control.
Methods: Cases reported through the Chinese HIV/AIDS Case Reporting System (CRS) from 2015 to 2018 were analyzed. A descriptive and preliminary inferential analysis were performed for those demographic characteristics deemed of interest.
Results: Overall, 523,121 identified PLWHA between 2015 and 2018 in the CRS were analyzed. The constituent ratio of heterosexual transmission increased from 66.25% in 2015 to 71.48% in 2018. The proportion of CHC heterosexual transmission decreased from 40.18% in 2015 to 37.99% in 2018, while that of NMNCHC increased from 46.33% in 2015 to 49.02% in 2018. PLWHA infected through NMNCHC were significantly younger than those who were infected through CHC (Student's t test, P < 0.0001), with an average age gap ranging from 5.63 (2015) to 7.46 (2018) years, and the average age of both groups increased annually. The frequency of newly identified PLWHA who were infected through CHC had a remarkable increase among the ages of 65 and above. Gender distribution was significantly different between CHC and NMNCHC (χ ²  = 8909.00(2015), 9941.90(2016), 11,004.00 (2017), 12,836.00(2018), all P < 0.0001), and the ratio of men to women in the NMCHC group was 1.50:1 (2015), 1.51:1 (2016), 1.54:1 (2017), and 1.52:1 (2018), while in the commercial heterosexual contact (CHC) group, these ratios were 11.45:1 (2015), 12.08:1 (2016), 12.53:1 (2017), and 13.28:1 (2018). Marital status was significantly different between CHC and NMNCHC (χ ²  = 94.67 (2015), 109.88(2016), 58.18(2017), 152.38(2018), all P < 0.0001). As the educational level improved, the proportion of NMNCHC also increased (Cochran - Armitage test, P < 0.0001).
Conclusions: We found that heterosexual transmission was the primary mode of HIV transmission in China from 2015 to 2018. PLWHA infected through CHC and NMNCHC had different characteristics in age, gender, marital status, and educational level. The frequency of PLWHA infected through CHC increased substantially in the age group of 65 and above. This study provides useful baseline data for future studies on the heterosexual transmission of HIV in China.