Summary of Study Population
The records of 3331 participants who initiated second-line ART from May 1, 2010 to May 1, 2016 were eligible for inclusion in this analysis. 1731(52.0%) were female and 1600 (48.0%) were male, 3321 (99.7%) were Han and 3225 (96.8%) were farmer. Among the patients in this study, a large proportion 2650 (79.6%) of the participants were infected HIV through plasma donation, 2802 (84.1%) were HIV-positive longer than 3 years and 2514 (75.5%) received ART before initiating second-line ART. The median CD4+ count was 337 (IQR:229) cells/µl. The demographic characteristics of 3331 participants receiving second-line ART are shown in Table 1.