CD8A and AIDS: We used stratified Cox models to estimate unadjusted and adjusted (for sex, people who inject drugs, ART initiation year, and baseline age, CD4 count, AIDS, duration of ART) all-cause and cause-specific mortality hazard ratios for tertiles of CD4:CD8 ratio (0–0.40, 0.41–0.64 [reference], >0.64) and CD8 count (0–760, 761–1138 [reference], >1138 cells/μL) and examined the shape of associations using cubic splines.