Furthermore, the HET and MSM exposure categories were associated with significantly faster CD4 decline compared with IDUs (−27.6 cells/μL/year; 95% CI: −50.4–−4.9; p = 0.017), and the interaction between the merged MSM/HET exposure category and the date of confirmed infection displayed borderline significance (0.90 cells/μL/year/year; 95% CI: −0.0–1.8; p = 0.056), indicating that the time trend may be less pronounced in these riskgroups.
The decline slope of the CD4 count and the viral setpoint displayed highly significant correlation with the date of diagnosis pointing in the direction of increasing virulence.
The effect of date was strongest in the analysis of IDUs (unadjusted effect: −1.7 cells/μL/year/year, 95% CI: −2.4–−1.1; adjusted effect: −2.0 cells/μL/year/year; 95% CI: −2.6–−1.4; p<0.001), weaker among HETs (unadjusted effect: −1.1 cells/μL/year/year, 95% CI: −2.0–−0.3; adjusted effect: −1.3 cells/μL/year/year; 95% CI: −2.2–−0.3; p = 0.008) and weakest in MSM (unadjusted effect: −0.6 cells/μL/year/year, 95% CI: −1.7–0.6; adjusted effect: −1.01 cells/μL/year/year; 95% CI: −2.16–0.14; p = 0.086), where it failed to reach significance.
The setpoint displayed highly significant correlation with the date of confirmed infection (Spearman's rank correlation test: rho = 0.19, p<0.001; unadjusted effect: 0.062 log10 RNA copies/mL/year, 95% CI: 0.038–0.085), indicating an increasing trend over time.