Background:
The HIV epidemic is increasing among Men who have Sex with Men
(MSM) and the risk for AIDS defining cancer (ADC) is higher among them.
Objective:
To examine the effect of MSM and CD4+ count on time to cancer AIDS (ADC) and noncancer
AIDS in competing risks setting in the HAART era.
Method:
Using Ontario HIV Treatment Network Cohort Study data, HIV-positive adults diagnosed
between January 1997 and October 2012 having baseline CD4+ counts ≤ 500 cells/mm3 were evaluated.
Two survival outcomes, cancer AIDS and non-cancer AIDS, were treated as competing risks.
Kaplan-Meier analysis, Cox cause-specific hazards (CSH) model and joint modeling of longitudinal
and survival outcomes were used.
Results:
Among the 822 participants, 657 (79.9%) were males; 686 (83.5%) received anti-retroviral
(ARV) ever. Regarding risk category, the majority (58.5%) were men who have Sex with men
(MSM). Mean age was 37.4 years (SD = 10.3). In the multivariate Cox CSH models, MSM were
not associated with cancer AIDS but with non-cancer AIDS [HR = 2.92; P = 0.055, HR = 0.54; P =
0.0009, respectively]. However, in joint models of longitudinal and survival outcomes, MSM were
associated with cancer AIDS but not with non-cancer AIDS [HR = 3.86; P = 0.013, HR = 0.73; P =
0.10]. CD4+ count, age, ARV ever were associated with both events in the joint models.
Conclusion:
This study demonstrates the importance of considering competing risks, and timedependent
biomarker in the survival model. MSM have higher hazard for cancer AIDS. CD4+ count
is associated with both survival outcomes.
Multiple-Imputation-Based Residuals and Diagnostic Plots for Joint Models of Longitudinal and Survival Outcomes