Objectives: To estimate prognosis by viral subtype in HIV-1-infected individuals from
start of antiretroviral therapy (ART) and after viral failure.
Design: Collaborative analysis of data from eight European and three Canadian
cohorts.
Methods: Adults (N>20 000) who started triple ART between 1996 and 2012 and
had data on viral subtype were followed for mortality. We estimated crude and
adjusted (for age, sex, regimen, CD4þ cell count, and AIDS at baseline, period of
starting ART, stratified by cohort, region of origin and risk group) mortality hazard
ratios (MHR) by subtype. We estimated MHR subsequent to viral failure defined as
two HIV-RNA measurements greater than 500 copies/ml after achieving viral
suppression.
Results: The most prevalent subtypes were B (15 419; 74%), C (2091; 10%), CRF02AG
(1057; 5%), A (873; 4%), CRF01AE (506; 2.4%), G (359; 1.7%), and D (232; 1.1%).
Subtypes were strongly patterned by region of origin and risk group. During 104 649
person-years of observation, 1172/20 784 patients died. Compared with subtype B,
mortality was higher for subtype A, but similar for all other subtypes. MHR for A versus B
were 1.13 (95% confidence interval 0.85,1.50) when stratified by cohort, increased to
1.78 (1.27,2.51) on stratification by region and risk, and attenuated to 1.59 (1.14,2.23)
on adjustment for covariates. MHR for A versus B was 2.65 (1.64,4.28) and 0.95
(0.57,1.57) for patients who started ART with CD4þ cell count below, or more than, 100
cells/ml, respectively. There was no difference in mortality between subtypes A, B and C
after viral failure.
Conclusion: Patients with subtype A had worse prognosis, an observation which may
be confounded by socio-demographic factors.