The Association of HIV Susceptibility Testing With Survival Among HIV-Infected Patients Receiving Antiretroviral Therapy: A Cohort Study

Background: HIV-1 genotypic and phenotypic susceptibility testing (GPT) optimizes antiretroviral selection, but its effect on survival is unknown. Objective: To evaluate the association between GPT and survival. Design: Cohort study. Setting: 10 U.S. HIV clinics. Patients: 2699 HIV-infected patients eligible for GPT (plasma HIV RNA level > 1000 copies/mL) seen from 1999 through 2005. Measurements: Demographic characteristics, clinical factors, GPT use, all-cause mortality, and crude and adjusted hazard ratios (HRs) for the association of GPT with survival. Results: Patients were followed for a median of 3.3 years; 915 (34%) had GPT. Patients who had GPT had lower mortality rates than those who did not (2.0 vs. 2.7 deaths per 100 person-years). In standard Cox models, GPT was associated with improved survival (adjusted HR, 0.69 [95% CI, 0.51 to 0.94]; P = 0.017) after controlling for demographic characteristics, CD4(+) cell count, HIV RNA level, and intensity of clinical follow-up. In subgroup analyses, GPT was associated with improved survival for the 2107 highly active antiretroviral therapy (HAART)-experienced patients (2.2 vs. 3.2 deaths per 100 person-years for patients who had GPT vs. those who did not have GPT; adjusted HR, 0.60 [CI, 0.43 to 0.82]; P = 0.002) and for the 921 triple antiretroviral class -experienced patients (2.1 vs. 3.1 deaths per 100 person-years; adjusted HR, 0.61 [CI 0.40 to 0.93]; P = 0.022). Marginal structural models supported associations between GPT and improved survival in the overall cohort (adjusted HR, 0.54; P = 0.001) and in the HAART-experienced group (adjusted HR, 0.56; P = 0.003). Limitations: Use of GPT was not randomized. Residual confounding may exist. Conclusion: Use of GPT was independently associated with improved survival among HAART-experienced patients.