Different impact of raltegravir versus efavirenz on CD4/CD8 ratio recovery in HIV-infected patients

Objectives: A low CD4/CD8 ratio during treated HIV identifies individuals with heightened immunoactivation and excess mortality. Whether ART regimens elicit distinct CD4/CD8 ratio recovery remains unknown. We aimed to compare the efficacy of an integrase inhibitor versus a non-nucleoside to normalize the CD4/CD8 ratio. Methods: We conducted a post hoc analysis of the STARTMRK study, a randomized, blinded, double-dummy Phase III trial of raltegravir versus efavirenz, and each in combination with tenofovir/emtricitabine, in treatment-naive HIV-infected adults. Blinding was maintained for the entire 5 year duration of the study. Kaplan-Meier methods for time-dependent variables were used to calculate the rates of CD4/CD8 normalization at different cut-offs and cumulative probabilities. Cox proportional hazard models were used to compare probabilities of CD4/CD8 normalization by treatment arm. Results: A total of 563 patients were analysed; 81% were males and the mean age (SD) was 37 ( 10) years. Raltegravir was associated with higher rates of CD4/CD8 ratio normalization at the >0.4 cut-off ( median time to normalization =56 versus 84 days; P=0.048 by log-rank test). A Cox proportional hazard model stratified based on baseline CD4 counts showed an association between raltegravir and higher rates of CD4/CD8 ratio normalization (HR=1.23; P=0.02). Conclusions: We herein show that normalization of the CD4/CD8 ratio above a clinically meaningful threshold may be dependent on the drug class used. Raltegravir showed faster CD4/CD8 ratio normalization compared with efavirenz, a finding with potential clinical implications. Whether other integrase inhibitors have a similar impact for this outcome remains to be explored.