The Effect of Interrupted/Deferred Antiretroviral Therapy on Disease Risk: A SMART and START Combined Analysis

Background Pooled data from the SMART and START trials were used to compare deferred/intermittent versus immediate/continuous antiretroviral therapy (ART) on disease risk. Methods Endpoints assessed were AIDS, serious non-AIDS (SNA), cardiovascular disease (CVD), cancer, and death. Pooled (stratified by study) hazard ratios (HRs) from Cox models were obtained for deferred/intermittent ART versus immediate/continuous ART; analyses were conducted to assess consistency of HRs across baseline-defined subgroups. Results Among 10156 participants, there were 124 AIDS, 247 SNA, 117 cancers, 103 CVD, and 120 deaths. Interventions in each trial led to similar differences in CD4 count and viral suppression. Pooled HRs (95% confidence interval) of deferred/intermittent ART versus immediate/continuous ART were for AIDS 3.63 (2.37-5.56); SNA 1.62 (1.25-2.09); CVD 1.59 (1.07-2.37); cancer 1.93 (1.32-2.83); and death 1.80 (1.24-2.61). Underlying risk was greater in SMART than START. Given the similar HRs for each trial, absolute risk differences between treatment groups were greater in SMART than START. Pooled HRs were similar across subgroups. Conclusions Treatment group differences in CD4 count and viral suppression were similar in SMART and START. Likely as a consequence, relative differences in risk of AIDS and SNA between immediate/continuous ART and deferred/intermittent ART were similar. Clinical Trials Registration NCT00027352 and NCT00867048.