A total of 118 participants were recruited. For the current analysis, forty-seven participants were on EFV/FTC/TDF STR, and historically 57 were on r-PI and 14 were on NNRTI regimens. Participants were largely non-white (61%), male (73%) and had a high prevalence of lifetime injection drug use (63%). Forty-one percent were depressed, defined by a BDI-II score of > 13. Participants were also largely nucleoside experienced (65%) and had a median of 27.6 months of prior antiretroviral therapy. Most of the ritonavir-boosted PI-based regimens included either lopinavir-ritonavir (46%) or atazanavir-ritonavir (54%). NNRTI-treated individuals were on nevirapine (57%) or efavirenz (43%). The dosing frequency in the r-PI group was 47% once daily, 51% twice daily and 2% three times daily. The dosing frequency in the NNRTI was 36% once daily and 64% twice daily. There were no significant sociodemographic, prior treatment, or adherence differences between EFV/FTC/TDF STR, non-one-pill daily, r-PI-treated, and NNRTI groups (). There were significant differences in calendar year of HAART initiation among the regimen types. The median year of antiretroviral initiation was 2008 for EFV/FTC/TDF STR, 2006 for r-PI, and 2002.5 for NNRTI (p<0.0001, Savage Exactrank sum).
Participant Characteristics by Treatment Group.
The mean adherence to EFV/FTC/TDF STR was 86% (SD±18%). This was higher than the mean adherence to all non-one-pill daily regimens (73%, SD±0.23%, P=0.001), to all r-PI regimens (75%, SD±21%, P=0.006), and all NNRTI regimens (68%, SD±26%, P=0.02). The proportion achieving 90% adherence was higher (58%) in the EFV/FTC/TDF STR than in the combined non-one-pill (35% p=0.02) group, the r-PI (37%, p=0.035) group, but did not reach statistical significance in the NNRTI (29%, p=0.072) group in univariable analyses. Adherence was greater in the EFV/FTC/TDF STR group than the non-one-pill daily subgroup in a generalized estimating equation (GEE) analysis controlling for gender, race, high school education, income, homelessness, injection drug use, nadir CD4, BDI, prior antiretroviral use, and calendar year (, p=0.0060). Adherence was also greater in the EFV/FTC/TDF STR group than the r-PI subgroup GEE analysis controlling for the same confounders (p=0.004). Higher CD4 nadir was also associated with better adherence, which may suggest that individuals presenting early for care may be better able to adhere than those delaying presentation with advanced disease. There were insufficient individuals (n=14) for a similar multivariable NNRTI subgroup analysis.
Generalized estimating equation predictors of adherence: EFV/FTC/TDF STR vs. non-one pill, once daily regimens (NNRTI and rPI combined).
Viral suppression (defined as HIV RNA <50 copies/ml) was greater in the EFV/FTC/TDF STR (69%) group compared to either the non-one pill daily group (46%, p=0.02) or the r-PI (47%, p=0.034) group, but not in the NNRTI (43%, p=0.111) group. The high rates of viral suppression to NNRTI-based regimens at moderate adherence is consistent previous published results from this cohort[17
]. The difference between EFV/FTV/TDF STR and r-PI group was not significant when controlling for adherence, suggesting that this difference was more closely related to differences in adherence than differences in regimen potency.
Many individuals with less than perfect adherence to an NNRTI based regimen exhibited viral suppression. Among the individuals on EFV/FTC/TDF STR, the virologic suppression rates at month 6 were 50%, 50%, 33%, 67% and 83% for the adherence categories 0-49% 50-74%, 75-79%, 80-89%, and 90-100% respectively. Viral suppression in the r-PI group was 20%, 18%, 50%, 56%, and 71% in the same adherence categories.