Effect of immediate initiation of antiretroviral treatment on the risk of acquired HIV drug resistance.   AIDS
Lodi et al. on behalf of the HIV-CAUSAL collaboration aimed to estimate and to compare the 7-year risks of acquired drug resistance under immediate antiretroviral therapy (ART) initiation and the previously recommended CD4+ cell count-based initiation strategies. The authors defined acquired drug resistance using the Stanford classification as resistance to any antiretroviral drug that was clinically identified at least 6 months after ART initiation.
In 50’981 eligible individuals, 10% had CD4+ cell count more than 500 cells/ml at baseline, and 63% initiated ART during follow-up. Of 2’672 tests for acquired drug resistance, 794 (30%) found resistance. The estimated 7-year risk of acquired drug resistance was 3.2% for immediate initiation, 3.1% for initiation with CD4 + cell count less than 500 cells/ml, and 2.8% for initiation with CD4+ cell count less than 350 cells/ml. In analyses restricted to individuals with baseline in 2005–2015, the corresponding estimates were 1.9%, 1.9%, and 1.8%.
In conclusion, the study-results show that the risk of acquired drug resistance was similar under immediate and delayed ART initiation. Compared with ART initiation with CD4+ less than 500 cells/ml or AIDS and CD4+ less than 350 cells/ml or AIDS, immediate ART initiation increased the 7-year risk of acquired drug resistance by only 0.13 and 0.37%, respectively. The estimated 7-year risk of clinically identified acquired drug resistance was approximately 3% under all ART initiation strategies. These risks and risk differences were even lower in individuals with initial CD4+ cell count more than 500 cells/ml and individuals who entered the study after 2004.