Background:  The introduction of generic ART in India dramatically reduced costs and improved access to therapy. However, numerous factors could affect the efficacy and durability of ART, including over-the-counter availability, out-of-pocket payment for medications, and use of alternative medications. We analyzed the prevalence of virologic failure and extent of drug resistance among HIV-1-infected, treatment-experienced patients in Chennai, India.

Methods:  This analysis was conducted at YR Gaitonde Centre for AIDS Research and Education (YRGCARE), which has provided medical care to over 9500 HIV-infected patients, >4000 of whom have been started on ART. In September 2005, YRGCARE performed viral-load testing on 95 consecutive patients who had been on ART for >1 year and who had not switched regimens due to suspected treatment failure in the prior 6 months. All samples with detectable viral load underwent genotypic resistance testing and the results were interpreted using the genotypic resistance interpretation program available at http://hivdb.stanford.edu. Demographic, clinical, and laboratory data were extracted from the hospital database or medical records. Multivariate logistic regression was performed using SPSS Version 13.0.

Results:  Mean age was 33 years; 68% were male. Mean duration of ART was 32 months. Prevalence of detectable viral load (>400 copies/mL) was 53.7% overall, and was 81.8% among those on therapy for >4 years. Multivariate analysis revealed that missed doses in the prior 3 days, low CD4 count at viral load quantification and use of nevirapine (NVP) as part of the initial regimen (p <0.05) were associated with a detectable viral load. Almost all (40 of 41 or 97.5%) patients on non-nucleoside reverse transcriptase inhibitor (NNRTI) -containing regimens and 82% (36 of 44) of patients on lamivudine (3TC) -containing regimens demonstrated high-level resistance to NNRTI and 3TC, respectively. The most common NNRTI mutations were K103N (44%), Y181C (25%), G190A (14%), and V106M (11%). M184V/I was detected in 82%. Intermediate or high level resistance to NRTI was as follows: thymidine analogs (18%), tenofovir DF (4.5%), abacavir (20.5%), didanosine (25%).

Conclusions:  Virologic failure was common among ART-treated patients in Chennai and was associated with drug resistance. Viral Load monitoring should be used routinely to detect early treatment failure and minimize drug resistance. Measures to improve adherence and provide uninterrupted access to HAART may reduce treatment failure rates and preserve future treatment options.