Antiretroviral drug resistance testing in patients with HIV-1 infection: a meta-analysis study

HIV-1 resistance tests, both phenotype and genotype, have been entering clinical practice during the last years, but limited prospective studies have been reported in antiretroviral-treated patients with virological failure.

A meta-analysis of randomized controlled trials (RCTs) published or presented at the most important international conferences until February 2001 was performed to estimate the impact of resistance-guided antiretroviral therapy on virological outcome.

A search for RCTs was performed by using a MEDLINE database, Internet sources, and international conference presentations and was updated September 2001. All RCTs available, including four RCTs on genotype resistance testing, one RCT on phenotype resistance testing, and one RCT on genotypic and phenotypic testing, were analyzed. The rate of patients with undetectable viremia at 3 months was reported in all RCTs and the rate at 6 months was reported in 4 of 6 RCTs.

The rate of patients with undetectable viral load after 3 months was 42.6% in patients who were treated based on genotype results and was 33.2% in patients who were treated based on standard of care (SOC; odds ratio [OR] 1.7; 95% CI: 1.3-2.2). At 6 months, undetectable viremia was observed in 38.8% and 28.7% of the patients, respectively (OR: 1.6; 95% CI: 1.2-2.2). In 142 patients, expert advice was provided to optimize clinical use of genotypic data. The higher rate of viral suppression was achieved in this subgroup of patients (50.7% vs. SOC 35.8%; OR 2.4; 95% CI 1.5-3.7). In contrast, undetectable viremia was achieved in 37.5% patients who were treated based on phenotype results versus 33.8% patients who were treated based on SOC (OR 1.1; 95% CI 0.8-1.6).

These results support the use of a genotypic test in patients experiencing virological failure during antiretroviral treatment. Expert interpretation of the test may increase the probability of virological response.