Virological Failure and Drug Resistance in Patients on Antiretroviral Therapy After Treatment Interruption in Lilongwe, Malawi

Background. Since 2004, Malawi has rapidly scaled up access to antiretroviral therapy (ART) in the national program following a public health approach with limited laboratory monitoring. We examined virological outcomes in patients with treatment interruption at 2 clinics of the Lighthouse Trust, Lilongwe, Malawi. Methods. We evaluated patients who resumed first-line ART after having at least 1 treatment interruption documented in the electronic data system in 2008-2009. Viral load (VL) was analyzed at least 2 months after resumption of ART. For VL >= 1000 copies/mL, drug-resistance genotype was characterized using the Stanford database. Results. Between June and November 2009, we enrolled 133 patients (58.7% female) with a mean age of 38.4 years. Mean duration of ART prior to treatment interruption was 14.3 months. After a minimum of 2 months following ART resumption, VL was undetectable in 81 (60.9%) patients, was 400-1000 copies/mL in 12 (9.0%) patients, and was >= 1000 copies/mL in 40 (30.1%) patients. Genotyping and drug-resistance testing were successfully performed for 36 of 40 patients, all carrying human immunodeficiency virus type 1 subtype C. Relevant mutations affecting nonnucleoside reverse transcriptase inhibitors were found in 32 of 133 (24.1%) patients and combined with relevant nucleoside reverse transcriptase mutations in 27 of 133 (20.3%) patients. Conclusions. Virological failure combined with drug resistance after resumption of first-line ART occurred in 24.1% of the patients with treatment interruption, requiring a switch to protease inhibitor-based second-line therapy. Patients with treatment interruption should receive VL assessment after resumption of ART to detect treatment failure and to reduce development and spread of drug resistance.