Background and objectives: Human Immunodeficiency Virus (HIV), a Lentivirus (a subgroup of retrovirus), infects humans and causes progressive failure of the immune system that ultimately leads to AIDS (acquired immunodeficiency syndrome), a state which allows life-threatening opportunistic infections and cancers to thrive. Despite the reduction in mortality and morbidity with the introduction of highly active antiretroviral therapy (HAART), a considerable proportion of patients fail to achieve a sustained virologic response to therapy, which has led to treatment failure. National AIDS Control Organisation (NACO) has developed simple immunological, virological and clinical criteria to diagnose treatment failure. The study aimed to determine the correlation between patients with immunological failure and virological failure in a study group of people living with HIV/AIDS (PLHA) on 1st line anti-retroviral therapy (ART) after six months of treatment. Methods: A hospital-based observational study was done with data collected over one year. The study included patients above 15 years of age with treatment failure (either immunological or clinical, as defined by NACO) after six months of ART. As per definition of NACO, virological failure was defined as a plasma viral load (PVL) of >1000 copies/ml. Results: Out of 90 patients with an immunological failure, only 74 patients also had virological failure, resulting in a 17.78% discordant response. Discordance between immunological failure and virological failure was more common in patients with a low baseline CD4 count and patients on a Zidovudine-based regimen. Moreover, adherence to therapy played an essential role in the development of treatment failure.

Conclusion: Instead of targeted viral load testing, universal access to routine viral load testing is necessary for the early diagnosis of treatment failure with a switch to 2nd line ART and to avoid immuno-virological discordance. Adherence was observed to be an essential predictor of ART effectiveness.

Keywords: Treatment failure; Zidovudine; CD4 count; plasma viral load; adherence