The study aimed to identify the predictive factors associated with virological failure among adult patients living with HIV on first-line highly active antiretroviral therapy (HAART) in selected hospitals in Southeast Oromia, Ethiopia.

A facility-based unmatched case–control study was conducted.

The study was conducted in three selected hospitals in Southeast Oromia, Ethiopia.

The study included a final sample size of 282 participants, comprising 94 cases and 188 controls. A simple random sampling technique was employed to select participants.

The main outcome of this study was virological failure among adult patients living with HIV on first-line HAART. Virological failure was defined as a binary outcome: a case indicated the presence of failure, defined as adults aged≥15 years with a viral load (VL)>1000 copies/mm³ in two consecutive measurements taken 3 months apart, following enhanced adherence counselling (EAC) after 6 months of treatment. A control indicated the absence of failure, defined as patients aged≥15 years with a VL3 in two consecutive measurements after at least 6 months of treatment. The study used routine viral load testing records, recommended at 6 and 12 months and annually thereafter, with the WHO threshold of 1000 copies/mL used to define virological failure.

Individuals under the age of 35 had higher odds of virological failure (adjusted OR (AOR): 2.0; 95% CI (1.1 to 3.6)) compared with those older than 35. People with a body mass index (BMI) below 18.5 had higher odds of virological failure (AOR: 2.4; 95% CI (1.0 to 5.7)). Those with poor adherence had significantly higher odds of virological failure (AOR: 5.1; 95% CI (2.7 to 9.9)). Individuals attending less than 50% of their scheduled visits had increased odds of virological failure (AOR: 3.2; 95% CI (1.3 to 8.0)). Those with a history of co-trimoxazole preventive therapy use had higher odds of virological failure (AOR: 4.1; 95% CI (1.4 to 11.9)). Individuals with a baseline CD4 (cluster of differentiation) count below 200 cells/mm³ had higher odds of virological failure (AOR: 3.6; 95% CI (2.0 to 6.7)) compared with those with higher counts.

The study has identified several key factors, including education level, marital status, duration of HAART, younger age, current BMI, adherence to treatment, scheduled healthcare visits, history of co-trimoxazole preventive therapy use and baseline CD4 count, as significant determinants of virological failure within the studied population. The study’s identification of determinants of virological failure among people living with HIV is crucial for decreasing the prevalence of virological failure and improving the health of people living with HIV. Therefore, targeted counselling and support can play a crucial role in enhancing patient understanding, motivation and engagement with their treatment, ultimately contributing to improved virological suppression and overall health.