Objective: To assess the occurrence of viral load greater than 50 copies/ml in patients on highly active antiretroviral therapy (HAART) having achieved less than 50 copies/ml and the chance of whether a viral load greater than 50 copies/ml would lead to a sustained and increasing viral load.
Design: A cohort of 553 patients on HAART with viral loads of less than 50 copies/ml were followed.
Results: Over a median of 56 weeks 35% of patients experienced a transient increase and 8% virological failure (two consecutive viral loads of > 400 copies/ml). Transient increases and virological failure were more common in those with greater drug experience, and those with initial raised viral load values of more than 400 copies/ml were more likely to have a sustained increase and become virological failures.
Conclusion: Transient increases in viral load are common, mainly in the 50-400 copies/ml range, and the majority of subsequent viral load estimations show a return to less than 50 copies/ml. A single raised viral load should lead to adherence support and intensified monitoring. Subsequent treatment decisions can then be based on evidence of true virological rebound and failure.