Immunologic, virologic, and clinical consequences of episodes of transient viremia during suppressive combination antiretroviral therapy.

OBJECTIVE: To investigate immunologic, virologic, and clinical consequences of episodes of transient viremia in patients with sustained virologic suppression.
METHODS: From the AIDS Therapy Evaluation Project, Netherlands cohort, 4447 previously therapy-naive patients were selected who were on continuous combination antiretroviral therapy and had initial success (2 consecutive HIV RNA measurements <50 copies/mL). During episodes of viral suppression (RNA <50 copies/mL), low-level viremia (RNA 50 to 1000 copies/mL), or high-level viremia (RNA >1000 copies/mL) after initial success, the occurrence of therapy changes, drug resistance, and clinical events was assessed.
RESULTS: During 11,187 person-years of follow-up, 1281 (28.8%) patients had at least 1 RNA measurement >50 copies/mL. Among 8069 episodes, there were 5989 (74.2%) episodes of suppression, 1711 (21.2%) episodes of low-level viremia, and 369 (4.6%) episodes of high-level viremia. Most episodes of low-level viremia consisted of < or =2 RNA measurements (93.7%), were without clinical events or therapy changes (79.6%), and were without changes in CD4 cell counts. Therapy changes (52.3% of episodes) and resistance (23.3%) were frequently observed during high-level viremia.
CONCLUSIONS: Episodes of low-level viremia are frequent and short lasting, and the low proportion of episodes with clinical events suggests that leaving therapy unchanged is a clinically acceptable strategy. In contrast, high-level viremia is associated with resistance and is often followed by therapy changes.