Impact of early versus late adherence to highly active antiretroviral therapy on immuno-virological response: a 3-year follow-up study.

Objective: To assess the impact of different patterns of adherence to highly active antiretroviral therapy (HAART), in particular, the relative impact of early and late adherence, on long-term immuno-virological response in HIV-infected individuals started on a protease inhibitor-containing regimen.

Design: Clinical, immuno-virological and self-reported adherence data were collected at 4 (M4), 12 (M12), 20 (M20), 28 (M28) and 36 (M36) months after HAART initiation in the French APROCO cohort.

Methods: A standardized self-administered questionnaire classified patients as non-adherent, moderately or highly adherent at each visit. Stable viral suppression at both M28 to M36, and a CD4 cell increase > 200 between M0 and M36 were used as outcome measures.

Results: Of the 582 patients followed regularly through M36, 360 patients had complete adherence data. Although 59.2% were highly adherent at M4, only 25.8% maintained consistent high adherence throughout the follow-up. High adherence at M4 was independently associated with both stable viral suppression at M28-M36 [OR (95% CI): 2.8 (1.4-5.5)] and a CD4 cell increase > 200 during the same period [OR (95% CI): 3.9 (1.7-9.7)]. However, 'moderately adherent' patients between M12 and M36 had the same likelihood [OR (95% CI): 1.9 (1.1-3.2)] as patients who were always high adherent [OR (95% CI): 1.9 (1.1-3.2)] of achieving stable viral load suppression, relative to those who reported non-adherence episodes.

Conclusion: Optimizing adherence in the early months of treatment is crucial to ensure long-term immuno-virological high adherence during follow-up have a less negative impact. Priority should be given to interventions aimed to improve adherence in the early months of HAART.