The virological response to highly active antiretroviral therapy over the first 24 weeks of therapy according to the pre-therapy viral load and the weeks 4-8 viral load

Objectives: To describe the viral response to HAART by weeks 4 and 8 in pre viously antiretroviral-naive patients. To assess whether the weeks 4 or 8 v iral loads are useful predictors of viral suppression by week 24. Design: A large clinical database including 453 antiretroviral-naive patien ts whose plasma viral load was monitored every 4 weeks. Methods: Observed probabilities of achieving a viral load less than or equa l to 500 copies/ml by week 24 (days 84-168) from starting highly active ant iretroviral therapy (HAART) were calculated according to viral loads at wee ks 4 and 8. Results: A total of 42.4% of patients (153/361) reached less than or equal to 500 copies/ml viral load by week 4 and 70.4% (245/348) by week 8. Viral suppression below 500 copies/ml by 4-8 weeks was similar irrespective of th e pre-HAART viral load. In patients with viral loads above 10 000 copies/ml at week 4, 60.6% (20/33) achieved less than or equal to 500 copies/ml by w eek 24. In patients with viral toads still above 10 000 copies/ml at week 8 , only 42.3% (11/26) achieved less than or equal to 500 copies/ml by week 2 4, and only 33.3% (3/9) maintained viral suppression below 500 copies/ml to week 48. Conclusion: Viral loads at weeks 4 and 8 should be monitored to detect earl y signs of low subsequent viral suppression. For previously antiretroviral- naive patients whose viral loads after 8 weeks of HAART are still above 10 000, there is an urgent need to assess adherence to therapy, drug levels an d resistance, so management can be modified accordingly to reduce the rate of week 24 virological failure. (C) 2001 Lippincott Williams & Wilkins.