12th Annual Conference of the British HIV Association 29 March–1 April 2006, Brighton, UK

THE REPRODUCIBILITY AND CLINICAL SIGNIFICANCE OF HIV VIRAL-LOAD BLIPS IN PATIENTS ON STABLE FIRST-LINE HAART

HIV Med 2006; 7(Suppl. 1):2 (abstract no. O6)

Gaia Nebbia, Clare Booth, Colette Smith, Ana Garcia-Diaz, Andrew Phillips, Margaret Johnson and Anna Maria Geretti
Royal Free and University College Medical School, London, UK

AIMS: Assess frequency, reproducibility and long-term impact of viral-load (VL) blips, and determine whether blips are associated with emergence of resistance.

METHODS: Reproducibility: two plasma aliquots were stored at 70°C. The second was tested under identical conditions if the first showed a blip (>50 and <400 copies/ml, preceded and followed by <50). Genotyping was done in six confirmed blips. In patients on first-line HAART with ≥2NRTIs + PI/NNRTI (n=486), univariable analysis was used to investigate whether having a blip was associated with subsequent VL rebound and CD4 changes over ≤5 years.

RESULTS: Among patients on first-line HAART (n=486), 367 (76%) were suppressers and 119 (24%) blippers during the first year after initial VL <50 copies/ml. Of the blippers, 35 (30%) had multiple blips (2–4). Over 938 PY of follow-up, the VL rebound rate per 100 PY was 3.36 (2.02–4.71) in suppressers (RR 1.25; CI: 0.51–3.07, P=0.62) versus 2.70 (0.16–5.83) in blippers. The rate of mean CD4 increase per month in suppressers was 1.35 cells/µl greater than in blippers (95% CI: (1.35 to 4.05; P=0.32). In 32 retested blips VL was >50 copies/ml in 11 (34%); detectable at <50 (10– 42) copies/ml in 13 (41%); and undetectable in eight (25%). Genotyping showed wild-type virus in four blips, including two on first-line HAART and two from multi-drug experienced patients with previously documented resistance. The other two blips showed resistant virus; in both, the resistance profile was consistent with selection during previous therapy.

CONCLUSIONS: Blips occurred in 24% of patients on stable first-line HAART, but did not impact on long-term virological and CD4 responses. On repeat testing, 75% of blips showed detectable viraemia. Blips contained either wildtype or drug-resistant virus, but resistant mutants appeared to derive from previous drug failures.

2006-03-29
O6

Copyright © 2006 - British HIV Association (BHIVA) Reproduction of this abstract (other than one copy for personal reference) must be cleared through the BHIVA Organising Secretariat 1 Mountview Court, 310 Friern Barnet Lane, London N20 0LD