14th Annual Conference of the British HIV Association 23–25 April 2008, Belfast

EFFECT OF HIV-1 SUBTYPE ON VIROLOGICAL AND IMMUNOLOGICAL RESPONSES TO FIRST-LINE HAART

HIV Med 2008 Apr 23-25 (Suppl 1);14:3 (abstract no. O10)

L Harrison¹, AM Geretti², H Green¹, D Dunn¹ and E Fearnhill¹
1MRC Clinical Trials Unit, London, UK, 2Royal Free NHS Trust, London, UK

BACKGROUND: Few studies have analysed responses to HAART according to the HIV-1 subtype and most have simply compared B to non-B.

METHODS: Nai¨ve patients from the UK HIV Drug Resistance Database (linked to UK CHIC and other hospital databases) who started HAART, were >16 yrs, and had a baseline resistance test, viral load (VL) and CD4, and >12 months follow-up were included. Time to VL <50 copies/mL and time to VL rebound (2 consecutive VLs >1000 or 1 VL >1000 copies/mL followed by a treatment change) were analysed. CD4 responses were studied using repeated measures analysis. Multivariate analyses were adjusted for initial age, clinical centre, calendar year, HAART regimen, VL and CD4, plus time to VL <50 in the rebound analysis. Accurate adjustment for ethnicity or risk group could not be done due to their strong association with subtype.

RESULTS: Of 1400 patients, 1076 (77%) were subtype B, 151 (11%) C, 43 (3%) A, 35 (3%) CRF_AG, 28 (2%) D and 67 (5%) other subtypes. Overall, 1271 (91%) achieved a VL <50 within 12 months of starting HAART, of whom 256 (20%) subsequently rebounded. There was an association between subtype and time to VL <50 (P=0.02). More rapid suppression was observed for subtypes A (HR 1.62 (1.18,1.22), P=0.003) and C (HR 1.21 (1.01,1.44), P=0.04), compared with B. There was no evidence for a subtype effect on rebound (P=0.66). There were no differences in CD4 responses between subtypes at 3 months after HAART initiation (P=0.47) or subsequently (P=0.68).

CONCLUSIONS: Persons infected with prevalent non-B subtypes in the UK show excellent and durable responses to first-line HAART. Subtypes A and C respond more rapidly than B. Further studies are needed to explore the influence of ethnicity, risk group and adherence.

2008-04-23
O10

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