Seventh International Congress on Drug Therapy in HIV Infection Glasgow, UK - 14-17 November 2004

Int Cong Drug Therapy HIV 2004 Nov 14-18;7:Abstract No. PL6.1

A. Phillips, D. Dunn, C. Sabin, A. Pozniak, R. Matthias, A. Geretti, J. Clarke, D. Churchill, I. Williams, T. Hill, H. Green, K. Porter, G. Scullard, M. Johnson, P. Easterbrook, R. Gilson, M. Fisher, C. Loveday, B. Gazzard, D. Pillay
UK Resistance Database, UK CHIC Study, London/Brighton, UK

To describe the long term risk of development of drug resistance for patients starting with three or four drug antiretroviral therapy (ART) in routine clinical practice.

Information was assembled on resistance tests performed as part of routine care on patients from six large HIV clinics around London. Patients were therapy naïve before starting ART with two nucleosides plus either a single protease inhibitor (PI), a PI with ritonavir, abacavir or a non-nucleoside reverse transcriptase inhibitor (NNRTI).

4306 patients were followed; 1436 (33%) started with a single PI, 279 (6%) with a PI plus ritonavir , 156 (4%) with triple nucleosides and 2435 (57%) with an NNRTI. The overall cumulative risk of viral load failure was 38% by 6 years. Risk of ≥1 major IAS USA mutation was 27% by 6 years; risk of mutations from at least two of the three main drug classes was 20% over the same period. These are lower limit estimates as test results were not available for many with viral load failure, and resistance below sensitivity limits of assays will be missed. In an analysis of patients starting ART in or after 1998, risk of PI mutations being detected in people who started regimens containing a PI with ritonavir was significantly lower than the risk of NNRTI mutations being detected in those starting with an NNRTI regimen (relative hazard 0.31 95% CI 0.15-0.61; p=0.0008).

In routine practice, rates of viral load failure and of resistance detection in patients who started ART with three or four drugs are appreciable.

SESSION 6: RESISTANCE AND PHARMACOKINETICS

2004-11-14
PL6.1

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