Eighth International Congress on Drug Therapy in HIV Infection Glasgow, UK - 12-16 November 2006

Int Cong Drug Therapy HIV 2006 Nov 12-16;8:Abstract No. PL5.5

J Vercauteren, K Theys, M Debruyne, A P Carvalho, A M Vandamme, R Camacho
Rega Institute, KULeuven, Belgium

PURPOSE OF THE STUDY: Current HAART regimens are increasingly efficient. Yet, multidrug-resistance (MDR) is reported to increase. Such reports describe cumulative prevalences over time, though this does not reflect trends on acquiring resistance. To evaluate whether MDR is related mainly to inefficient treatments in the past, or whether MDR is still increasing with current regimens, we examined the incidence of MDR.

METHODS: From the Portuguese Resistance Database, we selected all 2192 drug-experienced patients with at least one genotype performed between July 2001 and March 2006, a period during which implementation of routine resistance testing for treatment failure was constant. 2726 sequences were interpreted using Rega 6.4.1. MDR was defined as harboring a virus which is estimated to be susceptible to at most 1 drug, reflecting the inability to install efficient treatment. Incidences were calculated using a single genotype per patient per year. The trend was investigated by the Chi-square test for proportions and by Poisson regression. We corrected for confounding factors using multivariate logistic regression.

SUMMARY OF RESULTS: From 2001 to 2006, we noticed a significant trend of MDR with 5.7% [4.0-8.0] in 2001-‘02, 5.7% [4.0-8.0] in 2002-‘03, 4.5% [2.9-6.5] in 2003-‘04, 3.4% [2.1-5.1] in 2004-‘05, 3.3% [1.4-6.3] in 2005-‘06 (P=0.016). Poisson regression confirmed the significant decrease of MDR incidence (P=0.019). The model predicted that from 2001 to 2006 the incidence decreased relatively with on average 16% [3-27]. After correcting for time on therapy, multivariate logistic regression validated the decrease of MDR over time (OR 0.82, [0.70-0.96]; P=0.013).

CONCLUSIONS: The incidence of MDR is decreasing over time in Portugal, reflecting the increasing efficiency of HAART. We anticipate that, in a near future, activity against resistant viruses will not be the primary target for the design of new drugs. Better tolerability, ease of use or less toxicity may instead be favored.

Plenary Session: Oral Papers

2006-11-12
PL5.5

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