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Session 95 Poster Abstracts
Transmission of Drug Resistant HIV-1: Conflicting Trends and Clinical Significance
Monday, 1:30 - 3:30 pm
Poster Hall


685
The Effect of Transmitted Drug Resistance on Virological Response to HAART Regimens Adjusted for Genotypic Resistance at Baseline
D Pillay*1, S Jurriaans2, M Prins3, B Masquelier4, F Dabis5, C Nielsen6, C Pedersen7, C de Mendoza8, J Belda9, C Balotta10, G Rezza11, R Gifford1, K Porter12, and CASCADE Virology Collaboration
1Univ. Coll. London, UK; 2Academic Med. Ctr., Amsterdam, The Netherlands; 3GGGD, Amsterdam, the Netherlands; 4Hosp. Pellegrin, Bordeaux, France; 5ISPED, Bordeaux, France; 6SSI, Copenhagen, Denmark; 7Odense Univ. Hosp., Denmark; 8ISC III, Madrid, Spain; 9IVESP, Valencia, Spain; 10IITD, Milan, Italy; 11ISS, Rome, Italy; and 12MRC CTU, London, UK

Background:  Although virological response is slower for persons with transmitted drug resistance to the treatment used in their HAART regimen, little information is available on response to HAART regimens which exclude treatment to which the patient may be resistant. We examined the effect of transmitted drug resistance on time to viral load suppression for seroconverters adjusting for the number of active drugs in their HAART regimen.

Methods:  We examined data from HIV-infected persons genotyped prospectively and retrospectively within 18 months of an HIV-antibody-negative test while naïve to therapy, from 6 seroconverter cohorts in Europe.  Using Kaplan-Meier methods we examined the effect of transmitted drug resistance on time to HIV RNA <500 copies/mL following initiation of HAART adjusting for: year of seroconversion; sex, exposure category, age at seroconversion; previous ART; time from seroconversion to HAART; and number of active drugs in HAART regimen.

Results:  Of 152 persons initiating HAART, 20 (13%) had one or more key mutations at seroconversion conferring resistance to therapy; 132 (87%) persons reached HIV RNA <500 copies/mL at a median of 97 days (95% CI = 78 to 117) following HAART.  We found no evidence to suggest that transmitted drug resistance was associated with different time to viral suppression once we adjusted for individuals without a fully active HAART regimen (i.e. number of active drugs less than number of drugs in regimen); HR = 1.18, 0.43 to  3.26, p = 0.7.  We further examined the possible effect of resistance to NRTI, NNRTI, or PI drugs and found no evidence to suggest that transmitted resistance to any one class conferred a disadvantage in terms of virological response (p = 0.4, 0.2, and 0.3, respectively).

Conclusions:  Early response to HAART was not compromised by transmitted drug resistance, adjusting for time between seroconversion and initiation of therapy, and the number of active drugs used. However, long-term follow-up is essential to assess the impact of durability if viral suppression and response to subsequent regimens.

Keywords: transmitted resistance; seroconverters; virological response