HIV drug resistance in newly infected and treatment-naïve patients in France did not rise in 2001-2 compared with previous years, in contrast to recent increases amongst these patient groups in the United Kingdom. The findings come from a review of two French cohorts published in the April 15th edition of the Journal of Acquired Immune Deficiency Syndromes.
Wide variations in the prevalence of drug-resistant HIV in newly infected and treatment-naïve individuals have been reported in Europe, together with differences in the rates of change in prevalence over time.
In the United Kingdom the prevalence of drug-resistant HIV in newly infected gay men rose from 20% in 2001 to 27% in 2002, according to data from the Health Protection Agency presented at the Fifteenth International AIDS Conference in Bangkok last year.
A pan-European analysis of 2208 seroconverters presented in 2003 found evidence of drug resistance in 10.5% of patients.
These contradictory patterns have led experts to argue that it is impossible to make international recommendations about optimal regimens for post-exposure prophylaxis and first-line treatment, and that more detailed information is needed on the prevalence of drug resistance in particular populations and countries.
The French study
French researchers used data from two cohorts in their analysis: 303 patients with acute HIV infection (the Primo study) and 363 treatment-naïve patients infected with HIV for a median of six months (the Odyssee study).
Using the International AIDS Society-USA Resistance Testing Panel list of mutations, the researchers looked at the prevalence of reverse transcriptase and protease mutations in the Primo cohort. Overall, 14% of patients had resistance mutations. Ten per cent had resistance to nucleoside analogues (NRTIs), 3.3% to NNRTIs and 4.3% to protease inhibitors. In the Odyssee cohort the overall prevalence was 6% (4.3% to NRTIs, 0.8% to NNRTIs and 1% to PIs).
Using the French ANRS guidelines for defining drug resistance, 12% of patients in the Primo cohort had drug resistance, whilst 1.7% of the Odyssee cohort had drug resistance.
The frequency of drug resistance did not change between 1996 and 2001 in acutely infected patients, and fell slightly in chronicaly infected patients. The authors suggest that this trend reflects the fall in the proportion of French patients capable of transmittting drug resistant virus (those with detectable viral load) from 48% in 1999 to 31% in 2002.
The magnitude of difference between acutely infected and chronically infected patients in this study is likely explained by the dwindling of drug resistant sub-populations over time in chronically infected individuals, rather than a sudden acceleration in the rate of transmission of drug-resistant virus in France.
However, the study did find an increase in the proportion of patients infected with non-B HIV subtypes. Seventeen per cent of patients of European origin were infected with a non-B subtype in 2002 compared to 14% in 1999.
Descamps D, Chaix ML, et al. French national sentinel survey of antiretroviral drug resistance in patients with HIV-1 primary infection and in antiretroviral-naïve chronically infected patients in 2001-2002. J Acquir Immune Defic Syndr 38 (5): 545-552, 2005.
Rinck G et al. Trends in transmitted antiretroviral drug resistance in men who have sex with men attending genitourinary medicine clinics in England, Wales and Northern Ireland. XV International AIDS Conference, Bangkok, abstract PpC4713, 2004.
Wensing A et al. Drug susceptibility patterns in 195 European patients de novo infected with drug-resistant virus: implications for post-exposure prophylaxis. Ninth European AIDS Conference, Warsaw, abstract LBF6/1, 2003.