AEGiS-Glasgow [PL5.3] Epidemiology of antiretroviral resistance

Seventh International Congress on Drug Therapy in HIV Infection

Glasgow, UK - 14-17 November 2004

[PL5.3] Epidemiology of antiretroviral resistance

Int Cong Drug Therapy HIV 2004 Nov 14-18;7:Abstract No. PL5.3

Deenan Pillay
Department of Virology, University College London, London, UK

Emergence of HIV drug resistance is well recognised and important in determining subsequent drug response. It also has a number of implications at a population level. Continuing exposure to antiretroviral drugs may increase the proportion of patients ultimately requiring new classes of drug, particularly when considering the persistence of resistant strains over time as archived viruses. The ongoing epidemic in many communities also allows such resistant viruses to be transmitted, which is associated with reduced response to first line therapy. Therefore, deriving estimates of the prevalence of resistance in treated and untreated individuals is important. However, this is fraught with methodological problems. For instance, deriving a prevalence of resistance in treated patients requires consideration of archived resistance, and also the placing of prevalence data within the context of the total treated population. Thus, whereas UK national data suggest ~75% of resistance tests undertaken on treated patients demonstrate any level of resistance, this figure falls to 15% of all treated patients, when adjusting the denominator. With regard to estimating transmitted resistance, a further problem is in the definition of such viruses, since mutations signifying resistance in a treated individual may not reflect transmitted resistance when present alone. This may explain the wide variation (5-25%) of estimates in studies to date.

Unfortunately, existing datasets vary significantly in the types of population surveyed, and definitions of resistance, making it difficult to draw clear conclusions on these issues. It is essential to identify the precise purpose for estimating for epidemiological analysis before implementing optimal methological approaches.

SESSION 5: ADHERENCE, RESISTANCE, CLINICAL PHARMACOLOGY AND DISEASE MONITORING

2004-11-14
PL5.3

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