PrEP no panacea

One potential approach to HIV prevention attracting much current interest is the use of “pre-exposure prophylaxis” (PrEP). This involves taking anti-retroviral drugs (ARV) before exposure to HIV in order to reduce the risk of transmission. In parallel with clinical trials currently underway to establish the efficacy of PrEP, an important body of research is investigating its acceptability for potential users. A recent study of PrEP acceptability among “at risk” populations in Lima, Peru (female sexual workers (FSM); men who have sex with men (MSM); male-to-female transgendered persons (TG)) complements on-going clinical trials of Truvada as PrEP in the city. It also claims to be the first PrEP acceptability study undertaken outside the US.
The study recruited 45 participants, and involved the generation of material for analysis through focus groups, as well as “conjoint analysis”. The latter technique, more familiar in the context of marketing research, confronts participants with a number of hypothetical products (8 in this study) composed of various combinations of pre-determined attributes. So, the “products” of this analysis were distinguished on the basis of the attribute of “cost” as expensive ($250) or cheap ($10); on the basis of the attribute of efficacity as more efficacious (95%) or less ($70) – and so forth for 7 pre-determined key attributes. Participants were invited to score 8 products, and subsequent analysis allows us to establish the impact of attributes on acceptability.
It is no surprise that cost, efficacy, and the presence/absence of side-effects (in that order) prove to be the most important attributes. The interest of this study may lie elsewhere. First there is the issue of potential up-take. While the highest acceptability score of 83% suggests the potential given the optimal drug, the authors suggest that the average acceptability of 53% may provide a more realistic indication of the likely take-up of any real-life product. In other words, PrEP does not look like a panacea – if we were tempted to expect one. Secondly, findings of the study point to the potential importance of sensitivity to target groups and micro-environments in the roll-out any PrEP intervention. For example, the reactions of participants tend to reveal marked disparities between the FSW participants and the MSM/TG participants in their view of the feasibility of “daily dosing”, or of the likelihood of increased risk-taking behaviour as a direct result of PrEP. There are also indications that very local environmental factors can impact on user preferences, e.g. the prevalence of small family-operated drugstores in Lima on the preference for PrEP being dispensed by health-care professionals rather than pharmacists.

J.T. Galea et al., “Acceptability of pre-exposure prophylasis as an HIV prevention strategy: barriers and facilitators to pre-exposure prophylaxis uptake among at-risk Peruvian populations”, International Journal of STD & AIDS 2011: 22: 256-262

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