Criteria for initiation of highly active antiretroviral treatments (HAART) in HIV-infected patients remain a matter of debate world-wide because short-term benefits have to be balanced with costs of these therapies, and restrictions placed on future treatment options if resistant viral strains develop. In order to take into account irreversibility and inertia effects associated with ex ante choices, we propose a simple stochastic dynamic model of sequential therapeutic choice with intermediary revelation of information, in which the efficiency gains from a new effective Therapy in second period are conditional on the results of the treatment in the previous period. We find that identical patients may be administered different treatments at the optimum; for parameters implying an all or nothing cut decision in period 2, a more forward looking decision rule is required in period 1 because there will be little space for adjustment to its consequences. Another finding is that as soon as risks of resistance due to therapeutic failure of initial treatments are significant, as perhaps in developing countries and in marginalized groups of developed countries, differences in the estimation of this risk should not influence the optimal decision about the size of the HIV-infected population eligible for early antiretroviral Therapy. The decision should then be based on pure efficiency/cost considerations.
Le bien-fondé d'administrer précocement des traitements antirétroviraux à haute activité (HAART) aux personnes infectées par le VIH reste l'objet de débats dans le monde car leurs bienfaits à court terme peuvent compromettre les traitements futurs si des souches résistantes du virus se développent. Nous formulons un modèle qui combine irréversibilité et inertie dans un cadre de décision thérapeutique séquentielle. L'information se révèle entre la première et la deuxième période, si bien que la décision thérapeutique de deuxième période est conditionnelle à cette information. Il s'avère que des patients identiques peuvent se voir administrer des traitements différents à l'optimum; de plus, pour des paramètres justifiant des décisions bien tranchées en période 2 (à patients identiques traitement identique), la décision de période 1 est plus complexe car il est alors trop tard pour en renverser les conséquences en période 2. Autre résultat: supposons que le risque de résistance est élevé en cas d'échec thérapeutique du traitement initial (pays en développement; groupes défavorisés); nous montrons alors que les différences dans l'estimation de ce risque n'interviennent pas dans le choix optimal de la taille de la population qui se voit administrer le traitement antirétroviral. L'introduction du traitement relève alors purement de considérations d'efficacité et de coût.
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Find related papers by JEL classification: I18 - Health, Education, and Welfare - - Health - - - Government Policy; Regulation; Public Health C61 - Mathematical and Quantitative Methods - - Mathematical Methods and Programming - - - Optimization Techniques; Programming Models; Dynamic Analysis
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Geoffard, Pierre-Yves & Philipson, Tomas, 1996.
"Rational Epidemics and Their Public Control,"
International Economic Review,
Department of Economics, University of Pennsylvania and Osaka University Institute of Social and Economic Research Association, vol. 37(3), pages 603-24, August.
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