Modeling HIV infectivity: must sex acts be counted?
Article Abstract:
The extent of the acquired immunodeficiency syndrome (AIDS) epidemic depends on the transmission of the human immunodeficiency virus (HIV), which causes AIDS. The probability that a noninfected person will become infected after exposure to HIV has been assessed using statistical models. These models of HIV infectivity are essential for evaluating the course of the AIDS epidemic, developing alternative AIDS intervention policies, and educating the general public. In some models of HIV infectivity, the probability of HIV infection is constant and related to each sex act or to the course of a relationship between an uninfected person and an infected one. Other models suggest that the probability of HIV infection is not constant, but varies with the number of infected individuals or duration of relationship with an infected individual. The usefulness of these models of infectivity in estimating the probability of HIV infection was assessed using two groups of data. One set of data involved HIV transmission from men to women with repeated vaginal sex acts with the same infected partner. The other set of data involved HIV transmission among men practicing anal intercourse with several different sex partners. The results suggest that although models of HIV infectivity should account for number of sexual partners, the probability of HIV infection may not necessarily be related to number of sex acts. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Journal of Acquired Immune Deficiency Syndromes
Subject: Health
ISSN: 0894-9255
Year: 1990
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Modeling zidovudine therapy: a cost-effectiveness analysis
Article Abstract:
Zidovudine (ZDV) is the first drug that has been approved by the Food and Drug Administration for the treatment of HIV (human immunodeficiency virus) infection and AIDS. ZDV slows the progression of HIV to the disease state known as AIDS and prolongs the lives of infected individuals. However, with a longer life expectancy, those who are infected with HIV have a greater chance of spreading the virus to others. The overall economic costs to society are also thought to be increased as a result of ZDV treatment. A mathematical model is presented analyzing ZDV therapy and HIV transmission in a population of infected gay men, who did not have any symptoms of disease. The model showed that with treatment there were no significant increases in the number of AIDS patients or in the overall costs of AIDS. The model also showed that ZDV prolongs the incubation time of the virus before full-blown infection develops and reduces the incidence (number of new cases) of AIDS in the long-term. The authors concluded that ZDV is a cost-effective therapy, especially when behavioral changes and prevention techniques are practiced by those who are being treated. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Journal of Acquired Immune Deficiency Syndromes
Subject: Health
ISSN: 0894-9255
Year: 1991
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The epidemiological and economic consequences of AIDS clinical trials
Article Abstract:
A decision-making model incorporating epidemiological, economic and statistical factors of AIDS research into one system for drug evaluation and policy implementation is presented. The analysis is based on a compartmental model, which divides a population into groups sharing the same demographic or epidemiological characteristics, and on a decision-making tree. Then, inputting what is known about the population and the disease - means of transmission, cost of therapy, adverse side effects, behavioral aspects - the model can be used to evaluate such things as when to initiate or abandon a clinical trial or how long one should run. The model also accounts for such things as the hidden costs of delaying drug approval, the effects of taking no action and the value of information. While the model simplifies certain factors and makes some unrealistic assumptions, it highlights the importance of a coordinated approach to balancing the risks of premature release of unsafe drugs with the costs of postponing approval.
Publication Name: Journal of Acquired Immune Deficiency Syndromes
Subject: Health
ISSN: 0894-9255
Year: 1993
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