Biomedical subjects

A B Mariotto

Publications and source records attributed to A B Mariotto.

4 recordsLinked to original sources

PubMed2000

Using AIDS mortality data to reconstruct HIV/AIDS epidemics.

The back-calculation methods used to reconstruct HIV epidemics and to predict future AIDS cases use data on the number of AIDS reported cases and information about the time from HIV infection to AIDS diagnosis. In this paper we modify a back-calculation method, presented in Verdecchia and Mariotto, to estimate HIV incidence from AIDS mortality data rather than the AIDS registered cases. In this application the AIDS incubation time is replaced by the time from HIV infection to AIDS death. Since AIDS is an irreversible condition leading to death within a few years, mortality data is expected to be approximately as informative as AIDS data. The main application of this method would be in countries where an AIDS registry is not available or where the registration of AIDS cases is not consistent, for example, due to changes in the definition of AIDS. Application to the Italian AIDS mortality data shows that the number of AIDS cases reconstructed from this method is very close to the registered number of cases. Also, the two estimates of HIV incidence and prevalence obtained from back-calculation on both AIDS mortality data and the number of AIDS reported cases were very similar, although there was more variability in the estimates obtained from mortality data.

Acquired Immunodeficiency Syndrome↗

PubMed1995

A back-calculation method to estimate the age and period HIV infection intensity, considering the susceptible population.

An extension of the back-calculation method to reconstruct the past history of HIV infections is presented. In this method the HIV infection intensity, as a function of age and calendar time, is assumed to belong to a family of parametric functions and is back-calculated from the observed AIDS incidence cases, knowledge of the incubation period and of the susceptible population, the final model being chosen as the one that gives the best fit. The model allows for the interaction between age and calendar time. The application to the main risk groups in Italy, male IVDUs and homosexuals, showed that age and the susceptible population were important in estimating the epidemic among IVDUs; interaction between age and calendar time was found to be significant, showing that among young IVDUs the risk of infection decreased faster than among older IVDUs. Sensitivity of the estimates to the assumption of population and choice of the infection function is investigated.

Acquired Immunodeficiency Syndrome↗

PubMed1994

A stochastic model for neuronal bursting.

A new stochastic model for bursting of neuronal firing is proposed. It is based on stochastic diffusion and related to the first passage time problem. However, the model is not of renewal type. Its form and parameters are physiologically interpretable. Parametric and non-parametric inferential issues are discussed.

Action Potentials↗

PubMed1992

Estimation of the acquired immunodeficiency syndrome incubation period in intravenous drug users: a comparison with male homosexuals.

Estimates of the risk of developing acquired immunodeficiency syndrome (AIDS) have been limited to studies involving homosexual men, transfusion recipients, and hemophiliac subjects. Little is known, however, about the natural history of the human immunodeficiency virus infection in intravenous drug users. An Italian multicenter cohort study of 420 individuals who seroconverted between 1982 and 1990 provided the opportunity to study the incubation period to AIDS in this group. A three-state Markov model was fitted to the data, and estimates of the risk of developing AIDS were obtained for intravenous drug users, male homosexuals, and three age groups. The risk of developing AIDS increased significantly with age. The estimated annual risk of developing AIDS for individuals between 25 and 34 years of age and over 35 years was 2.4 and 3.8 times higher, respectively, than that observed for individuals between 16 and 24 years of age. The mode of transmission did appear to have a small but not statistically significant influence on the time interval between the diagnosis of AIDS-related conditions and AIDS.

Acquired Immunodeficiency Syndrome↗