Comparison of HIV and Aids diseases mapping in Malaysia based on standardized Morbidity Ratio and Poisson-Gamma model

Human Immunodeficiency Virus (HIV) is the virus that causes chronic and life-threatening condition called Acquired Immune Deficiency Syndrome (AIDS). There is no currently available vaccine or cure for the disease. Therefore, to control the epidemic from continuing to spread will entirely depend on the control, treatment and prevention strategies. Disease maps have been recognized as one of the important tools in controlling diseases. Better statistical models used to estimate the relative risk will subsequently produce better disease risk maps. Therefore, the aim of this paper is to estimate the relative risk for HIV and AIDS in Malaysia based on the commonest method used in the study of disease mapping which are the Standardized Morbidity Ratio (SMR) and Poisson-Gamma models. In this paper, a review of the SMR method will be given and then will be applied to HIV and AIDS data in Malaysia. This application of SMR is then extended to the next method which is the Poisson-Gamma model and the results are compared in tables, graphs and maps. Result of the analyses shows that the latter model gives better estimation of relative risks compared with the SMR method due to the problem of SMR especially when there is no observed HIV and AIDS case in certain states in Malaysia. Notwithstanding, a major drawback of Poisson-Gamma is that the model does not allow for spatial correlation to exist between risks areas in adjacent areas and this has motivated many researchers to introduce other better alternative methods of relative risk and this estimation for disease mapping. Keywords HIV and AIDS cases, disease mapping, relative risk, Standardized Morbidity Ratio (SMR), Poisson-Gamma Model