Use of statistical modelling and analyses of malaria rapid diagnostic test outcome in Ethiopia.
Year: 2013
Type: dissertation
Abstract: The transmission of malaria is among the leading public health problems in \nEthiopia. From the total area of Ethiopia, more than 75% is malarious. Identifying \nthe infectiousness of malaria by socio-economic, demographic and geographic risk \nfactors based on the malaria rapid diagnosis test (RDT) survey results has several \nadvantages for planning, monitoring and controlling, and eventual malaria \neradication effort. Such a study requires thorough understanding of the diseases \nprocess and associated factors. However such studies are limited. Therefore, the \naim of this study was to use different statistical tools suitable to identify socioeconomic, \ndemographic and geographic risk factors of malaria based on the \nmalaria rapid diagnosis test (RDT) survey results in Ethiopia. A total of 224 \nclusters of about 25 households were selected from the Amhara, Oromiya and \nSouthern Nation Nationalities and People (SNNP) regions of Ethiopia. Accordingly, \na number of binary response statistical analysis models were used. Multiple \ncorrespondence analysis was carried out to identify the association among socioeconomic, \ndemographic and geographic factors. Moreover a number of binary \nresponse models such as survey logistic, GLMM, GLMM with spatial correlation, \njoint models and semi-parametric models were applied. To test and investigate how well the observed malaria RDT result, use of mosquito nets and use of indoor residual spray data fit the expectations of the model, Rasch model was used. The fitted models have their own strengths and weaknesses. Application of \nthese models was carried out by analysing data on malaria RDT result. The data \nused in this study, which was conducted from December 2006 to January 2007 by \nThe Carter Center, is from baseline malaria indicator survey in Amhara, Oromiya \nand Southern Nation Nationalities and People (SNNP) regions of Ethiopia. \nThe correspondence analysis and survey logistic regression model was used to \nidentify predictors which affect malaria RDT results. The effect of identified socioeconomic, \ndemographic and geographic factors were subsequently explored by \nfitting a generalized linear mixed model (GLMM), i.e., to assess the covariance \nstructures of the random components (to assess the association structure of the \ndata). To examine whether the data displayed any spatial autocorrelation, i.e., \nwhether surveys that are near in space have malaria prevalence or incidence that \nis similar to the surveys that are far apart, spatial statistics analysis was \nperformed. This was done by introducing spatial autocorrelation structure in \nGLMM. Moreover, the customary two variables joint modelling approach was \nextended to three variables joint effect by exploring the joint effect of malaria RDT \nresult, use of mosquito nets and indoor residual spray in the last twelve months. \nAssessing the association between these outcomes was also of interest. \nFurthermore, the relationships between the response and some confounding \ncovariates may have unknown functional form. This led to proposing the use of \nsemiparametric additive models which are less restrictive in their specification. \nTherefore, generalized additive mixed models were used to model the effect of age, \nfamily size, number of rooms per person, number of nets per person, altitude and \nnumber of months the room sprayed nonparametrically. The result from the study \nsuggests that with the correct use of mosquito nets, indoor residual spraying and \nother preventative measures, coupled with factors such as the number of rooms in \na house, are associated with a decrease in the incidence of malaria as determined \nby the RDT. However, the study also suggests that the poor are less likely to use \nthese preventative measures to effectively counteract the spread of malaria. In \norder to determine whether or not the limited number of respondents had undue \ninfluence on the malaria RDT result, a Rasch model was used. The result shows \nthat none of the responses had such influences. Therefore, application of the \nRasch model has supported the viability of the total sixteen (socio-economic, \ndemographic and geographic) items for measuring malaria RDT result, use of \nindoor residual spray and use of mosquito nets. From the analysis it can be seen \nthat the scale shows high reliability. Hence, the result from Rasch model supports the analysis carried out in previous models.
Author: Dawit Getnet Ayele
Language: English
Topic: Malaria Research and Control
Field: Medicine
Domain: Health Sciences
Open Access status: green
Funder: Carter Center
OpenAlex ID: W1522610934