A copula approach to sample selection modeling of treatment adherence and viral suppression among HIV patients on antiretroviral therapy (ART) in Namibia select="/dri:document/dri:meta/dri:pageMeta/dri:metadata[@element='title']/node()"/>

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dc.contributor.author Nakaluudhe, Jason
dc.date.accessioned 2019-06-11T06:28:12Z
dc.date.available 2019-06-11T06:28:12Z
dc.date.issued 2019
dc.identifier.uri http://hdl.handle.net/11070/2540
dc.description A mini thesis submitted in fulfillment of the requirements for the Degree of Master of Science (Biostatistics) en_US
dc.description.abstract Namibia has a generalized human immunodeficiency virus (HIV) epidemic, with HIV mainly transmitted through heterosexual transmission. Although the number of people receiving ART has increased, the achievement of the 90-90-90 strategy on testing, treatment and suppression has not been evaluated. Moreover, examining factors associated with treatment adherence and viral suppression will assist in designing appropriate accelerated interventions. However, modelling treatment adherence and viral suppression may result in biased estimates if sample selection is ignored. The study fit a joint distributional model of ART treatment adherence and viral suppression, to adjust for sample selection bias among HIV patients on ART in Namibia, to examine the presence of tail dependence in sample selection bias, and investigate the factors associated with viral suppression, viral load and ART adherence. The study used two datasets; HIV data of patients, aged above 16 years, on antiretroviral therapy in Erongo region and the selected health facilities in Windhoek, Namibia. A Heckman-type selection analysis using copula were used on the two models: (i) ART adherence with viral suppression margins and (ii) ART adherence with viral load. The families of copulas i.e. Normal, Frank, FGM, AMH, Student-t and the 0, 90, 180 and 270 degrees rotated versions of Joe, Gumbel and Clayton, to capture dependence in the outcomes, were modelled and selected based on the lowest AIC and BIC. The results showed a strong negative correlation between adherence to ART treatment and viral load suppression. The results also showed the dependence structure between ART adherence and viral load margins. The results further showed that Frank and the 180 degrees rotated versions of Gumbel, and Clayton copulas were the best models. Antiretroviral therapy adherence with viral suppression and ART adherence with viral loads exhibit positive dependence structures, even though some demographic and clinical characteristics were not associated with ART adherence, viral suppression and viral load. Similar studies in the future need to consider socio-economic factors in addition to those considered in this study. en_US
dc.language.iso en en_US
dc.publisher University of Namibia en_US
dc.subject HIV en_US
dc.subject Antiretroviral therapy en_US
dc.title A copula approach to sample selection modeling of treatment adherence and viral suppression among HIV patients on antiretroviral therapy (ART) in Namibia en_US
dc.type Thesis en_US


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