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UBC Theses and Dissertations

A new method of integrating epidemiological and health services modelling techniques for studying infectious diseases : an example using HIV/AIDS Johnston, Karissa Michelle


Since the introduction in 1996 of highly active antiretroviral therapy (HAART) for treating individuals infected with HIV, morbidity and mortality among individuals who access care in a timely fashion have dramatically decreased. As a result, patterns of health services utilization have shifted from hospitalizations and acute care services to outpatient services and medications. An additional implication of increased HAART coverage has been a reduction in HIV-1 viral load amongst treated individuals. Individuals with lower viral load are less likely to transmit HIV infection to uninfected individuals. A resulting hypothesis is that increasing treatment with HAART—either by treating individuals earlier in their infection or by expanding treatment coverage rate to a greater proportion of infected individuals—could potentially lead to reduced rates of HIV transmission. To date, the results of ecological studies and mathematical modelling studies have been consistent with this hypothesis. The objectives in this dissertation were: to build a computational tool that could be used to answer complex questions regarding the economics of HIV during the HAART era in British Columbia (BC), Canada; and to address specific economic questions relevant to the current treatment of HIV in BC. The particular questions of interest included: the monthly costs associated with various categories of health services utilization and the correlation between categories (Chapter 3); the expected long-term incidence and costs associated with hospitalizations after initiation of HAART (Chapter 4); the lifetime direct medical costs associated with an individual infected with HIV during the HAART era (Chapter 5); and the cost-effectiveness of a strategy to increase HAART coverage from 50% to 75% of clinically eligible individuals, accounting for individual-level and population-level effects of HAART (Chapter 6). These questions were addressed using a variety of statistical and mathematical techniques, based on a BC-specific population-based data source. A key finding with important public health relevance was that use of HAART was associated with decreases in other categories of direct medical costs. These cost offsets were due to both an improvement in morbidity resulting in a reduced need for acute health care services and, more importantly, a reduction in HIV incidence.

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