The Cost-Effectiveness of Screening for Genital Chlamydial Infection in the UK

This PhD thesis explores the cost-effectiveness of Chlamydia trachomatis (CT) screening, in the context of the National Chlamydia Screening Programme (NCSP) currently being implemented in England. It uses statistical, mathematical and economic modelling techniques and methods. The epidemiology ofCT in the UK is explored by identifying studies through a systematic literature review. The data from them are extracted and analysed using regression techniques and CT prevalence is estimated, indicating a high burden in young women in health care settings. The prevalence estimates are used along with data on past CT treatment and sexual mixing behaviour to parameterise an individual-based dynamic mathematical model of CT transmission:' An extensive fitting process identified parameter values that generated realistic epidemiology and sexual behaviour, to optimise public health applicability ofthe model. The cost of offering CT screening is estimated based on empirical data from a screening study. The flow of patients through a screening programme is modelled and the associated costs of testing and treatment of positives are estimated. Results from the sensitivity analyses indicate that the proportion of individuals accepting a screening offer has the biggest impact on the results, and highlight how costs could be minimised. In the final analysis, results ofthe parameterised dynamic model are combined with an economic model of disease progression and costs to estimate the cost-effectiveness of the NCSP strategy and alternatives. Results indicate that the current NCSP strategy (screen women and men aged under 25 years) may be cost-effective when compared to no screening, but that alternate, less inclusive strategies may be more acceptable on cost-effectiveness grounds. Assumptions about the progression from CT to pelvic inflammatory disease have the largest impact on the results