Rationale, public health approaches, and policy implications of implementing community-level screening programmes for Chlamydia trachomatis infection.

This context statement outlines my published research in three themes adapted from the ten criteria for screenings established by Wilson and Jungner (1968) Chlamydia trachomatis as a public health problem implementation of large-scale chlamydia screening programmes; and monitoring and evaluation of chlamydia screening programmes. These themes are supported by seven published papers quantifýing the epidemiology of chlamydial infection in several populations; describing the development, implementation and first year results of a national chlamydiac screening programme; and demonstrating four methods of evaluation - assessment of screening criteria, use of positivity to measure disease changes in the population clinical audits of provider ddherence to screening guidelines and fiscal
analysis of costs through economic modelling.
My research utilised a diverse set of study designs and methodological approaches: a) confirmatory studies of previously published research; b) cross-sectional studies with differing levels of statistiscal sophistication c) clinical policy review using questionnaires to health care providers d) economic modelling of budget expenditures and decision-tree and sensitivity analyses and e) an evaluation of a chlamydia screening programme combining retrospective cross-sectional analysis and multivariate logistic regression with sensitivity and efficiency analyses.
My research has revealed significant levels of chlamydia morbidity in a variety of populations and settings in the United States and United Kingdom and has demonstrated
consistently increasing trends in rates of diagnosed chlamydial infections among genitourinary medicine(GUM) clinic attenders in the UK. These data suggest that chlamydial infection is a prevalent disease in both countries and contributes to a significant global public health problem. I have examined the genesis of a new national chlamydia screening programme in the UK, and have shown the continued feasibility and acceptability of chlamydia screening , affirmed that screening in high prevalence populations is a successful strategy for disease detection, and improved our understanding of the sexual
behaviours that continue to drive this epidemic. My evaluation of the longest running chlamydia screening programme in the US has illustrated the value of periodic assessments in screening protocols and lead to the revision in selection criteria for women screened in the north western US. I have found utihty in a variety of methods to monitor and evaluate chlamydia screening programmes. The application of sensitivity and efficiency thresholds
to sets of screening criteria proved useful in evaluating c riteriap erformancea ndi ncreasing criteria efficiency. Using chlamydia test positivity as a surrogate measure for prevalence could adequately measure programme impact for the National Chlamydia Screening Programme in England. Clinical audits of service providers regarding published guidelines for chlamydia screening in termination of pregnancy services demonstratpd practice variation for chlamydia screening in these settings and suggested harmonisation of guidelines to increase adherence. Finally, my research of screening programme costs using economic models proved a useful tool to explore the average costs of screening and variations in estimates as local programmes revise their implementation and operational structure for chlamydia screening, and recommend this method be used to inform resource allocation for future phases of the National Chlamydia Screening Programme in England.

Submitted in partial fulfilment of PhD requirements.