The contribution of Chlamydia trachomatis to adverse reproductive health and the implications for control policy

Chlamydia is one of the commonest sexually transmitted bacterial infections in Europe. Most people have no symptoms, but left untreated it can cause serious complications, including infertility. Screening programmes can identify and treat asymptomatic people and reduce long-term complications. However these programmes have costs, personal and financial, that must be balanced against their benefit.

In order to do this we need to know how often complications occur after an infection. But the evidence on this is limited and based mainly on old studies that may not be relevant today.

The proposed research will review current knowledge about the association between chlamydia and reproductive health and then measure this association using information collected from residents of Manitoba Province, Canada, over the last 25 years. These findings will be used to develop a



mathematical model to estimate the potential impact of Chlamydia screening and to determine whether screening programmes are cost effective. Finally, interviews will be conducted with key professionals and public and patient representatives to understand the factors that influence screening policy. The research will conclude by drawing together the findings from each study to produce evidence based policy recommendations for Chlamydia screening.

Chlamydia trachomatis (CT) is one of the commonest sexually transmitted bacterial infections in Europe. Untreated infection can lead to serious adverse reproductive outcomes but these can be prevented by diagnosing and treating infections. The control of CT is a public health priority and there is evidence to show that screening can reduce the incidence of complications. Investment in control programmes is mainly justified in order to reduce long term complications, including pelvic inflammatory disease, ectopic pregnancy and tubal factor infertility. However, at present there are no consensus estimates of the risk of these complications following an infection.

The aim of this research is to improve knowledge about the natural history of CT infection and use this to estimate the population attributable risk of CT for adverse reproductive health in order to improve estimates of the cost effectiveness of CT control activities.

The gaps in the current evidence base around the natural history of CT and the cost effectiveness of control strategies will be addressed using a range of research methods. Firstly, a systematic review of the literature will be completed to update current estimates of the association between CT and adverse reproductive outcomes. Secondly, quantitative analysis of a large historical population cohort will be performed to measure the association between a diagnosis of CT and the chronic consequences. This work will then be used to inform the assumptions in a mathematical model of the transmission dynamics of CT that will be developed and used to inform cost effectiveness analysis of CT control strategies. Finally, qualitative techniques will be used to develop an understanding of the CT control policy context. The findings of the proposed research will be used to formulate policy recommendations.

The proposed research will provide a comprehensive multidisciplinary training in research and it will advance current knowledge on the natural history of CT and the cost effectiveness of control strategies to inform policy at a regional, national and international level.