The value of opportunistic chlamydia screening is called into question in this week's BMJ.

Dr Nicola Low, an epidemiologist at the University of Berne in Switzerland argues that claims about screening are not supported by rigorous research or practice.

And she shows how uncritical acceptance of the effectiveness of chlamydia screening in Sweden and the United States led to the funding of the National Chlamydia Screening Programme in England, before the balance of benefits and harms was understood.

Chlamydia trachomatis is a common, curable, easily diagnosed, sexually transmitted infection that usually causes no symptoms. It can, however, cause devastating complications, including infertility, ectopic pregnancy, neonatal infection, and facilitation of HIV transmission.

There are two types of screening programme proactive and opportunistic. Proactive screening uses population registers to invite people to be screened at regular intervals, while opportunistic screening targets people attending health services for unrelated reasons.

Chlamydia screening of selected groups is currently recommended in a range of health care settings in Sweden, the United States and Canada. In England, a programme offering opportunistic chlamydia screening to all sexually active women and men under 25 years is due to be implemented by 2008. Yet no randomised controlled trial has shown that this type of screening programme reduces long term illness.

Furthermore, most studies showing that chlamydia screening is cost effective do not satisfy accepted quality criteria for economic evaluations, says the author. They also tend to overestimate the cost effectiveness of chlamydia screening. Introducing a chlamydia screening programme is therefore likely to be an expensive intervention.

In Sweden, decreases in rates of chlamydia and its complications occurred at the same time as both widespread chlamydia testing and national
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Contact: Emma Dickinson
edickinson@bmj.com
44-020-738-36529
BMJ-British Medical Journal
5-Apr-2007