Risk factors for Chlamydia trachomatis infection in 6810 young women attending family planning clinics.

Screening programmes are important for the control of Chlamydia trachomatis (Ct) infection, a disease spread mainly by asymptomatic carriers. Risk factors for Ct infection were assessed in 6810 consecutive asymptomatic young women seeking contraceptive advice. All women filled in a questionnaire and were offered Ct testing. Of the 5785 who consented to testing, 425 (7.3%) were Ct culture positive. Four variables were significantly related to increased risk of being infected: age 18-23 years, duration of present relationship less than 1 year, non-use of condoms, and a history of not having had a previous genital infection. It is not possible to devise screening criteria that would effectively identify women at high risk. Therefore a screening programme should be targeted at all sexually active young people. However, if after some years the programme succeeds in lowering general Ct prevalence, these factors may be important when selecting patients for Ct testing.