RESUMEN
OBJECTIVE: To determine the prevalence and determinants of Chlamydia trachomatis (CT) infections among asymptomatic men and women in general practice. To determine participation rates in a systematic screening programme in general practice, using home obtained mailed urine samples. DESIGN: Cross-sectional study. METHODS: In 15 general practices in Amsterdam, the Netherlands, a sample of 11,005 persons (5541 women and 5464 men), aged 15-40 were invited to send in a urine sample and a completed questionnaire by mail. The urine samples were tested using the ligase chain reaction for DNA amplification. Patients diagnosed with CT were treated and partner notification was performed. RESULTS: 33% of invited males (1809/5464) and 50% of females (2751/5541) sent in the study material. Older patients participated more frequently than younger patients. Participation rates among persons with a Dutch background were higher than rates among persons from other ethnic groups. In 42 men and 79 women a CT infection was identified (2.3% and 2.9% respectively). Infections were more prevalent in patients from Surinam and the Dutch Antilles and in the age category 21-25 years. Type of health insurance as a proxy measure of socioeconomic status was not an indicator of infection. CONCLUSION: The participation in this systematic screening using mail-sent urine samples was 33% in men and 50% in women. The CT prevalences among asymptomatic men and women were 2.3% and 2.9% respectively.