Aims: To evaluate demographic characteristics of women terminating their pregnancy for sentinel surveillance of Chlamydia trachomatis infection and to report changing prevalences of C trachomatis over time within this study population.
Design: Screening for C trachomatis in women seeking induced abortion was introduced in 1984 at the Department of Gynecology, Regional Hospital, Trondheim, Norway. Over the study years our department has used a precoded medical record covering sociodemographic, medically relevant data, also recording outcome of the C trachomatis test. Throughout the study the Department of Microbiology applied cell culture, enzyme immunoassay, and, during the most recent years a nucleic acid test to identify C trachomatis.
Statistical methods: Chi square test for linear trend and unconditional logistic regression.
Results: Over the study period, women having induced abortion were characterised by being most often single and more often at younger age. The overall age-adjusted prevalence of C trachomatis declined from 9.2% in 1985 to 3.6% in 1995, the major decline occurring from 1987 to 1991, and affected all age-groups simultaneously. There was a 60% decrease in odds ratio of having a C trachomatis infection from 1985 to 1991, and the crude and the adjusted odds ratios did not differ for any year examined.
Conclusion: Women deciding on pregnancy termination have demographic characteristics that identify high-risk groups for C trachomatis infection. Despite these characteristics, which were relatively constant over the study period, the study population changed from being a high- to a low-prevalence population of C trachomatis.
PIP: Given the finding of a significant association between postabortion endometritis/salpingitis and the occurrence of Chlamydia trachomatis at the time of induced abortion, the Regional Hospital of Trondheim, Norway, initiated C trachomatis screening in all abortion patients in 1984. Screening is also performed at antenatal, family planning, and general practitioner visits. This study tracked the prevalence of C trachomatis from 1985 to 1995 as well as changes in the demographic characteristics of abortion patients. During the study period, the number of induced abortions varied from 872 in 1985 to 905 in 1989 and 756 in 1995. Most notable was an increase in the proportion of unmarried cohabitating women undergoing abortion and a 40% decrease in married abortion patients. The overall age-adjusted prevalence of C trachomatis declined from 9.2% in 1985 to 3.6% in 1995. The adjusted odds ratio of chlamydia infection decreased by more than 60% from 1985-91, followed by only minor changes. Age and marital status were the only demographic factors significantly predictive of chlamydia infection. The prevalence of C trachomatis was highest among teenagers and decreased significantly with increasing age. Single and cohabitating women were at greater risk of infection than married women. The number of chlamydia screenings performed each year increased from 2200 in 1985 to over 30,000 (almost 50% of sexually active women 15-44 years of age) in 1989. This high screening level, and subsequent treatment of infection, appears to have turned induced abortion patients from a high- to a low-prevalence population.