Screening for chlamydial infections and the risk of ectopic pregnancy in a county in Sweden: ecological analysis

Abstract

Objectives: To analyse trends in rates of genital chlamydial infection and ectopic pregnancy between 1985 and 1995 in a county in Sweden. Setting: Uppsala county where screening for chlamydial infection, treatment, and contact tracing has been widespread and where ectopic pregnancies are recorded. Methods: Rates of chlamydial infections and ectopic pregnancy between 1985 and 1995 were calculated for women aged 20-39 years. Poisson and linear regression were used to examine the association between the risk of ectopic pregnancy and the current rates of chlamydial infection and rates of chlamydial infection from up to 5 years earlier. Main outcome measures:Rates of chlamydial infection per 100 examinations, rates of ectopic pregnancy per 1000 pregnancies, rate ratios and 95% confidence intervals for an increase in chlamydial infections of 5 new cases per 100 examinations. Results: 103 870 cervical samples from women aged 15-39 years were analysed; 5648 (5.4%) were positive for chlamydia. 51 630 pregnancies were analysed; 930 (1.8%) were ectopic. Both rates declined over time. For women aged 20-24 years there was a strong correlation between the rate of ectopic pregnancy and the rate of chlamydial infection in the same year (r = 0.93, P < 0.001); among older women correlations were stronger with rates of chlamydial infection occurring 1 or 2 years earlier. In Poisson regression ectopic pregnancy was most strongly associated with the current rate of chlamydial infection among women aged 20-24 (rate ratio 1.85, 95% confidence interval 1.44 to 2.38), with the rate of infection 1 year earlier among 25-29 year olds (rate ratio 1.72, 1.33 to 2.22) and 30-34 year olds (rate ratio 2.27, 1.53 to 3.37); and with the rate 2 years earlier among 35 to 39 year olds (rate ratio 2.58, 1.45 to 4.60). Conclusions: Declining rates of genital chlamydial infections have probably led to a fall in the rate of ectopic pregnancies. The timing of the decline in the rate of ectopic pregnancies varies with age. Among young women falling rates of chlamydial infection have been accompanied by an immediate reduction in the rate of ectopic pregnancy.

The accuracy and efficacy of screening tests for Chlamydia trachomatis: a systematic review

“…The incidence of pelvic inflammatory disease and its sequelae has fallen markedly in countries like Sweden and parts of the USA where there are screening programmes for chlamydia. More recently, Egger et al [98] have shown that the rate of ectopic pregnancy reduced in the first year after the introduction of screening.…”

Risk factors for genital chlamydial infection

“…The incidence of genital chlamydia began to decrease during the late 1980s, in association with the implementation of routine screening of women, increased screening among men, contact tracing and the establishment of youth clinics (16,(26)(27)(28)(29). The number of reported cases dropped from approximately 40,000 cases in 1987 to 14,000 cases in 1996, which has been accompanied by a corresponding reduction in the number of cases of PID and ectopic pregnancy (29-31).…”

C. trachomatis and N. gonorrhoeae surveillance in New Zealand: comparison of laboratory and clinic data

“…Integrated STI surveillance, together with screening guidelines for C. trachomatis, have been shown to reduce the incidence of infection and its sequelae. 19,20 Given the serious sequelae of C. trachomatis infections, 15 the probable under-diagnosis and under-reporting of disease, and the high rates of infection reported here, developing a national strategy for the management of STIs which incorporates screening and treatment guidelines for C. trachomatis and N. gonorrhoeae, as well as integrated national clinic and laboratory-based surveillance, should be considered a public health priority in New Zealand.…”