Number of chlamydia diagnoses per capita not associated with rates of ectopic pregnancies and female infertility - An ecological study

Background
Tubal infertility and ectopic pregnancies are serious, but rare, complications of chlamydia infections. It is unclear whether chlamydia screening in women has an impact on these complications. Chlamydia incidence rates between European countries vary by orders of magnitude, which largely reflects different intensities of screening.
Methods
We used chlamydia diagnoses rates as a proxy for chlamydia screening rates to assess if differences in screening intensity were associated with differences in the frequency of ectopic pregnancy and the prevalence of infertility in women. We used mixed effects linear regression to assess for an association between chlamydia screening intensity in European countries and two outcomes: (1) the incidence of ectopic pregnancy and (2) the prevalence of infertility in women, while controlling for year, income and quality of health services.
Results
The number of countries with available data increased from 3 in 1990 to 23 in 2019, before slightly declining to 22 in 2020. CT incidence varied across countries, from a median of 207 cases per 100,000 in 1990 (IQR: 59–313) to 33 cases per 100,000 in 2021 (IQR: 3–179). There was less variation in ectopic pregnancy incidence (median: 208 and 33 per 100,000 in 1990 and 2021, respectively), and female infertility prevalence (median 1,224 and 1,587 per 100,000 in 1990 and 2021, respectively). No association was found between screening intensity and ectopic pregnancy incidence or infertility prevalence after adjusting for year, GDP per capita, and universal health coverage index.
Conclusions
Our results are compatible with other types of data that suggest that the intensity of screening for chlamydia is not associated with a large effect on the population-level frequency of all ectopic pregnancies and female infertility.