Estimation of the risk of tubal factor infertility associated with genital chlamydial infection in women: a statistical modelling study

Objectives Using a statistical modelling approach, our study aim is to determine reliable age-related estimates of the risk of all-cause tubal factor infertility (TFI) following past or current chlamydial infection in women in Scotland.

Method Using data from several sources, a Markov-Chain Monte Carlo model was used to estimate the age-related risk of TFI given genital chlamydia infection at any time. The analysis is based on the probability of a woman ever having chlamydial infection, ever having TFI and ever having a previous chlamydial infection given a diagnosis of TFI. The model was programmed and evaluated using WinBugs14.

Results By the age 44 years, the overall risk of a woman having at least a single chlamydial infection is estimated at 42.9% (95% credible interval 30.0, 59.0%). The risk of a woman having TFI increased from 0.5% in those aged 16–19 years to 0.8% in those aged 40–44. The overall estimated probability of TFI, based on lifetime infertility, given a past or current chlamydial infection, is relatively consistent across all five age groups from 16–44 years, being 0.9% among those aged 25–29 and 1.4% in those aged 35–39; The estimates were found to be sensitive to the definition of infertility, with the estimate increasing from 1.3% in the youngest age group to 2.8% and 4.5% for 24-month primary infertility and primary or secondary infertility, respectively.

Conclusions At the population level, the likelihood of all-cause TFI in those with past or current chlamydial infection is low. These findings have relevance both at the policy level, in the development of control programmes, and also at an individual level, particularly for clinicians supporting women undergoing testing or with a positive diagnosis.