Comparison of IgG serum antibodies, electronic health records and self-report in estimating past infection with Chlamydia trachomatis in a cohort of men who have sex with men.

Background The best method for measuring a history of Chlamydia trachomatis (CT) infections is unknown. We examined the reliability of three methods as markers of past CT infections: IgG serum antibodies, the electronic health record (EHR) and self-report. Methods This cross-sectional study used data from a cohort study of 122 MSM in King County, Washington, United States. Sera were tested for IgG using the mixed CT peptide enzyme-linked immunosorbent assay (ELISA). Participant data for past CT diagnoses were extracted from the EHR. Self-report of past CT was collected via survey. We calculated positive and negative percent agreements of CT history using total IgG serum antibodies to CT, past EHR diagnosis and self-report of past CT as reference measures when they were compared with one another. Results Of those who were IgG seropositive, only 41.5% had a past diagnosis of CT in their EHRs, but 74.4% self-reported a history of CT. The majority (92.7%) of participants who had a diagnosis of CT in their EHRs reported a past CT infection. Conclusions Self-report in combination with IgG serum antibodies to CT may be a more reliable indicator of past CT than EHRs in settings without comprehensive EHRs.