There is a 5-fold decrease in the percentage of pelvic inflammatory disease (PID) caused by Chlamydia trachomatis as a woman gets older, according to data published in The Journal of Infectious Diseases.

Malcolm J Price, MSc, PhD of the Institute of Applied Health Research at the University of Birmingham in the United Kingdom and colleagues used routine surveys, case-control studies, and randomized controlled trials in the UK to estimate age-group-specific populations of patients with PID caused by C. trachomatis. The researchers focused on cases that occurred before the 2003 implementation of the National Chlamydia Screening Program.

Following their analysis of data, the researchers estimated that 35% (95% credible interval [CrI], 11%–69%) of women between the ages of 16-24 had C. trachomatis-related PID. That percentage dropped to 20% (95% CrI, 6%–38%) for women aged 16-44.

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There were some study limitations. The researchers noted that the diagnosis of PID is difficult because there is no single standard method and criteria threshold levels have changed.

PID is a major cause of ectopic pregnancy and tubal factor infertility. Researchers urged future studies on this topic that concentrate on the correlation between age and risk for PID and C. trachomatis.

“Further work establishing the degree of overlap between cases identified in different routine data sources is required. Finally, more focus should be placed on investigation of the role of non-STI vaginal microbiota in PID,” Dr Price and colleagues concluded.


1. Price MJ, Ades AE, Welton NJ, et al. Proportion of pelvic inflammatory disease cases caused by Chlamydia trachomatis: consistent picture from different methods. J Infect Dis. 2016;214(4)617-24. doi: 10.1093/infdis/jiw178. Published June 3, 2016. Accessed August 17, 2016.