Proportion of Pelvic Inflammatory Disease Cases Caused by Chlamydia trachomatis: Consistent Picture From Different Methods.
Pelvic inflammatory disease (PID) is a leading cause of both tubal factor infertility and ectopic pregnancy. Chlamydia trachomatis is an important risk factor for PID, but the proportion of PID cases caused by C. trachomatis is unclear. Estimates of this are required to evaluate control measures.



We consider 5 separate methods of estimating age-group-specific population excess fractions (PEFs) of PID due to C. trachomatis, using routine data, surveys, case-control studies, and randomized controlled trials, and apply these to data from the United Kingdom before introduction of the National Chlamydia Screening Programme.



As they are informed by randomized comparisons and national exposure and outcome estimates, our preferred estimates of the proportion of PID cases caused by C. trachomatis are 35% (95% credible interval [CrI], 11%-69%) in women aged 16-24 years and 20% (95% CrI, 6%-38%) in women aged 16-44 years in the United Kingdom. There is a fair degree of consistency between adjusted estimates of PEF, but all have wide 95% CrIs. The PEF decreases from 53.5% (95% CrI, 15.6%-100%) in women aged 16-19 years to 11.5% (95% CrI, 3.0%-25.7%) in women aged 35-44 years.



The PEFs of PID due to C. trachomatis decline steeply with age by a factor of around 5-fold between younger and older women. Further studies of the etiology of PID in different age groups are required.
Institute of Applied Health Research, University of Birmingham.
Malcolm J
MJ
Price
School of Social and Community Medicine, University of Bristol.
A E
AE
Ades
School of Social and Community Medicine, University of Bristol.
Nicky J
NJ
Welton
Bristol Sexual Health Centre, University Hospital Bristol NHS Foundation Trust, United Kingdom.
Ian
I
Simms
School of Social and Community Medicine, University of Bristol.
John
J
Macleod
School of Social and Community Medicine, University of Bristol Public Health England, London.
Paddy J
PJ
Horner
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002690:Chlamydia Infections / Q000453:epidemiology* / Q000382:microbiology*; D002692:Chlamydia trachomatis / Q000302:isolation & purification*; D005260:Female; D006801:Humans; D000292:Pelvic Inflammatory Disease / Q000453:epidemiology* / Q000382:microbiology*; D011247:Pregnancy; D006113:United Kingdom / Q000453:epidemiology; D055815:Young Adult
Bayesian; Chlamydia trachomatis; evidence synthesis; meta-analysis; pelvic inflammatory disease; population attributable fraction; population excess fraction