Scoring system avoids Chlamydia trachomatis over-screening in women seeking surgical abortion
Vincent Lavoue1, Marie Catherine Voltzenlogel1, Camille Leonardon1, Jacques Minet1, Patrice Poulain1, Margaret Redpath2, Cyrille Huchon3 1Teaching Hospital of Rennes, Rennes, France, 2McGill University, Montreal (Qc), Canada, 3Université de Montréal, Montreal (Qc), Canada - email@example.com
Objective To develop and validate a predictive score to avoid unnecessary screening and prophylactic antibiotic use in abortion clinics by identifying a group of women who are at very low risk of Chlamydia trachomatis (CT) infection. Methods: This population-based retrospective study includes 1000 women who underwent surgical abortion between January and September 2010. The main outcome measure was the rate of CT infection among women seeking an induced abortion according to socio-demographic and clinical data. The score was developed by using 2/3 of the dataset as the derivation sample to identify the strongest predictors of CT. An ROC curve established cutoffs, and applied the score to the remaining 1/3 (validation sample). Results The rate of CT infection was 6.7%. Three criteria were independently associated with CT: gestation >10 weeks [adjusted odds ratio (aOR), 1.96; 95% confidence interval (95% CI), 1.06-3.64], not using contraception (aOR, 2.70; 95% CI, 1.41-5.16) and having 0 or 1 child (aOR, 3.46, 95% CI, 1.34-8.93). The CT score was based on these three criteria. The low risk group was derived from values of the score [probability of CT, 1.3% (95% CI, 0-3.0)]. Application of these criteria to the validation dataset confirmed the diagnostic accuracy of the score (probability of CT, 0%). Sensitivity was 100% and specificity 26.9% for the score in the validation dataset. Applied to the validation dataset, the score avoided 25.4% of CT tests and screened of 100% of CT-infected women before surgical abortion. Conclusions This easy-to-calculate score may prove useful for avoiding CT test in 25% of patients seeking surgical abortion.