Selective screening for chlamydial infection: Which criteria to use?

Background: Screening sexually active women for Chlamydia trachomatis is ne cessary to detect asymptomatic infections. Selective screening is a common strategy because universal screening is too costly in many settings. In ord er to guide local programs in the choice of selective screening criteria, w e examined the performance of previously proposed screening criteria for C trachomatis. Methods: A clinic-based, cross-sectional study was conducted in public fami ly planning and sexually transmitted disease (STD) clinics in ten counties in North Carolina. Women (n = 4471 in family planning and n = 2201 in STD c linics) undergoing pelvic examination were enrolled consecutively. Nine set s of screening criteria, including age alone, were compared using sensitivi ty, specificity, number of tests required and receiver-operator characteris tic (ROC) analysis. All women underwent testing with ligase chain reaction assay of cervical specimens to identify C trachomatis infection. Results: The prevalence of C trachomatis was 7.8% and 11.0% in family plann ing and STD clinics, respectively. The sensitivities of published criteria ranged from 0.50 to 0.97. Specificities ranged from 0.05 to 0.66. In family planning clinics, the best performing criteria would detect 84% of infecti ons while screening 51% of women. In STD clinics, the same criteria would d etect 83% of infections but require testing 67% of women. Testing women age d less than or equal to 22 would detect 77% of infections in family plannin g and 74% of infections in STD clinics, while testing 51% and 48% of the wo men, respectively. Conclusions: When site-specific criteria cannot be developed, age alone is an acceptable strategy for selective screening for chlamydial infection.