Selective screening for chlamydial infection: which criteria to use?

BACKGROUND: Screening sexually active women for Chlamydia trachomatis is necessary to detect asymptomatic infections. Selective screening is a common strategy because universal screening is too costly in many settings. In order to guide local programs in the choice of selective screening criteria, we examined the performance of previously proposed screening criteria for C. trachomatis. METHODS: A clinic-based, cross-sectional study was conducted in public family planning and sexually transmitted disease (STD) clinics in ten counties in North Carolina. Women (n = 4471 in family planning and n = 2201 in STD clinics) undergoing pelvic examination were enrolled consecutively. Nine sets of screening criteria, including age alone, were compared using sensitivity, specificity, number of tests required and receiver-operator characteristic (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 planning 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 infections while screening 51% of women. In STD clinics, the same criteria would detect 83% of infections but require testing 67% of women. Testing women aged < or =22 would detect 77% of infections in family planning and 74% of infections in STD clinics, while testing 51% and 48% of the women, respectively. CONCLUSIONS: When site-specific criteria cannot be developed, age alone is an acceptable strategy for selective screening for chlamydial infection.

Performance of the Kodak DT-60 physician's office analyzer as measured by CLIA-88 proposed evaluation criteria. Assessment of demographic and quality assurance factors influencing performance.

The 1988 Clinical Laboratories Improvement Act (CLIA-88) proposes to mandate universal proficiency testing and internal quality assurance practices for all laboratories, including those in physician offices. For 3 years, we have provided an independent voluntary proficiency testing program to more than 400 physician office laboratories using Kodak DT-60 analyzers (Eastman Kodak, Rochester, NY). This unique data set enables us to evaluate, using the CLIA-88 proposed grading criteria, the ability of these laboratories to meet the proposed regulatory standards. Using the equivalent of a year's participation under the CLIA proficiency testing format (20 challenges per analyte), at least 88% would "pass," ie, achieve acceptable performance. We investigated the relationship between proficiency testing performance and several internal quality assurance practices as well as other factors commonly associated with quality performance, including analyst's professional background, monthly test volume, number of physicians served, and source of training on the instrument. The best indicator of successful performance in proficiency testing was on-site training provided by the manufacturer, as opposed to training provided by distributor personnel. We conclude that with proper on-site training and retraining, physician office laboratories will be able to meet the mandatory CLIA-88 proficiency testing requirements.