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Background: Both population-based surveys and health insurance claims data are used to estimate chlamydia screening coverage in the U.S. Estimates from these methods differ, and data directly comparing these two indices in the same population are limited.
Methods: In 2010, we surveyed a random sample of women aged 18-25 years enrolled in a Washington State health maintenance organization. Respondents were asked if they had been sexually active in the past 12 months and if they had been tested for chlamydia in that time. We linked survey responses to administrative records of chlamydia tests performed and reproductive services used, which comprise the HEDIS definition of the screened population and the sexually active population, respectively. We compared self-report and HEDIS using three outcomes: (1) sexual activity, among women with at least one healthcare visit (gold standard = self-report); (2) any chlamydia screening, among sexually active women (no gold standard); and (3) within-health plan chlamydia screening, among sexually active women (gold standard = HEDIS).
Results: Of 954 eligible respondents, 465 (49%) completed the survey; 377 (81%) of these consented to administrative medical record linkage. The mean age of these 377 women was 22 (SD=4.2) and 269 (71%) reported being sexually active. The sensitivity of HEDIS to identify sexually active women was 85% (95% CI=80%-89%) and the specificity was 64% (95% CI=52%-74%). Of 269 sexually active women, 108 (40%) had a chlamydia test in their administrative record but 142 (53%) self-reported being tested for chlamydia (kappa=0.35); 51 (19%) reported out-of-plan chlamydia testing. The sensitivity of self-reported within-plan chlamydia testing was 71% (95% CI=61%-80%) and the specificity was 81% (95% CI=73%-87%).
Conclusions: HEDIS may not accurately identify sexually active women. Self-reported chlamydia testing appears less sensitive than HEDIS for estimating screening coverage, but HEDIS underestimates screening coverage by excluding women who are tested out-of-plan.