Comparison of self-reported and test-identified chlamydial infections among young adults in the United States of America

Abstract

Many studies rely on respondent reports of prior diagnosed sexually transmissible infections (STIs), but these self reports are likely to under-estimate infection prevalence. The extent of bias from using self-reported STI data, and whether bias varies by sex and race, is largely unknown. This gap is addressed using a large, nationally representative sample. Cross-sectional analyses of Wave III of the National Longitudinal Study of Adolescent Health. Participants were 18-26 years old (n = 12,359). Estimates of the prevalence of chlamydial infection based on self-reported diagnoses in the past year were compared with actual prevalence based on nucleic acid amplification testing (NAAT) at the time of data collection. Ratios of test-identified prevalence to self-reported diagnosis prevalence were calculated by sex and race/ethnicity groups. Larger ratios indicate greater extent of self reports under-estimating infection prevalence. About 4.2% of the sample had a current NAAT-identified chlamydial infection, but only 3.0% reported having been diagnosed with chlamydia in the past year, yielding a ratio of 1.43. The ratio of test-identified infection prevalence to prevalence identified from self-reported diagnoses was larger among men than women (2.07 versus 1.14, P < 0.05). Among men, the ratio was larger among non-Hispanic blacks (2.40) compared with non-Hispanic whites (1.07, P < 0.05). Use of self-reported diagnoses under-estimates chlamydial infection prevalence, particularly among men, and among non-Hispanic black men. Reliance on self-reported STIs may consequently lead to biased conclusions, particularly for these groups. Use of biological testing for STIs in research studies is recommended.