Colorectal cancer screening in the Iowa Research Network (IRENE): a validity assessment of patient self-report of up-to-date status

Patient self-report of colorectal cancer (CRC) screening remains a critical source of information in determining adherence to recommended guidelines. Accurate assessment is important for clinical decision-making, quality assurance and research. Population subgroup differences can affect self-report accuracy. Studies relying on patient self-report benefit from assessing validity and attempting to quantify measurement error and bias. This study assessed self-reported CRC screening data accuracy, estimating overall and test-specific adherence, and evaluated associations between predictor variables and accuracy that might explain variation in estimates.

1,399 patients aged 51-80 years from 16 family medicine offices completed an investigator-developed questionnaire and had medical records (MRs) available. Comparison of self-report of up-to-date screening with test documentation in the MR was used to estimate validity; multivariable analysis assessed predictors of concordance, or agreement between self-report and test documentation in the MR.

Sixty percent of patients reported they were up-to-date with CRC screening by any test, while 48% had screening documented in the MR. Nearly all documentation was for colonoscopy. Education, insurance source, CRC family history and patient duration in office, adjusted for all other variables in the final model, were significant predictors of concordance. Age modified a significant association with concordance for patient rural-urban residence and for recency of last visit.

Self-reported CRC screening validity was generally acceptable, but overreporting was prevalent across all tests. MR documentation of CRC screening was almost exclusively based on colonoscopy. Concordance between self-reported colonoscopy and the MR was good but varied with patient characteristics, healthcare utilization practices and rural-urban residence.