A simple test can help assess how accurately patients report colorectal cancer screening
Research Activities, November 2010, No. 363
Clock drawing, a simple test of cognitive skills, can help predict whether an older patient's self-report about having been screened for colorectal cancer (CRC) or being up-to-date with CRC screening is accurate, a new study reports. By identifying patients likely to have impaired thinking, the clock drawing test can help clinician-researchers avoid using inaccurate information from patients in their research. The researchers reported that 493 patients participating in the study drew a clock, completed a questionnaire about their CRC screening, and had their questionnaire responses checked via chart review.
The patients, from practices that were part of the Iowa Practice-based Research Network, were asked to draw a clock showing "10 minutes after 11" on a preprinted circle. The researchers scored the clock drawings for the remaining 493 patients on a 0-7 scale (0-3 = normal, 4-7 = abnormal). The sensitivity of self-report for ever having had a colonoscopy was 82 percent for patients who drew normal clocks and 63 percent for those drawing abnormal clocks. The specificity for self-report of being up-to-date with colonoscopy screening was 79 percent for patients who drew normal clocks and 60 percent for patients who drew abnormal clocks.
In a model that included multiple variables, only abnormal clock drawing significantly predicted higher disagreement between self-report and chart review. Income, marital status, and age were not useful predictors of such disagreement. The study was funded in part by the Agency for Healthcare Research and Quality (HS14490).
More details are in "Patient clock drawing and accuracy of self-report compared with chart review for colorectal cancer (CRC) screening," by Jeanette M. Daly, Ph.D., Barcey T. Levy, M.D., Ph.D., Mrinalini Joshi, M.D., M.P.H., and others in the May/June 2010 Archives of Gerontology and Geriatrics 50(3), pp. 341-344.