Accuracy of self-reported reason for colorectal cancer testing

Abstract

Assessment of accuracy of self-reported reason for colorectal cancer testing has been limited. We examined the accuracy and correlates of self-reported reason (screening or diagnosis) for having a sigmoidoscopy or colonoscopy. Patients who had received at least one sigmoidoscopy or colonoscopy within the past 5 years were recruited from a large multispecialty clinic in Houston, TX, between 2005 and 2007. We calculated concordance, positive predictive value, negative predictive value, sensitivity, and specificity between self-reported reason and the medical record (gold standard). Logistic regression was performed to identify correlates of accurate self-report. Self-reported reason for testing was more accurate when the sigmoidoscopy or colonoscopy was done for screening, rather than diagnosis. In the multivariable analysis for sigmoidoscopy, age was positively associated with accurately reporting reason for testing, whereas having two or more colorectal cancer tests during the study period (compared with only one test) was negatively associated with accuracy. In the multivariable analysis, none of the correlates was statistically associated with colonoscopy although a similar pattern was observed for number of tests. Determining the best way to identify those who have been tested for diagnosis, rather than screening, is an important next step.

Figure 1

Flow diagram showing how the sample of participants was chosen