A field test of the effects of instruction design on colorectal cancer self-screening accuracy.

A field experiment tested whether instruction design improves accurate adherence to instructions for medical do-it-yourself tests like the Fecal Occult Blood Test (FOBT). As part of an outreach campaign, 16,073 participants received FOBTs with instructions that were (i) human factored, (ii) motivational, (iii) human factored/motivational combined, or (iv) the standard used in the past. Among all test results returned (N = 2483), only the human factors instructions reduced errors in filling out result cards. However, after post-validating result cards that had errors, the human-factored, motivational and merged instructions reduced errors. The present findings show that medical instructions designed with human factors and persuasion principles increase accurate adherence. These design principles provide simple and cost-effective ways to increase test taking accuracy and FOBT effectiveness. Better screening instructions can improve the chances of detecting colorectal cancer early, which may help to decrease cancer mortality.