Abstract
BACKGROUND: Text message (short message service, SMS) interrogative reminders were adopted in population screening for the early detection of colorectal cancer (CRC). OBJECTIVE: This study aims to examine responses to text message (SMS) reminders and associate responses with senders' characteristics, message type (interrogative/declarative), and subsequent screening uptake. METHODS: We conducted a prospective cohort intervention. Text message (SMS) reminders to undergo CRC screening, randomized into interrogative and declarative phrasing, were sent to nonadherent 40,000 women and men (age 50-74 years) at CRC average risk. We analyzed recipient responses by message phrasing, recipient characteristics, and for content, the latter predicting subsequent CRC screening per program database. RESULTS: While interrogative text message (SMS) reminders elicited 7.67% (1475/19,227) responses, declarative ones elicited 0.76% (146/19,262) responses. Text message (SMS) responses were content analyzed and grouped into attitudes toward CRC screening (1237/1512, 81.8% positive) and intention to screen (1004/1512, 62.6%). Text message (SMS) respondents screened significantly more than nonrespondents after 6 months (415/1621, 25.6% vs 3322/36,868, 9.0%; χ12=487.5, P<.001); 1 year (340/1621, 21.0% vs 4711/36,868; χ12=91.5, P<.001); and 2 years (225/1621, 13.9% vs 3924/36,868; χ12=16.9, P<.001) following the reminders. In a multivariable logistic regression among text message (SMS) respondents, screening after 6 months was significantly predicted by older age, past sporadic screening, attitudes, and intentions. CONCLUSIONS: Interrogative text message (SMS) reminders reached previously uninvolved sectors in the CRC target population-men, sporadic-screenees, and the "never-tested" before. This novel application resulted in a population-level, incrementally enhanced screening. Asking patients about their future health behavior may be relevant for enhancing other health behaviors in preventive medicine and clinical settings.