Development and Validation of a Colorectal Cancer Screening Determinants Tool Using Protection Motivation Theory

Abstract

Background: Colorectal cancer (CRC) is one of the most common causes of cancer-related illness and death worldwide. Early detection of CRC through screening improves outcomes and decreases mortality; however, screening is still underutilized. While numerous factors influencing screening behaviors have been identified, no well-validated tools currently exist to fully explore these influences. The development of a valid and reliable assessment tool could clarify the factors that discourage or encourage people to undergo CRC screening, with the potential to increase participation rates. Objectives: The present study aimed to develop and validate a psychometrically sound colorectal cancer screening determinants tool (CCSDT) for people aged 50 - 70, based on the protection motivation theory (PMT). Methods: The cross-sectional study was conducted among people aged 50 - 69 from the Chaharmahal and Bakhtiari region of Iran, between July 15 and August 21, 2023. The total sample size was 500 people, with 250 participants used for exploratory factor analysis (EFA) and another 250 for confirmatory factor analysis (CFA) evaluation. A pool of 58 items was created through a literature review and discussions within the research group. The tool’s validity (face, content, construct, convergent, and divergent validity) and reliability (test-retest and internal consistency) were assessed. Results: Qualitative and quantitative methods ensured that the items were clear, relevant, and unambiguous (face validity). All items had an IS above 1.5. Content validity was confirmed through a high content validity ratio (CVR > 0.62) for all items, expert review, and a satisfactory modified Kappa coefficient (K* > 0.75). The EFA identified eight distinct factors [Kaiser-Meyer-Olkin (KMO) = 0.92, Bartlett’s test = 6674.18, P < 0.001] explaining a significant portion of the variance (over 57%). In this step, two items (factor 8: Q1 and Q2) were removed due to cross-loading. The 56-item tool was entered into CFA. The CFA with adjustments [Comparative Fit Index (CFI) = 0.94, Parsimonious Normed Fit Index (PNFI) = 0.67, discrepancy divided by degrees of freedom (CMIN/DF) = 2.22, root mean square error of approximation (RMSEA) = 0.08, and Incremental Fit Index (IFI) = 0.92] established a good model fit. Both convergent and divergent validity were supported by metrics such as average variance extracted (AVE), maximum shared squared variance (MSV), and composite reliability (CR). Cronbach’s alpha and McDonald’s omega were excellent (above 0.80). Test-retest analysis revealed good to moderate external reliability for different factors, indicating that scores remained consistent over time (perceived reward: r = 0.826, n = 30, P < 0.001; fear: r = 0.912, n = 30, P < 0.001; perceived sensitivity: r = 0.923, n = 30, P < 0.001; response cost: r = 0.826, n = 30, P < 0.001; and protection motivation: r = 0.917, n = 30, P < 0.001). Conclusions: This study validated the Persian version of the CCSDT, based on the PMT framework, in individuals aged 50 - 69, confirming its reliability and validity. The tool can help public health practitioners identify barriers to CRC screening and design targeted interventions to improve participation. These findings could contribute to reducing the CRC burden in Iran. Future research should validate the CCSDT in other populations and settings and explore its role in enhancing screening programs.