Development and Validation of an Instrument to Measure Intention of Cancer Surveillance Among Patients With Hereditary Colorectal Cancer on the Basis of Theory of Planned Behavior.

Objective: Patients with hereditary colorectal cancer (HCRC) require consistent surveillance for both intestinal and extra-intestinal cancers. This study aims to develop a scale to measure variables associated with the intention of cancer surveillance behavior among patients with HCRC based on the Theory of Planned Behavior.

Methods: The preliminary scale was constructed using direct measures derived from a literature review, and belief-based indirect measures generated through a belief elicitation study involving 23 patients with HCRC. Then a sample of 134 patients was recruited to evaluated the validity and reliability of the scale.

Results: The finalized scale comprises 37 items with 4 subscales. The I-CVI ranged from 0.875 to 1.000, while the S-CVI/Ave for each subscale varied between 0.964 and 1.000. The Cronbach's α for the direct measures of each subscale ranged from 0.819 to 0.940. The intraclass correlation coefficient was between 0.609 and 0.893. Exploratory factor analysis revealed that the direct measures accounted for 80.133% of the variance. Convergent validity was established between the direct measures and the indirect measures (attitudes r = 0.469, P < .001; subjective norms r = 0.374, P < .001; perceived behavioral control r = 0.353, P < .001).

Conclusion: The scale demonstrates adequate construct validity, predictive validity, internal consistency reliability and test-retest reliability, making it a valuable tool for assessing beliefs regarding cancer surveillance in patients with HCRC.

Implications for nursing practice: This newly developed scale will provide critical insights into how intentions influence actual cancer surveillance behavior among patients with HCRC. This understanding will facilitate the design of nursing interventions aimed at enhancing surveillance behaviors and long-term health outcomes.