Development and validation of the Sedentary Behavior Interruption Questionnaire (SB-IQ) for Assessing Behavioral Determinants in Older Adults Requiring Long-Term Care: a cross-sectional study

Background: Older adults requiring long-term care often spend prolonged time in sedentary behavior. Interrupting SB requires assessing the behavioral determinants that support or hinder SB interruptions, but no dedicated instrument is available. This study aimed to develop the Sedentary Behavior Interruption Questionnaire (SB-IQ) and examine its structural and concurrent validity. Methods: Items were generated based on the Theoretical Domains Framework to create an 83-item prototype mapped to the Capability, Opportunity, Motivation, and Behavior system. The prototype was refined through expert review and a three-round Delphi process, yielding a 40-item, content-valid second version. Structural validity was assessed via Rasch analysis in older adults requiring long-term care (n = 129). Concurrent validity was examined in a subsample with accelerometer-measured SB (n = 57) by computing Spearman correlations between SB-IQ domain scores and ≥60-minute sedentary bouts. Results: Rasch analysis indicated that the Motivation domain was not unidimensional; items were reclassified into four domains via exploratory factor analysis, and then reevaluated. The final SB-IQ comprised 28 items across six domains: Capability (5), Opportunity (8), Beliefs about consequences (3), Goals (4), Beliefs about capabilities (5), and Behavioral regulation (3). All domains met unidimensionality and fit criteria. Significant negative correlations with sedentary bouts were seen between Behavioral regulation (rho = –0.349) and Beliefs about capabilities (rho = –0.348). Conclusions: The final SB-IQ was established after structural validation. Its associations with objectively measured sedentary bouts support concurrent validity. The SB-IQ may help clinicians design individualized strategies and identify the behavioral determinants of interruptions in prolonged SB in older adults requiring long-term care.