Abstract
AIM: To validate a modified version of the Intrinsic Motivation Inventory (IMI)-the IMI-HeartLife-adapted for heart-healthy lifestyle behaviours in community-dwelling adults without a history of cardiovascular disease. While the original IMI has been validated in contexts such as competitive sports and education, its use in healthcare-particularly for cardiovascular disease prevention-has been limited. DESIGN: A validation study addressing content and construct validity and reliability. METHODS: The IMI-HeartLife was refined through three phases: (1) conceptualisation and item pool generation, (2) evaluation of content and face validity and (3) psychometric evaluation. As part of the psychometric evaluation, two established instruments were employed to assess the discriminant and convergent validity of the IMI-HeartLife scale. RESULTS: A total of 703 community-dwelling adults were recruited and randomly assigned to two subsamples for exploratory (n = 352) and confirmatory (n = 351) factor analyses. From the initial 32 items drawn from five original IMI subscales, 16 were retained. A three-factor structure-Interest/Enjoyment, Choice/Value/Usefulness and Competence/Effort-was supported (CMIN/DF = 3.43, SRMR = 0.06, RMSEA = 0.08, CFI = 0.95, TLI = 0.94). Discriminant and convergent validity of the IMI-HeartLife were confirmed, and internal consistency and test-retest reliability were acceptable. CONCLUSIONS: The 16-item IMI-HeartLife demonstrated good validity and reliability as a measure of intrinsic motivation to promote heart-healthy lifestyle in cardiovascular disease prevention. IMPLICATIONS FOR THE PROFESSION: In community and primary care settings, nurses are well positioned to assess intrinsic motivation as a core cognitive construct and to deliver personalised interventions that promote heart-healthy lifestyle behaviours in the context of cardiovascular disease prevention. Within this framework, the IMI-HeartLife may serve as a valuable instrument for assessing intrinsic motivation and guiding individualised nursing strategies. REPORTING METHOD: COSMIN reporting guideline for studies on measurement properties of patient-reported outcome measures (PROM): version 2.0. PUBLIC ENGAGEMENT: The content analysis was conducted in collaboration with an interdisciplinary user group including eight healthcare professionals.