Active ageing measurement: UJACAS structure, stability, and the proposed rationale for "ability" and "opportunity" to act as contextual moderators.

The concept of active ageing (AA) emphasises opportunities for health, social participation, and security in old age. The Jyvaskyla University Active Aging Scale (UJACAS) is a key and innovative tool that operationalizes the construct through four components: will to act, ability to act, opportunity to act, and activity. However, the conceptual role of the ability to act and opportunity to act subscales could be further contextualised within an existing behavioural framework. This study analysed the structure of UJACAS through two studies. Study I proposed an Italian translation of the scale and verified the measurement stability by modifying the order of administration of the subscales to analyse the responses related to the activity performed. Study II used a theory-based canonical correlation modelling approach to explore associations between the UJACAS subscales and two external measures assessing physical limitations (WHODAS 2.0) and environmental barriers (ad hoc questionnaire). The order of administration of the subscales did not have a significant impact on response patterns, confirming the stability of the scale's measurement. Multivariate analyses showed significant associations between the UJACAS subscales and external measures, with stronger associations for the opportunity to act subscale than for ability to act. These findings suggest that these two subscales may function as behavioural preconditions of AA, consistent with the COM-B theoretical framework. This perspective can guide refinements in the measurement process and support the development of targeted implementation strategies.