Improved factor structure for self-efficacy scales for children with JIA (CASE) and their parents (PASE).

Objective: Self-efficacy is an important factor in helping children to cope with a chronic disease. In order to study it, we have to be able to develop a valid and reliable scale. We validated and further developed the CASE (Children's Arthritis Self-Efficacy) and PASE (Parent's Arthritis Self-Efficacy) scales in a Finnish juvenile idiopathic arthritis (JIA) patient and parent population.

Methods: One hundred and twenty JIA children and their parents completed the CASE and PASE assessments, respectively. Exploratory Factor Analysis (EFA) applying the Principal Axis Factoring method was conducted and extended by the use of Confirmatory Factor Analysis (CFA) to allow a theory-driven approach to determine the latent dimensions for both CASE and PASE scales. Construct validity was analysed by measuring the extent to which the CASE and PASE variables correlated with variables of children's and parents' depression scales and with the clinical parameters of the child in a way that can be explained theoretically.

Results: A two-factor solution in PASE corresponding to Barlow's factor solution did not fit the sample of Finnish parents. Instead, a three-factor model similar to that of the CASE scale fitted the data for the PASE scale with self-efficacy in somatic symptoms and psychological and social functioning as subscales. Construct validity was confirmed for both scales.

Conclusion: The refined three-factor structure of the PASE scale and the slightly modified three-dimensional CASE scale were found to be robust scales enabling disease-specific analysis of somatic, psychological and social self-efficacy and comparisons between the patients and parents.