An Investigation of Construct Validity and Responsiveness of the Danish ICECAP-A

BackgroundThis study aimed to provide the first assessment of construct validity of ICECAP-A in patients with cardiovascular disease, chronic obstructive pulmonary disease and diabetes, and to assess the responsiveness of the measure in this group. MethodData were provided from patients attending rehabilitation in the municipality of Aalborg, Denmark, from March 2018 to March 2019. Patients answered a questionnaire from the healthcare centre and the ICECAP-A at baseline and 12 weeks follow-up. To assess construct validity, a priori hypotheses were developed. Based on these hypotheses, associations between sociodemographic characteristics, ‘general health’, a freedom dimension, and ICECAP-A were analysed through chi-squared tests and Spearman rank correlations for categorical and ordinal variables, respectively. To investigate responsiveness, the anchor-based method was used. Patients were divided into improved, worsened or no change, based on changes between baseline and follow-up on the anchor measures (‘general health’ and ‘freedom’). To quantify responsiveness, both the weighted and un-weighted ICECAP-A scores’ effect sizes, standardised response means and t-tests were used. Findings were explored across different age groups.ResultOf all the hypothesised associations, 16 of 26 (62%) were in the expected direction. The expected relationships were found between ICECAP-A scores and general health and freedom to do things. ICECAP-A was responsive in terms of capturing the effects on general health and the freedom to do things. Differences were found across age groups, with greater responsiveness to change in those aged under 65 years. The item-by-item analysis showed that capability was mainly driven by stability and autonomy.ConclusionThis study has shown that the Danish ICECAP-A is a valid and responsive measure of the effects of an exercise and education-based rehabilitation programme.