Validation of the self-management ability scale (SMAS) and development and validation of a shorter scale (SMAS-S) among older patients shortly after hospitalisation

Background: The 30-item Self-Management Ability Scale (SMAS) measures self-management abilities (SMA). Objectives of this study were to (1) validate the SMAS among older people shortly after hospitalisation and (2) shorten the SMAS while maintaining adequate validity and reliability. Methods: Our study was conducted among older individuals (>= 65) who had recently been discharged from a hospital. Three months after hospital admission, 296/456 patients (65% response) were interviewed in their homes. We tested the instrument by means of structural equation modelling, and examined its validity and reliability. In addition, we tested internal consistency of the SMAS and SMAS-S among a study sample of patients at risk for cardiovascular diseases. Results: After eliminating 12 items, the confirmatory factor analyses revealed good indices of fit with the resulting 18-item SMAS (SMAS-S). To estimate construct validity of the instrument, we looked at correlations between SMAS subscale scores and overall well-being scores as measured by Social Product Function (SPF-IL) and Cantril's ladder. All SMAS subscales of the original and short version significantly correlated with SPF-IL scores (all at p <= 0.001) and Cantril's ladder (for the cognitive well-being subscale p <= 0.01; all other subscales at p <= 0.001). The findings indicated validity. Analyses of the SMAS and SMAS-S in the sample of patients at risk for cardiovascular diseases showed that both instruments are reliable. Conclusions: The psychometric properties of both the SMAS and SMAS-S are good. The SMAS-S is a promising alternate instrument to evaluate self-management abilities.