The utility of the short Warwick Edinburgh mental wellbeing scale (SWEMWBS) in caregivers: an application of item response theory

Purpose. This study aims to evaluate the effectiveness of the SWEMWBS in assessing the mental well-being of caregivers using the Item Response Theory (IRT) approach. Methods. The Grade Response Model (GRM) from IRT analysis was applied to survey data, estimating discriminant and difficulty parameters at various thresholds. The estimated parameters were examined and presented graphically. Reliability was assessed using Cronbach’s alpha (α), McDonald’s omega (ω), and Intra-Class Correlation for test-retest reliability. Correlations with depression, anxiety, and insomnia were analyzed using multiple linear regression models. Results. The GRM results showed high discriminating parameters (2.17 to 3.67) and nearly evenly distributed difficulty parameters (-2.23 to 1.77). Graphical examinations indicated good performance across the latent trait continuum. Subgroup analyses revealed that caregivers had higher discrimination parameter estimates than non-caregivers. Difficulty parameters varied on the negative latent trait but were higher for non-caregivers on the positive latent trait. The scale demonstrated high internal consistency, with Cronbach’s alpha and McDonald’s omega values of 0.90, and an Intra-Class Correlation of 0.78 with a four-week inter-test interval. Significant negative correlations with depression, anxiety, and insomnia were found after adjusting for demographic variables. Conclusions. The scale exhibits high discriminative power and an adequate response set for assessing a full range of latent traits in both caregivers and non-caregivers, with slightly better performance in caregivers. The SWEMWBS and its derivatives have been validated in specific populations, such as individuals with disabilities. With the global population aging and a significant increase in chronic diseases, the need for informal caregiving has grown substantially. SWEMWBS has been used to measure the mental well-being of informal caregivers, but its validity and utility have not been thoroughly examined. This study evaluates the Chinese version of the scale for its effectiveness in adult caregivers and non-caregivers. It aims to determine the scale’s validity and usefulness in assessing mental well-being. The results indicate that the scale is valid and reliable for both groups, with slightly better performance in caregivers.