This study seeks to estimate clinically significant change in quality of life (QOL) appraisal by comparing changes in appraisal over 6 months of follow-up in people with multiple sclerosis who experienced no change in symptoms versus those with worsening symptoms. This estimation is important for enabling valid interpretation of longitudinal change, both in terms of ensuring the comparison of scores and for response shift estimation.
This is a secondary analysis of longitudinal data (N = 859) of participants in the North American Research Committee on Multiple Sclerosis registry. Patient groupings were characterized on the basis of self-reported symptom change over 1 year of follow-up and compared in terms of their responses to the QOL Appraisal Profile. Bonferroni adjustments reduced the type I error rate, and interpretation was restricted to those comparisons with small or larger effect sizes using Cohen’s criteria.
The Symptoms Unchanged group evidenced more change in Frame of Reference goal delineation themes and Combinatory Algorithm, whereas the Symptoms Worse group evidenced more change in Sampling of Experience and Standards of Comparison items. The group differences were, however, not large or statistically significant in most cases, likely due to being under-powered to detect interaction effects.
Many aspects of appraisal are relatively constant in the context of unchanging and changing symptom experience, but symptom changes led patients to make substantial shifts in what experiences they sample when thinking about their health-related QOL. These underlying cognitive processes may help people to maintain homeostasis in their perceived QOL.