To identify the prevalence of disability in a wide range of life activities and identify factors associated with such disability using the Verbrugge and Jette disablement model as a framework.
Data were from a panel study of 548 individuals with rheumatoid arthritis, interviewed annually by telephone. Valued life activity (VLA) disability was assessed using a 26-item scale rating difficulty in carrying out each activity. Three types of summary measure were calculated: activities unable to perform, activities affected, and mean difficulty. Subscale scores were also calculated, corresponding to obligatory, committed, and discretionary activities, as defined in the disablement model. Disease status measures were examined as predictors of VLA disability using multiple regression analyses.
Half the subjects were unable to do at least one VLA. Approximately 2%, 31.3%, and 40.2% were unable to do at least one obligatory, committed, and discretionary activity, respectively. Almost all (95%) reported at least one VLA affected by rheumatoid arthritis; 68.4%, 91.4%, and 92.5% reported at least one obligatory, committed, and discretionary activity, respectively, affected. Disease status measures were robust predictors of VLA disability, accounting for 22-47% of the variation in VLA disability (with one exception). Adding the health assessment questionnaire (HAQ) to these models increased (p<0.0001) all model R2 values. HAQ score mediated the effects of many disease measures, consistent with the disablement model.
VLA disability was common, with more disability noted in committed and discretionary than obligatory activities. Because VLA disability has been linked to psychological wellbeing in previous studies, identification of factors that may protect against such disability is important.