Objective
To compare illness perceptions among patients with different forms of vasculitis, identify risk factors for negative illness perceptions, and determine the association between illness perceptions and fatigue.
Methods
Participants were recruited from an online registry in vasculitis to complete the revised Illness Perception Questionnaire (IPQ-R). Mean scores on each IPQ-R dimension were compared across types of vasculitis. Cluster analysis and stepwise regression identified predictors of negative illness perception. Fatigue was measured using the general subscale of the Multidimensional Fatigue Inventory (MFI). Patient-reported measures of disease activity and IPQ-R dimensions were assessed in relation to MFI scores using linear regression in sequential, additive models with model-fit comparisons.
Results
692 participants with 9 forms of vasculitis completed the IPQ-R. For 6 out of 8 IPQ-R dimensions, there were no significant differences in mean scores between the different vasculitides. Scores in identity and cyclical dimensions were significantly higher in Behçet’s disease compared to other types of vasculitis (13.5 vs 10.7; 4.0 vs 3.2, p<0.05). Younger age (OR=1.04; 95%CI 1.02–1.06), depression (OR=4.94; 95%CI 2.90–8.41), active disease status (OR=2.05; 95%CI 1.27–3.29), and poor overall health (OR=3.92; 95%CI 0.88–17.56) were associated with negative illness perceptions. Sequential models demonstrated that IPQ-R dimensions explained an equivalent proportion of variability in fatigue scores compared to measures of disease activity.
Conclusion
Illness perceptions are similar across different types of vasculitis, and younger age is a risk factor for negative illness perceptions. Illness perceptions explain differences in fatigue scores beyond what can be explained by measures of disease activity.