Background Functional disability and fatigue are important consequences of systemic sclerosis (SSc), but little is known about the course over time.
Objectives The aim of this study was to identify and characterize homogeneous subgroups with distinct 3-year trajectories of disability and fatigue.
Methods Patients with SSc undergoing treatment in the Sint Maartenskliniek or Radboud University Medical Center Nijmegen in the Netherlands completed sets of questionnaires every 6 months for 3 years. Functional disability was assessed using the Health Assessment Questionnaire-Disability Index (HAQ-DI). Fatigue was assessed using the SF-36 Vitality subscale. Longitudinal trajectories were identified using latent class growth analyses (LCGA) and baseline patient characteristics were compared across classes using multivariable logistic regression.
Results In total, 279 patients were invited to participate in the cohort study, of whom 215 completed the baseline questionnaire (response rate 77.1%). At baseline, the participants had mean age of 56.4 (SD=12.0) years. The majority (67.9%) were women, the mean disease duration was 9.2 (SD=8.0) years, and 75.1% of participants had limited SSc. LCGA identified two classes for disability and two classes for fatigue. For disability, we found a “stable-low” group (n=133) with low baseline HAQ-DI scores (mean = 0.48) and slight, but statistically non-significant deterioration over time (increase in HAQ-DI score of 0.01 per 6 months), and a “stable-high” group (n=82) with high baseline disability scores (mean = 1.63) and also slight, statistically non-significant deterioration over time (increase in HAQ-DI score of 0.01 per 6 months). Patients in the stable-high disability group were more likely to be female, have higher fatigue, more helplessness, and less emotion-focused coping. For fatigue, we found a “stable-moderate” group (n=99) with moderate baseline SF-36 Vitality scores (mean = 53.9) and slight, but statistically non-significant deterioration over time (decrease in Vitality score of 0.23 per 6 months, indicating more fatigue), and a “stable-severe” group (n=116) with high baseline fatigue (mean = 39.8) and also slight, statistically non-significant worsening of fatigue over time (decrease in Vitality score of 0.15 per 6 months). Patients in the stable-severe fatigue group were more likely to be female, report more impact of lung involvement, and less acceptance. One-third of the patients (n=66) belonged to the high disability and high fatigue groups. There was a statistically significant association between the disability subgroups and the fatigue subgroups (p<0.01).
Conclusions Our results suggest that limitations in physical functioning and fatigue are relatively stable consequences of the disease over time. More than half of the patients with SSc in our sample are relatively little affected in daily functioning, whereas the vast majority of patients are at least moderately impacted by fatigue. In addition, our findings imply that psychosocial factors as coping could be considered as targets for treatment in particular in those patients who experience severe limitations in daily functioning and high levels of fatigue.
Disclosure of Interest None declared