Background In cross-sectional studies it was found that psychosocial factors, pain and daily functioning, rather than inflammation, are associated with fatigue severity in rheumatoid arthritis (RA). However, it is unknown which factors predict the course of fatigue over a longer period.
Objectives The objective of this longitudinal study was 1) to investigate the change of fatigue over time and 2) to identify which factors predict fatigue severity over time in RA patients.
Methods A prospective cohort study of one year duration was performed with monthly assessments of fatigue in consecutive patients with established RA. Patients with at least 3 measurements of fatigue over 12 months were included in the analysis (n=212). Fatigue was assessed with the Checklist Individual Strength (CIS). Disease-specific measures and a comprehensive set of psychosocial factors were measured at baseline. Baseline differences between severely and non-severely fatigued patients over time (cut point of 35 in mean CIS-fatigue score) were analyzed with a chi-square test, unpaired t-test or a Mann-Whitney U test, as appropriate. Backward multivariable chunk-wise linear regression analysis with 9 blocks was performed to identify which factors are relevant for fatigue severity over time. The blocks were sets of patient characteristics, disease related variables, pain, disability, psychological health, personality, cognitions and coping, social support and social functioning, sleep quality.
Results The mean (SD) baseline CIS fatigue score was 31.0 (12.5), with 40.1% having severe fatigue. Within patients, fatigue levels appeared to fluctuate around a stable level (p=0.20). The multivariate linear regression analysis showed that age, gender, pain, physical functioning, optimism, self-esteem, self-efficacy, coping strategies like worrying and magnification of fatigue, social functioning and sleep quality are significant independent predictors for CIS-fatigue over time, with 56% of variance explained. Descriptive statistics are shown in table 1.
Conclusions In RA patients, fatigue levels are quite stable over time. Having 12 months of severe fatigue is predicted by higher levels of pain and disability, lower self-esteem, lower self-efficacy and less productive coping styles, less well social functioning and less quality of sleep.
Disclosure of Interest None Declared