Explanatory factors and predictors of fatigue in persons with rheumatoid arthritis: A longitudinal study.
OBJECTIVE
To investigate the impact of disease-related aspects on long-term variations in fatigue in persons with rheumatoid arthritis.


METHODS
Observational longitudinal study.


METHODS
Sixty-five persons with rheumatoid arthritis, age range 20-65 years, were invited to a clinical examination at 4 time-points during the 4 seasons. Outcome measures were: general fatigue rated on visual analogue scale (0-100) and aspects of fatigue assessed by the Bristol Rheumatoid Arthritis Fatigue Multidimensional Questionnaire. Disease-related variables were: disease activity (erythrocyte sedimentation rate), pain threshold (pressure algometer), physical capacity (six-minute walk test), pain (visual analogue scale (0-100)), depressive mood (Hospital Anxiety and Depression scale, depression subscale), personal factors (age, sex, body mass index) and season. Multivariable regression analysis, linear mixed effects models were applied.


RESULTS
The strongest explanatory factors for all fatigue outcomes, when recorded at the same time-point as fatigue, were pain threshold and depressive mood. Self-reported pain was an explanatory factor for physical aspects of fatigue and body mass index contributed to explaining the consequences of fatigue on everyday living. For predicting later fatigue pain threshold and depressive mood were the strongest predictors.


CONCLUSIONS
Pain threshold and depressive mood were the most important factors for fatigue in persons with rheumatoid arthritis.
Department of Rheumatology and Inflammation Research, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Box 480, SE-405 30 Gothenburg, Sweden. caroline.feldthusen@vgregion.se.
Caroline
C
Feldthusen
Anna
A
Grimby-Ekman
Helena
H
Forsblad-d'Elia
Lennart
L
Jacobsson
Kaisa
K
Mannerkorpi
D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000150:complications*; D003863:Depression / Q000150:complications; D005080:Exercise Test / Q000379:methods; D005221:Fatigue / Q000209:etiology*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000150:complications; D010147:Pain Measurement / Q000379:methods; D017288:Pain Threshold / Q000502:physiology; D012044:Regression Analysis; D012307:Risk Factors; D057566:Self Report; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D055815:Young Adult