Fatigue in ankylosing spondylitis: treatment should focus on pain management.

OBJECTIVES: Fatigue is an important symptom associated with ankylosing spondylitis (AS). This study examines patients' perspectives and clinical associations of fatigue to help inform potential strategies to alleviate fatigue in AS.
METHODS: A mixed methods approach was taken to examine fatigue in a cohort of people with AS. Fatigue levels were evaluated from 3 consecutive monthly questionnaires. Open-ended questions on fatigue were analyzed using thematic analysis and logistic regression was used to examine quantitative data. In addition, fatigue levels were examined before and after treatment with anti-tumor necrosis factor (TNF) compared to nontreated controls.
RESULTS: Three hundred forty-eight of 385 participants completed a fatigue questionnaire. Fatigue was reported to have significant physical, social, and psychological effects. A third of the participants reported that there was nothing they could do to reduce their fatigue, whereas other participants reported that medication, exercise, and resting helped. The main factor associated with fatigue was pain [β-coefficient: 0.74 (95% CI: 0.66 to 0.81)], whereas depression was much less strongly associated. However, these factors only explained 40% of the variation in fatigue levels. Starting anti-TNF therapy reduced fatigue and pain levels compared to the period of time before taking anti-TNF [difference: 14.4 (95% CI: 5.3 to 23.5) on a scale of 0-100] and this reduction was not seen in controls over the same period.
CONCLUSIONS: Fatigue is not strongly associated with anxiety, motivation, and depression; instead the factor most associated with fatigue is pain. This suggests that in addition to treatments to reduce disease activity, strategies for alleviating fatigue in AS should focus on pain management techniques and actively treating inflammation.