Assessment of fatigue in the management of patients with ankylosing spondylitis

Researchers writing in Rheumatology have proposed that fatigue is an independent factor in the quality of life of ankylosing spondylitis patients.Dernis-Labous et al identify that pain, stiffness, functional impairment, range of motion and quality of life are the main conventional domains used in studies evaluating ankylosing spondylitis (AS). However, the researchers comment that fatigue has been reported as "the major complaint" of AS patients. To evaluate fatigue as a potential independent domain in comparison with the "conventional" ones and to evaluate the sensitivity to change after non-steroidal anti-inflammatory drug (NSAID) therapy the current study has been conducted.In their investigation the researchers identified and classified patients according to the modified New York criteria as having painful AS. The following variables were recorded at baseline and after six weeks of therapy (either placebo or NSAIDs): pain (VAS), function (Bath Ankylosing Spondylitis Functional Index), patient's global assessment (VAS), inflammation (night pain), morning stiffness, metrology (Schober test, finger-to-floor) and fatigue using 0-100 VAS scale.Analysis consisted of (i) the prevalence of fatigue (VAS value of at least 50 mm), (ii) the independence of the information evaluated using a regression model, and (iii) the sensitivity to change, by calculating the standardised response mean (mean change/S.D. change) (SRM) between placebo and NSAID group.According to their findings, fatigue was considered important in 401 patients (out of 639: 63%). The information provided by the variables "pain", "function" and "global assessment" was reported to explain only 44% of the variability of the "fatigue" parameter. Similar analyses considering "pain" on the one hand and "function" on the other hand as the dependent variables showed an R2 value of 34 and 60%, respectively. The NSAID treatment effect (SRM) was identified to be higher for the variables "pain" and "function" (0.76 and 0.71, respectively) than for "fatigue" (0.34).In their commentary Dernis-Labous et al propose that fatigue should be considered as an "independent domain to be systematically evaluated in AS patients" and that conventional therapy such as NSAIDs have a lower effect on this domain than on pain or functional impairment.Reference...