RESEARCH - Is fatigue an inflammatory variable in RA? Analyses of fatigue in RA, OA, and fibromyalgia

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J Rheumatol. 2009 Nov 16.

Is Fatigue an Inflammatory Variable in Rheumatoid Arthritis (RA)?

Analyses of Fatigue in RA, Osteoarthritis, and Fibromyalgia.

Bergman MJ, Shahouri SS, Shaver TS, JD, Weidensaul DN, Busch

RE, Wang S, Wolfe F.

From Drexel University College of Medicine, Philadelphia,

Pennsylvania; Arthritis and Rheumatology Clinics of Kansas; University

of Kansas School of Medicine; and the National Data Bank for Rheumatic

Diseases, Wichita, Kansas, USA.

OBJECTIVE: To investigate whether fatigue is an inflammatory

(rheumatoid arthritis; RA) variable, the contributions of RA variables

to fatigue, and the levels of fatigue in RA compared with

osteoarthritis (OA) and fibromyalgia (FM).

METHODS: We studied 2096 RA patients, 1440 with OA, and 1073 with FM

in a clinical setting, and 14,607 RA, 3173 OA, and 2487 patients with

FM in survey research. We partitioned variables into inflammatory and

noninflammatory factors and examined variable contribution to fatigue

(0-10 visual analog scale).

RESULTS: Factor analysis identified Disease Activity Score-28 (DAS28)

and swollen (SJC) and tender joint count (TJC) as a

physician-inflammation factor, and patient global assessment, pain,

Health Assessment Questionnaire, and fatigue as patient components.

Fatigue demonstrated weak correlations with erythrocyte sedimentation

rate (ESR; r = 0.071) and SJC (r = 0.112), weak to fair correlations

with TJC (r = 0.294), physician global assessment of RA activity (r =

0.384), and DAS28 (r = 0.399), but strong correlation with patient

global assessment of severity (r = 0.567). In hierarchical regression

analysis, patient global explained 43.1% of DAS28 fatigue variance;

when SJC, TJC, and ESR were entered, the explained variance increased

to 43.7%. In reverse order, SJC, TJC, and ESR explained 9.2% of the

variance, but explained variance increased to 43.7% when patient

global was added. The mean clinic fatigue scores were RA 4.9, OA 4.8,

FM 7.6; mean survey scores were RA 4.5, OA 4.4, FM 6.3. Adjusted for

age and sex, RA and OA fatigue scores were not significantly

different.

CONCLUSION: Inflammatory components of the DAS28 contribute minimally

to fatigue. RA and OA fatigue levels do not differ. Fatigue is not an

inflammatory variable and has no unique association with RA or RA

therapy.

PMID: 19918042

http://www.ncbi.nlm.nih.gov/pubmed/19918042

Not an MD