Inflammation, disease duration, and chronic pain were identified as the main factors underlying fatigue experienced by patients with psoriatic arthritis (PsA), according to a study published in The Journal of Rheumatology.

Despite the high prevalence of fatigue in individuals with PsA, research examining the underlying factors of this phenomenon is scarce.

In this cross-sectional survey conducted between December 2013 and June 2104 in Denmark, 1062 adult patients with PsA were recruited from the national registry system (DANBIO). Study participants were asked to rate their fatigue levels over the previous week on a 0 to 100 visual analog scale (VAS fatigue). Based on VAS fatigue scores, participants were divided into 2 groups: non to mild fatigue (VAS <57) and moderate to severe fatigue (VAS ≥57). There were 520 individuals in the low fatigue group (median age, 53.0 years; 48.7% women; median disease duration, 6.0 years), and 542 in the high fatigue group (median age, 52.0 years; 66.1% women; median disease duration, 5.0 years).

The Pain Detect Questionnaire (PDQ) was used to classify PsA pain as nociceptive (PDQ <13), unclear (PDQ, 13-18), or neuropathic (PDQ >18). A principal component analysis was conducted to identify factors underlying PsA-associated fatigue. Multivariable adjustments were made for age, disease duration, 28-joint counts, C-reactive protein (CRP) level, PDQ score, and VAS global health score.

Three main factors were identified as primary drivers of patient fatigue in PsA: inflammatory factors (eg, elevated CRP, high swollen/tender joint counts, high PDQ score, and poor physician global health assessment) accounted for 31%; older age and longer disease duration contributed 17%; and chronic pain without inflammation (eg, older age, joint counts, PDQ score coupled with low CRP) was responsible for 15%. The chronic pain component was suggestive of structural joint damage or pain centralization.

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Higher levels of fatigue were found to be associated with the 3 components overall (correlation coefficient, 0.39; P <.001), in a clinically relevant manner. Individually, all 3 components were also correlated with fatigue levels (correlation factors: inflammation, 0.73; P <.001; chronic pain, 0.35; P <.001; age/disease duration, 0.06; P =.45).

Study limitations include incomplete baseline data and a risk for selection bias.

“In conclusion, this study showed a strong association between fatigue and clinically important features including inflammation, disease duration, and chronic pain which are relevant to take into account when treating PsA,” noted the authors. “[T]he current study offers new insights into the mechanisms leading to fatigue.”

Funding and Conflicts of Interest Disclosures

This work was supported by a core grant from the Oak Foundation [OCAY-13-309].

Please see original article for conflict of interest information.

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Reference

Skougaard M, Jørgensen TS, Rifbjerg-Madsen S, et al. In psoriatic arthritis fatigue is driven by inflammation, disease duration, and chronic pain: an observational DANBIO registry study [published online July 15, 2019]. J Rheumatol. doi:10.3899/jrheum.181412