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Abstract
Background Between 80–90% of patients with systemic lupus erythematosus (SLE) report fatigue to be the single most troublesome and debilitating symptom of their illness.1 Recent studies have found that functional iron deficiency and iron deficiency anaemia have been linked with fatigue and decreased cognitive performance.2 Increased red blood cell distribution width (RDW) is an early indicator of iron deficiency that can be useful in assessing iron stores in patients with SLE who may have an elevated serum ferritin due to underlying inflammation.
Objectives To investigate the relationship between early iron deficiency (measured by RDW) and fatigue in adolescents and young adults with SLE.
Methods Adolescent and young adult patients with SLE were recruited prospectively between November 2016 and January 2017. All patients were asked to complete the Functional Assessment of Chronic Fatigue Illness Therapy (FACIT) Fatigue Scale v4, in which a numerical score between 0–52 is generated. Lower scores indicate more fatigue. Standard measures of lupus disease activity including Erythrocyte Sedimentation Rate (ESR), C-Reactive Protein (CRP), Complement C3 levels, anti-double stranded DNA binding (anti-dsDNA) and SLEDAI were recorded. Haemoglobin (Hb) and RDW were also measured. Anaemia was defined by World Health Organisation criteria (male Hb <130g/L and female Hb <120g/L). Non-parametric analysis was performed using Spearman's rank with a p-value <0.05 felt to be significant.
Results 33 patients aged between 16.7 and 27.5 years (median age 20) were included. 85% of the patients were female. Their FACIT scores were lower than those published for healthy individuals of the same age group - median 24, IQR 22–44 for SLE vs median 43, IQR 35–48 for healthy. There was no statistically significant correlation between FACIT Fatigue score and SLEDAI (p=0.92), anti-dsDNA (p=0.36), C3 levels (p=0.37), ESR (p=0.30) or CRP (p=0.85). Interestingly a statistically significant negative correlation between FACIT Fatigue score and RDW was observed (p=0.012; r=-0.43). A correlation between FACIT Fatigue score and Hb was noted although this was not statistically significant (p=0.079). 12 of the 33 patients were found to be anaemic (11 female, 1 male). Analysis of the sub-group of 21 non-anaemic patients found FACIT Fatigue Score and RDW continue to show a statistically significant association (p=0.026; r=-0.49).
Conclusions Fatigue is a common and debilitating symptom described by young patients with SLE. Standard serological and clinical markers of disease activity did not correlate with the burden of fatigue. Increased RDW has been shown for the first time to correlate with increased fatigue in patients with lupus, suggesting that iron deficiency may play a significant role in the manifestation of this troublesome symptom. A trial of therapeutic iron infusions in the treatment of fatigue in SLE is planned.
References
Tench CM, McCurdie I, White PD, D'Cruz DP. The prevalence and associations of fatigue in systemic lupus erythematosus. Rheumatology 2000;39:1249–1254.
Greig AJ, Patterson AJ, Collins CE, Chalmers KA. Iron deficiency, cognition, mental health and fatigue in women of childbearing age: a systematic review. J Nutr Sci 2013;29;2:e14.
References
Disclosure of Interest None declared