Red cell distribution width is a potential predictor of early relapse in polymyalgia rheumatica.

Red blood cell distribution width (RDW) has been studied as a prognostic biomarker for different chronic inflammatory diseases. In this paper we aim to evaluate its potential role in the prediction of early relapse in patients affected by polymyalgia rheumatica (PMR). We revised retrospectively clinical records of patients who received a diagnosis of PMR, according to 2012 ACR/EULAR classification criteria, for whom baseline clinical and laboratory data were available. The baseline RDW variation coefficient was correlated to the risk of relapse, in the first 6 months of the disease. We identified 44 patients [females 15 (34.0%)/males 29 (66.0%); median age 80 (72-83)], 9 of whom had an early relapse. These patients showed a larger median RDW than patients who did not relapse [13.7 (13.5-14.9)% vs 13.5 (12.7-14.2)%; p=0.04). The two groups were comparable for all the other clinical and laboratory parameters considered. Interestingly, patients in the higher half of the RDW distribution showed a shorter relapse-free survival (p<0.03). In a stepwise logistic regression, RDW (p=0.01) predicted the risk of relapse at 6 months, while age, gender, CRP, ESR, Hb, MCV and prednisone dose did not fit the model. Our results show that RDW is an independent biomarker of early relapse, making this parameter a potentially promising predictive marker in PMR.

Association between red cell distribution width and response to methotrexate in rheumatoid arthritis.

Red cell distribution width (RDW) is an unconventional biomarker of inflammation. We aimed to explore its role as a predictor of treatment response in rheumatoid arthritis (RA). Eighty-two RA patients (55 females), median age [interquartile range] 63 years [52-69], were selected by scanning the medical records of a rheumatology clinic, to analyze the associations between baseline RDW, disease activity scores and inflammatory markers, as well as the relationship between RDW changes following methotrexate (MTX) and treatment response. The lower the median baseline RDW, the greater were the chances of a positive EULAR response at three months, 13.5% [13.0-14.4] being among those with good response, vs 14.0% [13.2-14.7] and 14.2% [13.5- 16.0] (p=0.009) among those with moderate and poor response, respectively. MTX treatment was followed by a significant RDW increase (p<0.0001). The increase of RDW was greater among patients with good EULAR response, becoming progressively smaller in cases with moderate and poor response (1.0% [0.4-1.4] vs. 0.7 [0.1-2.0] vs. 0.3 [-0.1-0.8]; p=0.03). RDW is a strong predictor of early response to MTX in RA. RDW significantly increases after MTX initiation in parallel to treatment response, suggesting a role as a marker of MTX effectiveness.