Methotrexate therapy impacts on red cell distribution width and its predictive value for cardiovascular events in patients with rheumatoid arthritis

Background Methotrexate (MTX) is well known to affect folic acid metabolism, so MTX treatment can result in alterations of mean corpuscular volume (MCV), which may impact on red cell distribution width (RDW), as MCV levels feed into RDW calculation. We thus questioned whether RDW levels and subsequently its diagnostic utility in RA subjects, as reported before, are influenced by ongoing MTX therapy.We assessed the impact of disease modifying drug (DMARD) treatment, especially MTX, on RDW and evaluated their influence on the predictive value of RDW for cardiovascular (CV) events in patients with rheumatoid arthritis (RA). As far as we know, this is the first study evaluating the influence of MTX on RDW.Methods Medical treatment, disease activity, laboratory parameters and history of CV events were retrospectively analysed in 385 RA patients at disease onset and at last follow up at our clinic. Additionally, in patients with CV event, data were recorded at last follow up prior the CV event.Results Disease parameters and laboratory findings associated with a serious vascular event were older age (p p = 0,002) and a higher RDW at diagnosis (p = 0,025). No differences in RDW levels became evident with any other treatment regimen beside MTX. MTX treated patients had significantly higher RDW compared to subjects without this drug (p Conclusion MTX impacts on RDW and might therefor reduce its prognostic value for CV events in patients taking MTX, whereas an increased RDW at diagnosis remains an early risk predictor for myocardial infarction and stroke in RA patients.