Association between chronic kidney disease and the risk of myelodysplastic syndromes: A large claims database study in Japan

To the Editor, Chronic kidney disease (CKD) is commonly associated with renal anaemia, 1 however, some patients with CKD develop cytopenias, raising concern for bone marrow disorders.Myelodysplastic syndromes (MDS) are clonal haematopoietic disorders characterized by ineffective haematopoiesis, peripheral cytopenias and a risk of progression to leukaemia.2 Although environmental exposures have been implicated, the aetiology of MDS remains incompletely understood. 2 The incidence of MDS increases with age, making age-related clonal haematopoiesis an increasingly recognized potential precursor state that may contribute to MDS development.3 CKD promotes chronic inflammation, oxidative stress and uremic toxins accumulation, which may impair haematopoiesis.4 Emerging evidence has related clonal haematopoiesis to CKD, 5 providing a possible link between CKD and MDS.Although dialysis-dependent kidney failure has been associated with MDS, 6 it remains unclear whether moderate-to-severe pre-dialysis CKD confers an increased risk of incident MDS.Therefore, we aimed to evaluate the association between CKD and incident MDS.This study used DeSC Healthcare claims and annual health checkup data from April 2014 to December 2024.This database included approximately 18 million people in 2025.7 DeSC Healthcare Inc. anonymized all processed information under Japan's Personal Information Protection Law; therefore, individual consent and ethics committee approval were not required according to the ethical guidelines for clinical research in Japan.Figure S1 presents an overview of the study design.Figure S2 presents the study flow diagram.Individuals meeting any of the following criteria were excluded: (1) a baseline diagnosis of MDS (defined by the International Classification of Diseases 10th Revision (ICD-10) code D46); (2) baseline end-stage kidney disease, corresponding to CKD G5 or G5D; or (3) insufficient or unusable information on deaths.Kidney function was assessed using the estimated glomerular filtration rate (eGFR), calculated from serum creatinine measurements at annual outpatient health checkups using the Japanese equation.In accordance with the Kidney Disease: Improving Global Outcomes concept of chronicity,