Asthma and risk of myelodysplastic syndromes: a population-based cohort study

BACKGROUND: Risk factors for the development of myelodysplastic syndromes (MDS) include age, exposure to ionising radiation, and cytotoxic drug treatment. Recently, asthma also has been suggested as a risk factor for MDS. METHODS: We undertook this nationwide population-based cohort study on patients with a first-time hospital-based asthma diagnosis during 2002–2013 and followed them for the development of MDS/chronic myelomonocytic leukaemia (CMML). RESULTS: We identified 75 995 patients with incident asthma and no previous MDS/CMML diagnosis. Seventy-eight patients subsequently developed MDS and nine patients developed CMML during 402 892 person-years. The cumulative risks of developing MDS/CMML among asthma patients were 0.02% (95% CI: 0.01–0.04%) and 0.07% (95% CI: 0.05–0.09%) during the first year and the first five years of follow-up, respectively. The standardised incidence ratio of MDS/CMML among asthma patients overall was 1.6 (95% CI: 1.3–2.0) with little variation across subgroups. CONCLUSIONS: Asthma may be a risk factor for the development of MDS/CMML.