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.
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).
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.
Asthma may be a risk factor for the development of MDS/CMML.