We agree with P.J. McDowell and co-workers that the patients whose data are recorded in the UK Severe Asthma Registry (UKSAR) have, on average, more severe asthma than participants in randomised controlled trials (RCTs) of inhaled corticosteroid (ICS)/formoterol maintenance and reliever therapy (MART) 1, 2. However, poor generalisability from RCTs to severe asthma registries is also the case for RCTs of high dose ICS/long-acting β-agonist (LABA) plus short-acting β-agonist (SABA) reliever therapy. There are similar differences in average baseline severity between patients in the UKSAR database and participants in RCTs of high dose versus medium dose ICS/LABA plus SABA therapy, as with those in the MART studies (table 1) 3–13. ICS/formoterol MART is an evidence-based alternative to high dose ICS/LABA in asthma patients at high risk of severe exacerbations; limited generalisability of RCTs to severe asthma registries applies similarly to high dose ICS/LABA therapy as to MART https://bit.ly/4aVFrNH