We agree with Brian Lipworth and colleagues that multiple factors can affect an individual’s likelihood of developing adrenal suppression during corticosteroid use—we assessed these factors in our previous paper. 1 The issue of airway calibre is relevant to drug deposition and exposure; however, differences exist between the cited cohort2 and ours. The cited cohort was made up of 11 patients with asthma, mean age 45 years, with an FEV11 (% predicted) of 54%. 2 Our discovery cohort included 499 children, mean age 11· 6 years, with an FEV1 (% predicted) of 88%. 1 Our cohort represents increased respiratory function with a corresponding increase in lung deposition. In our COPD val idation cohort, a smaller effect size was noted, which could be related to many factors including increased age, comorbidities, and potentially decreased exposure, as suggested by Lipworth and colleagues. Despite these differences, 22% of our patients with COPD showed biochemical suppression. 3 Pharmacology of the drug also plays a part, however, in contrast to the systematic review by Lipworth, 4 the prevalence of adrenal suppression did not increase with fluticasone in our study. 1 This difference could be because we also included oral (rescue or maintenance asthma therapy), and intranasal (hay fever) corticosteroid use in our analysis to obtain a figure for the overall steroid burden. However, we do completely agree with Lipworth and colleagues that the safest dose of corticosteroid is the lowest effective maintenance dose for the patient, whatever personalisation of therapy is being considered.