Hyperthyroidism in patients with asthma

We read with great interest the study by Gau et al1 on the risk of hyperthyroidism in patients with asthma. In this retrospective cohort study using an insurance claims database, the authors hypothesized that patients with asthma had a higher risk for hyperthyroidism. To augment the findings, several recommendations on covariates that could be included in the study may be adopted.