• chronic obstructive pulmonary disease
• inhaled corticosteroids
• ethics
• placebo controlled studies

The meta-analysis by Sutherland et al¹ of the effect of inhaled corticosteroids on the progression of airflow limitation in patients with chronic obstructive pulmonary disease (COPD) found a small improvement in forced expiratory volume in 1 second (FEV₁) of −7.7 ml/year (95% CI −14.2 to −1.3) which is similar to the results of the meta-analysis performed by Highland et al² (−5 ml/year (95% CI −11.2 to 1.2)) using a very similar data set. The meta-analyses employed slightly different study selection criteria and analytical techniques, and questioned the clinical significance of such small differences in FEV₁. The selected primary studies suffered from potential drop-out bias and significant selection bias, in that almost all of the studies subjected to these meta-analyses excluded patients with a bronchodilator response.² Studies of asthma and COPD as separate entities are limited because asthma and COPD (observed in cross section) represent a continuum,³ and the small number of available prospective observations indicates that asthma and COPD are sometimes different clinical manifestations of the same underlying aetiology evolving over time.⁴ Given all the uncertainties, questions and limitations, Highland et al² concluded (correctly in my opinion) that “additional studies are needed …