Through a glass darkly: inhaled corticosteroids, airway inflammation and COPD

It is 18 years since I last used the famous biblical phrase “through a glass darkly” to describe our uncertainties about the use of inhaled corticosteroids (ICS) in chronic obstructive pulmonary disease (COPD) patients [1]. Subsequently, an enormous amount of research has been undertaken, which has clarified the role of ICS in clinical management [2]. There is general agreement that these drugs produce small improvements in lung function but that their main clinical benefit is to reduce exacerbation frequency, especially for events treated with oral corticosteroids [3]. The impact on COPD mortality of adding ICS to long-acting inhaled bronchodilators remains famously controversial, as does the potential of ICS to reduce the rate of decline of forced expiratory volume in 1 s (FEV1), the topic of my original editorial [1]. Recent data suggest that a small reduction in rate of decline may occur with ICS use [4], in keeping with meta-analysed data from previous studies [5]. The most important development has been the proposal that ICS are only beneficial in individuals with high normal blood eosinophil counts [6], although the threshold value to identify such an effect may reflect the level of background bronchodilator treatment [7]. ICS can reduce inflammation in COPD but this effect ceases after drug discontinuation; clinical effects are unclear http://ow.ly/JgwT306sFn2