The impact of smoking status on the efficacy of inhaled corticosteroids in chronic obstructive pulmonary disease: a systematic review

Objectives: Inhaled corticosteroids (ICS) reduce exacerbation rates and the decline in lung function in people with chronic obstructive pulmonary disease (COPD). There is evidence that smoking causes ‘steroid resistance’ and thus reduces the effect of ICS. This systematic review aimed to investigate the effect of smoking on efficacy of ICS in COPD in terms of lung function and exacerbation rates.
Design: Systematic review
Data Sources: An electronic database search of PubMed, Ovid Medline, Ovid Embase and Cochrane Library (Jan 2000-Jan 2020).
Eligibility criteria: Fully published RCTs, in the English language, evaluating the use of ICS in COPD adults that stratified the participants by smoking status. Trials that included participants with asthma, lung cancer and pneumonia were excluded. The primary outcome measures were changes in lung function and yearly exacerbation rates.
Data extraction and synthesis: Two independent reviewers extracted data and assessed risk of bias using the Coc...