Cigarette Smoking Impairs the Therapeutic Response to Oral Corticosteroids in Chronic Asthma

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Abstract
The study was designed to assess the effect of cigarette smoking on the therapeutic response to oral corticosteroids in chronic stable asthma. We performed a randomized, placebo-controlled, crossover study with prednisolone (40 mg daily) or placebo for 2 weeks in smokers with asthma, ex-smokers with asthma, and never-smokers with asthma. All subjects had reversibility in FEV1 after nebulized albuterol of 15% or more and a mean postbronchodilator FEV1% predicted of more than 80%. Efficacy was assessed using FEV1, daily PEF, and an asthma control score. There was a significant improvement after oral prednisolone compared with placebo in FEV1, ml (mean difference, 237; 95% confidence intervals, 43, 231; p = 0.019), morning PEF L/m (mean difference, 36.8; 95% confidence intervals (CI), 11, 62; p = 0.006), and asthma control score (mean difference, -0.72; 95% CI, -1.2, -0.3; p = 0.004) in never-smokers with asthma but no change in smokers with asthma (mean differences of 47, 6.5, and -0.05 with p values of 0.605, 0.47, and 0.865, respectively). Ex-smokers with asthma had a significant improvement in morning and night PEF (mean difference, 29.1; CI, 2.3, 56; p = 0.04 and 52.4; CI, 26, 79; p = 0.003, respectively), but not in FEV1 or asthma control score. We conclude that active smoking impairs the efficacy of short-term oral corticosteroid treatment in chronic asthma.