Oral mucolytic drugs for exacerbations of chronic obstructive pulmonary disease: systematic review.

OBJECTIVE To assess the effects of oral mucolytics in adults with stable chronic bronchitis and chronic obstructive pulmonary disease. DESIGN Systematic review of randomised controlled trials that compared at least two months of regular oral mucolytic drugs with placebo. STUDIES Twenty three randomised controlled trials in outpatients in Europe and United States. MAIN OUTCOME MEASURES Exacerbations, days of illness, lung function, adverse events. RESULTS Compared with placebo, the number of exacerbations was significantly reduced in subjects taking oral mucolytics (weighted mean difference -0.07 per month, 95% confidence interval -0.08 to -0.05, P<0.0001). Based on the annualised rate of exacerbations in the control subjects of 2.7 a year, this is a 29% reduction. The number needed to treat for one subject to have no exacerbation in the study period would be 6. Days of illness also fell (weighted mean difference -0.56, -0.77 to -0.35, P<0.0001). The number of subjects who had no exacerbations in the study period was greater in the mucolytic group (odds ratio 2.22, 95% confidence interval 1.93 to 2.54, P<0.0001). There was no difference in lung function or in adverse events reported between treatments. CONCLUSIONS In chronic bronchitis and chronic obstructive pulmonary disease, treatment with mucolytics is associated with a reduction in acute exacerbations and days of illness. As these drugs have to be taken long term, they could be most useful in patients who have repeated, prolonged, or severe exacerbations of chronic obstructive pulmonary disease.