Fifteen trials (1,046 patients) were included in the analysis. Six of the trials were unpublished.
Erdosteine induced a statistically significant reduction in comparison to placebo or mucolytics in cumulative global efficacy index (-1.02, 95% CI -1.60 to -0.44; n=1,046), cough frequency (-0.19, 95% CI -0.34 to -0.03; n=972), cough intensity (-0.30, 95% CI -0.44 to -0.17; n=496), sputum viscosity (-0.28, 95% CI -0.49 to -0.07; n=812), difficulty to expectorate (-0.24, 95% CI -0.40 to -0.08; n=992) and catarrh ronchi at auscultation (-0.35, 95% CI -0.60 to -0.10; n=469). There no significant reductions for sputum purulence (-0.11, 95% CI -0.28 to 0.07; n=946) and dyspnoea (-0.09, 95% CI -0.24 to 0.07).
Statistically significant heterogeneity was present for all reported outcomes overall and in subgroups based on comparison with mucolytics or placebo with the exception of difficulty to expectorate in comparison to mucolytics. Adverse events (mostly gastrointestinal) were reported by 54 of 529 patients in the erdosteine group and 57 of 517 patients in the comparator group.