Induced sputum is a reproducible method to assess airway inflammation in asthma

To evaluate the reproducibility of induced sputum analysis, and to estimate the sample size required to obtained reliable results, sputum was induced by hypertonic saline inhalation in 29 asthmatic subjects on two different days. The whole sample method was used for analysis, and inflammatory cells were counted on cytospin slides. Reproducibility, expressed by intra-class correlation coefficients, was good for macrophages (+0.80), neutrophils...