TY - JOUR T1 - Variability and reproducibility in the measurement of tracheobronchial clearance in healthy subjects and patients with different obstructive lung diseases JF - European Respiratory Journal JO - Eur Respir J SP - 613 LP - 620 DO - 10.1183/09031936.93.01070613 VL - 1 IS - 7 AU - M Del Donno AU - D Pavia AU - JE Agnew AU - MT Lopez-Vidriero AU - SW Clarke Y1 - 1988/07/01 UR - http://erj.ersjournals.com/content/1/7/613.abstract N2 - The purpose of this study was to establish the inter- and intra-subject/patient variability of tracheobronchial clearance, measured for 6 h, using a radioaerosol technique. Inter-subject variability was evaluated in five groups: 33 healthy non-smokers (NS); 19 asymptomatic smokers (S); 40 asthmatics (A); 27 chronic bronchitics (CB) and 12 bronchiectatics (B). Intra-subject variability was evaluated in 16 A and 27 CB who were studied twice. The inter-subject/patient coefficient of variation (CoV) of tracheobronchial clearance was 13% for NS and 28-39% for the remaining four groups. The intra-patient CoV was about half of the inter-patient CoV. Inter-subject CoV (for A and CB) appeared to be independent of initial tracheobronchial deposition of radioaerosol and frequency of cough. We were also able to estimate the approximate number of patients required for a crossover study in order to avoid statistical, type II errors when investigating the effect of a drug or of a therapeutic intervention on tracheobronchial clearance. ER -