Nocturnal cough in children with stable cystic fibrosis.

Introduction: To date no studies have been published on nocturnal cough frequency in children with stable CF. Aim of the study was to assess nocturnal cough frequency in children with CF. In addition nocturnal cough frequency was correlated with parameters of disease severity.

Methods: During two nights cough was recorded with a digital audio recorder in 25 patients (mean age 13 years; range 6-19) with clinically stable CF. In addition oxygen saturation was measured. The day following the recording spirometry was carried out. CT scores were obtained from the most recent routine CT scan. Cough was expressed in cough seconds (csec) and in cough seconds per hour (csec/hr).

Results: Data shown are median values and interquartile range (IQR). First night: 8 csec (IQR 3-52); 0.9 csec/hr (IQR 0.3-6.1) Second night: 6 csec (IQR 2-32); 0.6 csec/hr (IQR 0.1-3.4). Csec in the 1st night did not correlate significantly with csec in the 2nd night. Only for the 2nd night a strong correlation was found between csec/hr and the FEV1%pred (r(s) = -0.75, P < 0.001) and FEF(75) %pred (r(s) = -0.71, P < 0.001). Bronchiectasis score correlated borderline with the mean csec/hr of both nights (r(s) = 0.39, P = 0.08). During both nights cough was significantly higher in the first hour of sleep (P < or = 0.04).

Conclusion: Frequency of nocturnal coughing in children with CF was higher than that described for normal children. Nocturnal cough tended to be more severe in children with more advanced CF lung disease. Nocturnal cough was more severe in the first hour of sleep and varied from night-to-night.