Comparison of Nocturnal Cough Analysis in Healthy Subjects and in Patients with Cystic Fibrosis and Primary Ciliary Dyskinesia: A Prospective Observational Study

Abstract

Background: Cough is a key symptom in patients with cystic fibrosis (CF) and primary ciliary dyskinesia (PCD). Objective: The study objectives were to test whether cough is related to parameters reflecting their disease severity and whether CF and PCD differ in cough frequency. Methods: In this prospective observational study, we used a microphone-based monitoring system (LEOSound® Monitor) to count the coughs in healthy subjects (HS) and in stable patients with CF and PCD (25 subjects per group) on 2 consecutive nights. Results: The median number of coughs/h in the HS, CF, and PCD groups was 0.0, 1.3, and 0.5 on the first night and 0.0, 2.3, and 0.2 on the second night, respectively. Patients with CF and PCD coughed more than HS (p < 0.001 and p = 0.009, respectively) and CF patients coughed more than PCD patients (p = 0.023). A multivariable mixed model analysis revealed forced expiratory volume in 1 s as an independent risk factor for increased cough frequency in patients. The reliability for repeated measurements was higher for cough epochs/h than for coughs/h (intraclass correlation coefficient: 0.75 and 0.49, respectively). Conclusions: Patients with CF cough more than patients with PCD. The cough frequency in CF and PCD is associated with parameters reflecting disease severity. Cough frequency is a possible endpoint in clinical trials and cough epochs/h may be more useful than coughs/h.