Abstract
BACKGROUND: Acute respiratory illnesses cause substantial morbidity worldwide. Cough is a common symptom in these childhood respiratory illnesses, but no large cohort data are available on whether various cough characteristics can differentiate between these etiologies.
RESEARCH QUESTION: Can various clinically based cough characteristics (frequency [daytime/nighttime], the sound itself, or type [wet/dry]) be used to differentiate common etiologies (asthma, bronchiolitis, pneumonia, other acute respiratory infections) of acute cough in children?
STUDY DESIGN AND METHOD: Between 2017 and 2019, children aged 2 weeks to <= 16 years, hospitalized with asthma, bronchiolitis, pneumonia, other acute respiratory infections, or control subjects were enrolled. Spontaneous coughs were digitally recorded over 24 hours except for the control subjects, who provided three voluntary coughs. Coughs were extracted and frequency defined (coughs/hour). Cough sounds and type were assessed independently by two observers blinded to the clinical data. Cough scored by a respiratory specialist was compared with discharge diagnosis using agreement (Cohen's kappa coefficient [kappa]), sensitivity, and specificity. Caregiver-reported cough scores were related with objective cough frequency using Spearman coefficient (r(s)).
RESULTS A cohort of 148 children (n = 118 with respiratory illnesses, n = 30 control subjects), median age = 2.0 years (interquartile range, 0.7-3.9), 58% males, and 50% First Nations children were enrolled. In those with respiratory illnesses, caregiver-reported cough scores and wet cough (range, 42%-63%) was similar. Overall agreement in diagnosis between the respiratory specialist and discharge diagnosis was slight (kappa = 0.13; 95% CI, 0.03 to 0.22). Among diagnoses, specificity (8%-74%) and sensitivity (53%-100%) varied. Interrater agreement in cough type (wet/dry) between blinded observers was almost perfect (kappa = 0.89; 95% CI, 0.81 to 0.97). Objective cough frequency was significantly correlated with reported cough scores using visual analog scale (r(s) = 0.43; bias-corrected 95% CI, 0.25 to 0.56) and verbal categorical description daytime score (r(s) = 0.39; bias-corrected 95% CI, 0.22 to 0.54).
INTERPRETATION: Cough characteristics alone are not distinct enough to accurately differentiate between common acute respiratory illnesses in children.