Is wet or productive cough a valid symptom in older children? Correlation of parent and physician perceived cough quality with the bronchoscopic findings

Abstract

Rationale: Cough is the most common symptom presenting to doctors. The quality of cough (productive or wet vs dry), a frequently used concept in clinical and research, has been shown to be valid in young children (viz, secretions present in the lower airways of children with wet cough). However, there is no such data on the validity of cough quality in older children. Thus, in this study involving children aged >5-years, we compared the (1) cough (wet/dry) and huff quality to bronchoscopic findings of secretions respectively and, (2) parent's vs clinician's evaluation of the cough quality (wet/dry). Methods: Children (without a known underlying respiratory disease) were recruited 1-3 hours before elective bronchoscopy. Their cough and huff (voluntarily i.e. nonspontaneous) was digitally recorded. Parent(s) were asked about their child's cough quality (productive/wet vs. dry) over the last 24-hours. A 'blinded' clinician scored the secretions seen at bronchoscopy on pre-determined criteria and graded (1 to 6), using a validated tool (bronchoscopy secretions, BS tool). A second 'blinded' physician independently scored the cough/huff sounds. Weighted kappa (K) statistics was used for agreement. A receiver operating characteristic (ROC) curve was used to determine if cough quality related to amount of airway secretions present at bronchoscopy. Results: Median age of the 34 children (14 boys) enrolled was 8.4-years (range 6.67-11.54). Chronic cough was the most common indication for bronchoscopy (n=29, 85.2%). BS grades were done in real time in all but one child. Parents' assessment of cough quality (wet or productive vs. dry) only moderately agreed with clinicians' single cross sectional assessment (K=0.47, 95%CI 0.41-0.53). When compared to bronchoscopy (BS grade ≥4), parent(s)' cough assessment had the highest area under the ROC curve (aROC=0.71 95%CI 0.64-0.99). That for clinicians was 0.38, 95%CI 0.07-0.62. The clinician's huff assessment was marginally better in diagnosing BS ≥grade 4 aROC= 0.57, 95%CI 0.37- 0.90, although still poorer than parents'. Intra-rater (K=0.84, 95%CI 0.69-0.99) and inter-rater clinician agreement for wet/dry cough (K=0.61, 95%CI 0.56-0.66) was good. Conclusions: In children aged >5 years, parental report of wet cough has good clinical validity in predicting significant lower airway secretions as determined by bronchoscopy. Unlike in previous studies on younger children, the clinician's single cross sectional assessment of cough and huff quality in older children may not accurately predict the presence of lower airway secretions although huff may be marginally superior to cough in a clinic setting.L6229696202018-07-16 <br />