Phenotypes of Cough in Children: A Latent Class Analysis

Distinguishing phenotypes in children presenting with cough can help distinguish varying mechanisms for cough, assist with work-up, and help guide the treatment and management.The study included 531 children from the Swiss Pediatric Airway Cohort between the ages of 5 and 16 years old as this age group could undergo lung function testing and skin prick testing. Inclusion criteria included patients whose parents completed a baseline parental questionnaire reporting any type of cough. Those who had reported a wheeze in the last 12 months were excluded.The study was structured as a prospective clinical study with the goal of conducting a latent class analysis. Swiss Pediatric Airway Cohort includes 8 pediatric respiratory clinics and 2 pediatric practices in Switzerland. The population consisted mainly of French- and German-speaking families of Swiss nationality. The following 9 indicator variables were included in the analysis: frequency of colds, pneumonia, otitis media, regular snoring, rhino-conjunctivitis, dry night cough, type of cough, duration of cough, and number of allergic cough triggers. The cough phenotypes were characterized by how they differed in patient-reported information, pediatric pulmonologist diagnoses, results of measurable traits, and prognosis of respiratory symptoms 1 year later. The phenotypes were then validated against measurable traits, including BMI, fractional exhaled nitric oxide , skin prick test results, and others. They then compared the prognosis between the 4 phenotypes 1 year later. The results were then analyzed via various statistical methods to identify the different cough phenotypes by fitting latent class models to the dataset.Investigators chose to use a statistical model that yielded 4 different cough phenotypes. The 4 phenotypes were (1) nonspecific cough (26%), (2) nonallergic infectious and night cough with snoring and otitis (4%), (3) chronic allergic dry night cough with snoring (9%), and (4) allergic noninfectious cough with rhino-conjunctivitis (61%). Certain characteristics were more common in certain phenotypes than others. For example, children with phenotype 2 were more often male and younger. Children with phenotype 4 more often had a history of eczema, hay fever, and asthma.The study applied latent class analysis to identify different phenotypes of cough in children. Four phenotypes were identified, with allergic noninfectious cough with rhino-conjunctivitis being the most common. The 4 categories varied with regards to patient reported information, pediatric pulmonology diagnoses, measurable traits, and their prognosis 1 year later.Other studies have been done that investigated cough etiologies in children, but this study was the first of its kind to use latent class analysis and focused distinctly on cough-related concerns. Interestingly, most children had an allergic phenotype. The homogenous nature of the patient population limits the generalizability of these findings. This study suggests that there should be a lower threshold to consider allergy and asthma work-up when evaluating cough in children.