Cough features, concomitant symptoms, history useful to determine causes of chronic cough

Cough timing, concomitant symptoms associated with gastroesophageal reflux or rhinitis/sinusitis and medical history are useful clinical characteristics that can aid in the prediction of causes of chronic cough, researchers reported.

“To our knowledge, this is the first study with [a] large sample size to investigate the diagnostic value of cough features in patients with chronic cough,” Kefang Lai, MD, PhD, professor in the State Key Laboratory of Respiratory Disease in the National Clinical Research Center for Respiratory Disease at Guangzhou Institute of Respiratory Health, Guangzhou, China, and colleagues wrote in The Journal of Allergy and Clinical Immunology: In Practice.

The researchers evaluated 1,162 adults with chronic cough as a primary presenting symptom and identified patients with a single underlying cause. Patients completed a questionnaire to record clinical features of cough. The researchers then analyzed the relationships between these clinical features and cause of chronic cough.

In the cohort, 222 patients (mean age, 42 years; 74.3% women) were diagnosed with cough variant asthma, 259 patients (mean age, 42.3 years; 51.4% women) were diagnosed with eosinophilic bronchitis, 145 patients (mean age, 40.8 years; 45.5% women) were diagnosed with gastroesophageal reflux-related cough, 85 patients (mean age, 39.2 years; 44.7% women) were diagnosed with upper airway cough syndrome and 451 patients (mean age, 44.3 years; 53.7% women) were diagnosed with other causes.

Nocturnal cough alone was identified as a predictor of cough variant asthma (OR = 2.037; 95% CI, 1.003-4.139; specificity, 97.6%; sensitivity, 8.1%).

Heartburn (OR = 2.671; 95% CI, 1.544-4.62), belching (OR = 2.536; 95% CI, 1.62-3.971) and acid regurgitation (OR = 2.043; 95% CI, 1.299-3.212) indicated gastroesophageal reflux-related cough (specificity, 85.5% to 94.9%; sensitivity, 22.8% to 40.7%). Further, cough after meals was associated with a 91.2% specificity and 24.8% sensitivity for gastroesophageal reflux-related cough.

Postnasal drip (OR = 2.317; 95% CI, 1.425-3.767) and history of sinusitis (OR = 4.137; 95% CI, 2.483-6.892) indicated upper airway cough syndrome (specificity, 80.8% and 90.2%, respectively). Researchers reported that rhinitis/sinusitis-related symptoms showed moderate sensitivity (72.9%) and mild specificity (46.1%) for upper airway cough syndrome.

“Nocturnal cough indicates cough variant asthma. If a patient has reflux symptoms or cough after meals, gastroesophageal reflux-related cough should be considered. If a patient presents with postnasal dripping and/or rhinitis/sinusitis-related symptoms, the diagnosis of upper airway cough syndrome should be high on the differentials,” the researchers concluded. “These clinical features can be useful in indicating common causes of chronic cough and guiding empiric therapy.”