PREVALENCE OF ELEVATED EXHALED NITRIC OXIDE IN PATIENTS WITH CHRONIC COUGH IN A COMMUNITY SETTING

Abstract

Introduction Physicians are frequently tasked with treating chronic cough (lasting longer than 8 weeks). Among patients who do not smoke cigarettes, the three primary etiologies of chronic cough are postnasal-drip syndrome, gastroesophageal reflux disease, and atypical asthma, which combined account for 92% of chronic cough. The measurement of exhaled nitric oxide in patients with chronic cough can identify patients who will likely improve with inhaled steroids versus those who will likely not, thereby mitigating the need for a trial of corticosteroids. We evaluated 33 patients with chronic cough from our community looking at trends in their history that could possibly be associated with elevated exhaled nitric oxide and the prevalence of elevated levels among these patients. Methods Thirty-three patients who were non-smokers and complained of cough of 8 weeks duration or longer were administered a survey inquiring about the quality of their cough and previous or current steroid use. A single nitric oxide level was recorded for each patient using a NIOX Vero machine. All procedures were in accordance with the Helsinki Declaration as revised in 2013. Results Five of the thirty-three patients had an elevated exhaled nitric oxide (greater than 35 parts per billion), resulting in a 15% prevalence of elevated exhaled nitric oxide. The mean and median of nitric oxide levels were 22.3 ppb and 19 ppb, respectively. Conclusions Although eighty-five percent of our patients with chronic cough did not have elevated exhaled nitric oxide, this measurement can identify a specific pattern of inflammation and is valuable when considering corticosteroid treatment.