FeNO Test Shows Promise in Detecting Polyps in Asthma Patients

Mauro Maniscalco, MD, PhD

While nasal polyposis does not cause asthma, it can cause chronic rhinosinusitis, which in turn can exacerbate asthma. Diagnosis usually involves endoscopy or imaging, but a new study found that the less invasive fractal exhaled nitric oxide (FeNO) test might improve nasal polyposis detection in those with severe asthma.

According to the American Academy of Allergy, Asthma, and Immunology (AAAAI), 26% to 56% of patients with chronic rhinosinusitis with nasal polyposis (CRSwNP) have asthma. The combination can cause breathing and other nasal symptoms to become worse.

Along with asthma exacerbations, symptoms might include nasal drainage and congestion, a decrease in or loss of sense of smell, and facial pain.

It is not known why nasal polyposis develops, but biopsies of polyp tissue have shown elevated eosinophil levels. Certain cells associated with inflammation produce nitric oxide, which makes the FeNO test a reliable indicator of asthma.

The purpose of this study, explained by investigators—led by Mauro Maniscalco, MD, PhD—is to explore the relationship between FeNO levels and nasal polyposis.

Subjects included 93 patients with asthma getting care at 4 specialty clinics in Italy between 2015-2018. All had severe asthma with treatment plans that included daily doses of inhaled corticosteroids (ICS). To construct a baseline, patients completed a questionnaire on medical history and then given atopy assessments, and spirometry. On a second visit, blood eosinophil and FeNo levels were calculated.

Results showed that high eosinophil count (>420 cells/mm³) and higher FeNo levels (39 ppb or greater) were associated with nasal polyposis. In addition, out of the 28 patients that had nasal polyposis, 3 had both low eosinophil counts and FeNO, but 25 had either high eosinophil levels or FeNO. Adding FeNO seemed to improve classifying patients who have nasal polyposis, but have low blood eosinophil levels.

“The results from our study suggest investigating nasal polyposis comorbidity in all severe asthmatic patients with elevated FeNO levels, including the subgroups with normal or low blood eosinophil count,” investigators wrote.

Limitations included the patient population size, 11 subjects being current smokers, and ICS treatment, as both smoking and ICS can impact FeNO levels.

In an interview with MD Magazine® while at the AAAAI 2018 Annual Meeting last year, Marc Massanari, PharmD, explained that FeNO monitoring plays a critical role in promptly and effectively treating patients with asthma.

“There really is no other biomarker test on the market today that allows a clinician at the bedside to know how inflammation is in a patient’s lung,” Massanari said. “So it’s an important test, and I think it has a very large impact on the clinician to then assess the patient and improve their level of asthma control.”

The study, “Association between exhaled nitric oxide and nasal polyposis in severe asthma,” was published online in Respiratory Medicine.