The following is a summary of “Diagnostic impact of fractional exhaled nitric oxide for asthmatic cough in nontuberculous mycobacterial pulmonary disease,” published in the April 2024 issue of Pulmonology by Miki et al.

Measurement of fractional exhaled nitric oxide (FeNO) holds promise as a diagnostic tool for asthma, yet its application in the context of nontuberculous mycobacterial pulmonary disease (NTM-PD) complicated by asthma remains unexplored. This study aimed to investigate the relationship between FeNO levels and respiratory symptoms in NTM-PD patients with asthma comorbidity. In this retrospective cohort study comprising 140 NTM-PD patients  with FeNO measurements, individuals with asthma comorbidity were identified as the NTM+BA group. 

Diagnostic criteria included patients with NTM displaying asthma symptoms or symptomatic improvement following inhaled corticosteroid (ICS) therapy with or without a long-acting beta 2-agonist (LABA). A diagnostic cutoff point for distinguishing between NTM+BA and NTM-only groups was determined, alongside an assessment of HRCT findings and their association with FeNO levels. The NTM+BA group, comprising 31 patients, exhibited significantly higher FeNO levels (median 23 [IQR 15.0-43.0] ppb) and a higher prevalence of allergic disease compared to the NTM-only group (median 17 [IQR 11.8-23.0] ppb; p=0.015; 51.6% vs. 22.4%, respectively; p=0.0085). 

Notably, diagnostic asthma management guided by FeNO levels led to symptom improvement in 91.0% of patients with NTM+BA, with stable acid-fast bacilli (AFB) culture findings post-treatment. A FeNO cutoff point of 21.5 ppb effectively distinguished between NTM+BA and NTM-only groups (sensitivity 75%, specificity 71.93%, p<0.0001; AUC: 0.7989), independent of CT image severity. These findings underscore the potential of FeNO measurement in identifying asthma comorbidity in NTM-PD patients, facilitating tailored diagnostic and therapeutic strategies.

Source: bmcpulmmed.biomedcentral.com/articles/10.1186/s12890-024-03028-3