The Role of Fractional Exhaled Nitric Oxide Measurements in Identifying Subjects with Asthma Symptoms in Western Kenya

Abstract

Background: Fractional exhaled nitric oxide (FeNO) is a novel biomarker that is utilized as a tool to assist with the diagnosis and management of asthma in developed countries. Little data exists from sub-Saharan Africa to understand the role for exhaled nitric oxide in subjects suspected of having asthma. In this study, we aim to elucidate if a relationship exists between elevated FeNO levels and symptoms of asthma.

Methods: Using a cluster randomized stratified sampling strategy, 154 subjects age 12 and above in Uasin Gishu County, Kenya were enrolled. Questionnaires including ISAAC written and video questionnaires and the St George’s Respiratory Questionnaire for COPD were completed. Subjects were tested for FeNO, pre-and post-bronchodilator spirometry, and exhaled carbon monoxide. Odds ratios for the presence of asthma symptoms based on FeNO levels above or below a cutoff point of 71 ppb were generated.

Results: Overall, 5.8% of subjects were identified with asthma symptoms by video questionnaires, and 17.5% by written questionnaires. Median FeNO levels were significantly higher in subjects with wheezing compared to those without. The odds ratio for wheezing in individuals with FeNO levels greater than 71 ppb compared to less than 71 ppb was 7.8 (video questionnaire) and 11.3 (written questionnaire).

Conclusions: A statistically significant relationship exists between elevated levels of FeNO and symptoms of asthma in this western Kenyan population. Further work is needed to explore this link for clinical and research purposes.