Diagnostic accuracy of exhaled nitric oxide in exercise-induced bronchospasm: Systematic review

The gold-standard method for the diagnosis of exercise-induced bronchospasm (EIB) is an exercise test combined with spirometry. However, this test is expensive, time consuming and requires specialized equipment and trained personnel. Exhaled nitric oxide (eNO) is a fast, easy, noninvasive method for the diagnosis of EIB. The aim of the present study was to assess the accuracy of the measurement of eNO for the diagnosis of EIB through a systematic review of the literature.

A search was carried out in the PubMed, Lilacs, SciELO and SCOPUS databases by two independent researchers.

Fifty-six papers were found. Following the application of the eligibility criteria to the title, abstract and text, six papers remained for analysis. There was a significant heterogeneity in sex (X(2)=56.44, p=0.000) and clinical spectrum (X(2)=504.00, p=0.000) between studies. In children between 3.8 and 7.8 years old a cutoff point >28ppb EIB can be ruled in and in children between 5 and 16 years old at a cutoff point <20EIB can be ruled out. For adults a cutoff point <7EIB can be ruled out and it can be ruled in with a cutoff point >12. Four papers reported negative predictive values above 88%.

The measurement of eNO seems to be effective for ruling in and ruling out EIB in some specific groups. Therefore, the measurement of eNO levels could be an important tool to safely avoid the need for an exercise test when the result is negative, reducing the individual and economic impact of this disease.