Spirometry‐adjusted fraction of exhaled nitric oxide increases accuracy for assessment of asthma control in children

Abstract

Spirometry and exhaled nitric oxide are two important complimentary tools to identify and assess asthma control in children. We aimed to determine the ability of a new suggested spirometry-adjusted fraction of exhaled nitric oxide (NO) index in doing that. A random sample of 1602 schoolchildren were screened by a health questionnaire, skin prick tests, spirometry with bronchodilation and exhaled NO. A total of 662 children were included with median (IQR) exhaled NO 11(14) ppb. Receiver operating characteristic (ROC) curves using exhaled NO equations from Malmberg, Kovesi and Buchvald, and spirometry-adjusted fraction of exhaled NO values were applied to identify asthmatic children and uncontrolled asthma. Receiver operating characteristic (ROC) curves failed to identify asthmatic children (all AUC < 0.700). Spirometry-adjusted fraction of exhaled NO/FEV (AUC = 0.712; P = .010) and NO/FEF (AUC = 0.735 P = .004) had a fair and increased ability to identify uncontrolled disease compared with exhaled NO (AUC = 0.707; P = .011) or the Malmberg equation (AUC = 0.701; P = .014). Sensitivity and specificity identifying non-controlled asthma were 59% and 81%, respectively, for the cut-off value of 9.7 ppb/L for exhaled NO/FEV , and 40% and 100% for 15.7 ppb/L/s for exhaled NO/FEF . Exhaled NO did not allow to identify childhood asthma. Spirometry-adjusted fraction of exhaled NO performed better-assessing asthma control in children. Thus, although more validation studies are needed, we suggest its use in epidemiological studies to assess asthma control.

Setting definitions of childhood asthma in epidemiologic studies

“…In our decision tree, the probability of having airway reversibility was higher in those who had higher values for pattern 4, “non‐specific respiratory symptoms.” Exhaled NO showed a very low diagnostic accuracy. However, a spirometry‐adjusted fraction of the eNO index has performed better for assessing children's asthma . Because objective evaluations are non‐invasive and simple to perform in epidemiological studies, they are probably useful to include in a composed score.…”

“…However, a spirometry-adjusted fraction of the eNO index has performed better for assessing children's asthma. 20 Because objective evaluations are non-invasive and simple to perform in epidemiological studies, they are probably useful to include in a composed score. However, they are also affected by asthma treatment and control.…”

Asthma control in children: Body plethysmography in addition to spirometry

“…In the last years, several studies examined if the latter agree with asthma control in children. While some authors found a correlation between the parameters, most of the authors did not …”

“…One of the frequently used questionnaires is the asthma control test (ACT), for which a version for children younger than 12 years is also available (c‐ACT) . Objective methods to assess asthma control include measures of spirometry and fractional concentration of nitric oxide in exhaled air (FeNO) . In the last years, several studies examined if the latter agree with asthma control in children.…”

“…4,5 Objective methods to assess asthma control include measures of spirometry and fractional concentration of nitric oxide in exhaled air (FeNO). [6][7][8][9][10][11][12][13] In the last years, several studies examined if the latter agree with asthma control in children. While some authors found a correlation between the parameters, [6][7][8] most of the authors did not.…”