BackgroundAsthma control refers to the extent to which the
manifestations of asthma have been reduced or eradicated by treatment.
Interleukin-13 (IL-13) has a central role in Th2 response and serves as
a possible therapeutic target in uncontrolled asthma. Fraction of
exhaled nitric oxide (FeNO) and sputum eosinophils have modest
performance in the evaluation of asthma control.
ObjectiveTo assess the diagnostic performance of sputum IL-13 for the
evaluation of asthma control and furthermore to investigate the
performance of sputum eosinophils and FeNO.
MethodsOne hundred and seventy patients with asthma were studied. All
subjects underwent assessment of asthma control by asthma control test
(ACT), lung function tests, FeNO measurement and sputum induction for
cell count identification and IL-13 measurement in supernatants.
ResultsIL-13 (pg/mL) levels in sputum supernatant differed significantly
among patients with well-controlled asthma and those with not
well-controlled asthma [median IQR 78 (66-102) vs. 213 (180-265), P <
0.001]. Receiver operating characteristic (ROC) analysis showed that,
for the whole study population, the diagnostic performance of IL-13 was
superior to both sputum eosinophils and FeNO levels [area under the
curve (AUC) 0.92, 95% CI 0.87 to 0.95 vs. AUC 0.65, 95% CI 0.58 to
0.72 vs. AUC 0.65, 95% CI 0.55 to 0.72, respectively].
ConclusionThe diagnostic performance of sputum IL-13 was superior to
both sputum eosinophils and FeNO levels for the identification of
well-controlled asthma. Sputum IL-13 levels could serve as a useful
biomarker for asthma control assessment
