Prevalence and features of IOS-defined small airway disease across asthma severities - 12/02/21
Abstract |
Background |
Impulse oscillometry (IOS) is a noninvasive method based on the forced oscillation technique able to detect small airway dysfunction (SAD) in asthma. We aimed to analyze the prevalence and the functional features of IOS-defined SAD across the different Global Initiative for Asthma (GINA) steps.
Methods |
A cross-sectional, single-center study in which 400 consecutive adult patients with physician-diagnosed, community-managed asthma underwent standard spirometry and IOS, and were stratified by stepwise GINA classification. SAD was defined by IOS as a fall in resistance from 5 to 20 Hz [R5–R20]>0.07kPa × s × L−1.
Results |
The prevalence of IOS-defined SAD ranged between 58.3% (GINA step 2) and 78.6% (GINA step 5), without statistically significant difference within GINA steps (p > 0.05 in all comparisons). Isolated SAD (i.e. without proximal airways involvement) was similarly represented across GINA steps 2–4. Peripheral airways resistance (R5-R20) tended to a progressive increase with the worsening of GINA steps, and was significantly higher in steps 4–5 compared to the other steps (p < 0.05).
The proportion of patients with FEF25–75%-defined SAD (<60%) was lower than the IOS-defined one in GINA steps 2–4 (p < 0.05). Only non-significant or weak inverse correlations between R5-R20 and FEF25–75% were observed within each GINA step, with the exception of GINA step 5, which showed a strong, inverse correlation (r = −0.80, p = 0.0005).
Conclusions |
This study shows that first, IOS-defined SAD is overwhelmingly present across asthma severities; second, airways resistance increases with the worsening of GINA steps; and third, SAD may be overlooked by standard spirometry, especially in milder asthma.
Le texte complet de cet article est disponible en PDF.Highlights |
• | In community-managed asthma, the prevalence of IOS-defined SAD and isolated SAD (i.e. without proximal airways involvement) is significantly represented across GINA steps, suggesting that SAD is overwhelmingly present in asthma. |
• | By means of IOS, peripheral airways resistance (R5-R20) increases with the worsening of GINA steps, and particularly in steps 4–5, suggesting SAD implication in the determination of asthma severity. |
• | Conventional spirometry does not reveal the presence of SAD in GINA steps 2-4, as shown by the nonsignificant or weak inverse correlations between R5-R20 and FEF at 25–75%. |
• | A significantly lower proportion of SAD is detected in GINA steps 2–4 by FEF at 25–75%, compared to IOS. |
• | Overall, this suggests that SAD may be adequately assessed by standard spirometry only in most severe cases, and potentially overlooked in all the others. |
Keywords : Asthma, Community-treated asthma, Small airways, Small airways dysfunction, Oscillometry, IOS
Abbreviations : SAD, IOS, FeNO, BMI, FEV1, FVC, FEF25-75, R5-R20, X5, Ax, FRes, ICS, LABA, LAMA
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Vol 176
Article 106243- janvier 2021 Retour au numéroBienvenue sur EM-consulte, la référence des professionnels de santé.
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