Page 70 - ADULT-ONSET ASTHMA PREDICTORS OF CLINICAL COURSE AND SEVERITY

ADULT-ONSET ASTHMA – PREDICTORS OF CLINICAL COURSE AND SEVERITY
ABSTRACT
BACKGROUND: Eosinophilic airway in amma on is associated with increased cor costeroid responsiveness in asthma, but direct airway sampling methods are invasive and/or laborious. Minimally invasive markers for airway eosinophilia could present an alterna ve, but es mates of their accuracy vary.
METHODS: We performed a systema c review and searched MEDLINE, Embase and PubMed for studies evalua ng the diagnos c accuracy of markers against a reference standard of induced sputum, bronchoalveolar lavage and/or endobronchial biopsy in pa ents with (suspected) asthma (incep on-August 2014). Unpublished results were obtained by contac ng authors of studies that did not report on diagnos c accuracy, but had data from which es mates could be calculated. Risk of bias was evaluated using QUADAS-2. Meta-analysis was used to produce summary es mates of accuracy.
RESULTS: We included 32 studies: 24 in adults and eight in children. Of these, 28 (84%) showed risk of bias in at least one domain. In adults, three markers had extensively been inves gated: Frac on of Exhaled Nitric Oxide (FeNO) (17 studies; 3,216 pa ents; summary area under the receiver operator curve (AUC) 0.75 (95%CI 0.72-0.78)); blood eosinophils (14 studies; 2,405 pa ents; 0.78 (0.74-0.82)); total Immunoglobulin E (IgE) (7 studies; 942 pa ents; 0.65 (0.61-0.69)). In children, only FeNO (6 studies; 349 pa ents; summary AUC 0.81 (0.72-0.89)) and blood eosinophils (3 studies; 192 pa ents; 0.78 (0.71-0.85)) had been inves gated in more than one study. Induced sputum was most frequently used as the reference standard. Summary es mates of sensi vity and speci city in detec ng sputum eosinophils ≥3% in adults were: 0.66 (0.57-0.75) and 0.76 (0.64-0.85) for FeNO; 0.71 (0.65-0.76) and 0.77 (0.70-0.83) for blood eosinophils; 0.64 (0.42-0.81) and 0.71 (0.42-0.89) for IgE.
INTERPRETATION: FeNO, blood eosinophils and IgE have moderate diagnos c accuracy. Their use as a single surrogate marker for airway eosinophilia in asthma c pa ents will lead to a substan al number of false posi ves and/or nega ves.
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