Background: Several biologics are now available as add-on treatment for severe asthma but, currently there are no universally accepted criteria to measure the response to these therapies. This survey aims to establish consensus criteria to use in practice for the initial evaluation of response to biologics after four months of treatment. Method: Using Delphi methodology, a questionnaire including ten items was developed and validated by a 13-member panel of international experts in asthma. The electronic survey circulated within the INterasma Scientific Network platform, Global Asthma Association membership, contact list of the co-authors, national associations for specialists, and social media. For each item, five answers were proposed graduated from “no importance” to “very high importance” and by a score (A=2 points; B=4 points; C=6 points; D=8 points; E=10 points). The final criteria were selected if the median score for the item was ≥7 and >60% of responses accorded “high importance” and “very high importance”. All selected criteria were validated by the thirteen experts. Results: Four criteria were identified to evaluate the efficacy of biologics in asthma: to reduce daily systemic corticosteroids dose by ≥50% (ideally complete withdrawal); to decrease the number of asthma exacerbations requiring systemic corticosteroids by ≥50%, (ideally no asthma exacerbation); to have no/minimal side-effects and to obtain asthma control according validated questionnaires. The consensual decision was that ≥3 criteria are needed to conclude a good response to biologics. Conclusions: Specific criteria were defined by an international panel of experts and could be used as tool in clinical practice.

Asthma assessment by spirometry is challenging in children as forced expiratory volume in one second (FEV1) is frequently normal at baseline. Bronchodilator (BD) reversibility testing may reinforce asthma diagnosis but FEV1 sensitivity in children is controversial. Ventilation inhomogeneity, an early sign of airway obstruction, is described by the upward concavity of the descending limb of the forced expiratory flow-volume loop (FVL)s, not detected by FEV1. The aim was to test the diagnosis ability of FVL shape indexes as β-angle and forced expiratory flow at 50% of the forced vital capacity (FEF50)/peak expiratory flow (PEF) ratio, to identify asthmatics from healthy children in comparison to “usual” spirometric parameters. Seventy-two asthmatic children and twenty-nine controls aged 8 to 11 years were prospectively included. Children performed forced spirometry at baseline and after BD inhalation. Parameters were expressed at baseline as z-scores and BD reversibility as percentage of change reported to baseline value (Δ%). Receiver operating characteristic curves were generated and sensitivity and specificity at respective thresholds reported. Asthmatics presented significantly smaller zβ-angle, zFEF50/PEF and zFEV1 (p≤0.04) and higher BD reversibility, significant for Δ%FEF50/PEF (p=0.02) with no difference for Δ%FEV1. zβ-angle and zFEF50/PEF exhibited better sensitivity (0.58, respectively 0.60) than zFEV1 (0.50), and similar specificity (0.72). Δ%β-angle showed higher sensitivity compared to Δ%FEV1 (0.72 vs 0.42), but low specificity (0.52 vs 0.86). Quantitative and qualitative assessment of FVL by adding shape indexes to spirometry interpretation may improve the ability to detect an airway obstruction, FEV1 reflecting more proximal while shape indexes peripheral bronchial obstruction.