Introduction: The ATS/ERS 2021 (AE21) proposed a new definition of the bronchodilator (BD) responsiveness (BDR) basing on the increase of the forced expiratory volume in 1 second (FEV 1) or the forced vital capacity over 10 % of the predicted value. Objectives: To assess whether the AE21 BD definition is valid or not in asthmatic adults.

Methods: We have conducted a retrospective study, involving asthmatic adults   in the Physiology and functional exploration department of Habib Bourguiba hospital of Sfax. Spirometry was performed before and after BD. Significant BDR was established according three definitions the AE21, the ATS/ERS 2005 (AE05) (increase of FEV1 or FVC by 200 ml and 12 % of the initial value) and the GINA 2022 (G21) (increase of FEV1 by 12 % and 200 ml). For statistical purpose, we have used the SPSS 20.A p < 0.05 was significant.

Results: Among 100 included adults, 69.3% were females The mean age was of 52.1±13.61 years old. The percentage of BDR by AE21 was 42.6 % significantly higher than those of AE05 (22.8%) and G21 (18.8%) (p<0.05). These percentages were higher among mans with respectively 50% by AE21, 30 % by AE05 and 26.7 % by G21 (P<0.05). In patients with BMI > 25 kg/m² the percentages were respectively 45.3% by AE21, 22.7 % by AE05 and 18.7 % by G21 higher than those with BMI<25 kg/m² (respectively 36% by AE21, 24 % by AE05 and 20 % by G21)

Conclusion: The BR assessment depends on the scholarly society. The ATS/ERS 2021 definition provides a significantly higher BR rate than ATS/ERS 2005 and GINA 21 ones and seems more suitable for mans that women. Prospective randomized studies would help standardize the interpretation of BR in asthmatic adults.