Introduction: One possible reason for the persisting controversy about bronchodilator responsiveness (BDR) in asthma is the lack of sufficiently sensitive definition based on age

Objectives: To assess whether the BDR is dependent or not to the age in asthmatic patients.

Methods: We have conducted a retrospective study, involving asthmatic patients in the Physiology and functional exploration department of Habib Bourguiba hospital of Sfax. Basing on their age , the patients were divided in 4 groups : G1 (infants aged < 10 years old), G2(adolescents aged between 10 and 19 years old) , G3 (adults aged between  19 and 64 years old) and G4 (age > 65 years old).Spirometry was performed before and after BD. BDR was assessed according these three methods: the M200 (=increase of FEV1 by 200 ml ), the M12  (= increase of FEV1 by 12 % of the initial value ) and the M10 (= increase of FEV1 by 10 % of theorical value ).For statistical purpose , we have used the SPSS 20.A p < 0.05 was significant.

Results:   435 patients (G1=100, G2=88 , G3=181  and G4 =34) were included in this study. The percentage of BDR by M10 was 35.8 % higher than those of M12 (26.1%) and M22 (30.0%) (p<0.05). There was no significant correlation between age and the FEV1 after BD variation expressed on absolute value and percentages However , the G3 of adults showed significant higher percentages of BDR with respectively 44.6% by M200, 31.4 % by M12 and 36.8 % by M10 (P<0.05).While in patients of G4  the percentages were the lowest respectively 5 % by M200, 8.6% by M12 and 11.8 % by M10 (P<0.05)

Conclusion: There is no doubt that the BDR depends on age. An age dependent cut-off points should be proposed in the definition of BDR in asthma.