Background: The coding region variant Arg16Gly at the beta2-adrenoceptor gene (ADRB2) is functionally relevant, and is common in Japanese. Longer term clinical responses to short-acting and long-acting beta2 agonists have been influenced by the Arg16Gly polymorphism. The purpose of the present study is to assess the clinical effects of real life usage of beta2-agonist (long-acting beta2-agonist, regular use of short-acting beta2 agonist, or oral beta2-agonist), as an add-on medication to inhaled steroids, in Arg/Arg and Gly/Gly patients with asthma.
Methods: In a retrospective analysis of outpatient records, 27 patients with Arg/Arg and 35 patients with Gly/Gly had regular usage of beta2-agonist, whereas 37 patients with Arg/Arg and 29 patients with Gly/Gly had as-needed usage of beta2-agonist. During the follow-up periods at Hokkaido University Hospital, long term bronchodilator responses were assessed using 3 indexes: 1) improvement in FEV1 (DeltaFEV1 [ml]), 2) DeltaFEV1/FEV1 at an initial visit, 3) DeltaFEV1/predicted FEV1.
Results: In patients with Gly/Gly genotype, compared with as-needed usage of beta2-agonist, the regular usage of beta2-agonist was associated with greater improvement in FEV1 in every index (p=0.027-0.041). In contrast, in patients with Arg/Arg genotype, the regular usage of beta2-agonist showed no greater improvement in FEV1 compared with as-needed beta2-agonist usage.
Conclusion: Gly/Gly and Arg/Arg genotype responses to regular usage of beta2-agonists may differ in patients with asthma.