Literature search strategy
Meta-analysis was performed according to the Preferred Reporting Items
for Systematic Reviews and Meta-Analyses (PRISMA) guidelines[21]. We searched PubMed, EMbase, Web of Science,
The Cochrane Library, CBM, CNKI, WanFang Date and VIP from establishment
to August 2020. The search strategy included a combination of subjects
and words as follows: (‘asthma’) AND (‘albuterol’ OR ‘salbutamol’) AND
(‘Receptors, Adrenergic, beta-2’ OR ‘ADRB2 ’ OR ‘adrenergic
receptor’ OR ‘Beta 2 Adrenergic Receptors’ OR ‘Receptors, beta-2
Adrenergic’ OR ‘Receptors, beta 2 Adrenergic’ ) AND (‘polymorphism’ OR
‘SNP’ OR ‘variation’ OR ‘variant’ OR ‘mutation’). To find previously
unconfirmed studies, we also searched references cited in the relevant
articles manually. The search results were limited to human.