Statistical analysis
Data analysis was conducted using STATA 15.0 (StataCorp, College
Station, TX, USA) software. Six genetic models were analysed, as for
Arg16Gly polymorphism, namely, the dominant model (GG+AG vs. AA),
recessive model (GG vs. AG+AA), allele model (G vs. A), homozygous model
(GG vs. AA), heterozygous model (AG vs. AA) and additive model (GG+AA
vs. AG). We tested whether genotypic frequencies fall within the
Hardy-Weinberg equilibrium (HWE) by the Chi-square test. The impact ofADRB2 polymorphisms (including Arg16Gly ,Gln27Glu) on the
response to salbutamol in asthmatic patients was measured by odds ratio
(OR) and 95% confidence interval (CI). The chi-square-based Cochran’s
Q-test and Higgins (I2) statistics were used to assess
heterogeneity among studies. The random effects model was adopted in
case of evident heterogeneity (P H<0.10
or I2>50%). If no obvious heterogeneity
existed, the fixed effects model was applied
(P H≥0.10 and I2≤50%). To
address significant heterogeneity, subgroup analysis and Galbraith plot
analysis [24] were carried out. Subgroup analyses
were performed by age (adult vs. children) and ethnicity (Caucasian vs.
Asian). Sensitivity analysis was conducted by removing the study
deviating from HWE. To evaluate the robustness of these results,
sensitivity analysis was also employed by omitting one study at a time.
Publication bias was assessed according to the asymmetry of the funnel
plot. Begg’s and Egger’s tests [25] were also
performed to evaluate publication bias and P <0.05 was
interpreted as statistically significant.