Figure 1.

Results of meta-analysis and meta-regression for the association of the APOE ε4 allele with OSA susceptibility. (A) Forest plot summarizing the results of random-effects meta-analysis. Orange boxes and lines show the point and 95% confidence interval estimates of the odds ratios. Red hollow diamond is the overall summary effect with 95% confidence interval, light brown diamond is summary effect after excluding study number 7 (Gozal et al., 2007), and deep brown diamond is summary effect after excluding both study number 7 and study number 5 (Craig et al., 2006). Nc, number of cases of OSA; No, number of controls. (B) Egger's publication bias plot shown the precision (defined as 1/standard error of log OR) on the abscissa and standardized effect size (relative deviate for log OR) on the ordinate. Statistical significance is shown as P_slope and P_bias as explained in the text. A statistically nonsignificant bias (P_bias≥ 0.05) indicates no significant publication bias. (C) Continuous covariates used in meta-regression: mean age (in years, green bars), proportion of males (pink bars), proportion of subjects with European descent (blue bars) and proportion of subjects possessing the APOE ε4 allele (brown bars). The significance of the association of these covariates with study effect sizes is shown as Metareg P. The study number in panel C corresponds to that in panel A.