Meta-regression analysis and publication bias:
Meta-regression analysis was used to explore possible sources of
heterogeneity and to find characteristics of participants or trials with
effective treatment effects. The result of univariate meta-regression
analysis didn’t show a significant linear association between soy
isoflavones dose and effect size of soy isoflavones effect on CRP levels
(Coefficient= -0.0004, 95% CI: -0.03, 0.03; P=0.977) (Table 5& Figure 5 ). Also, after adjustment for design, intervention
duration, baseline CRP, health status, sample size, region, age, BMI,
quality assessment, and publication year of article, dose of soy
isoflavones did not have any linear association with effect size of soy
isoflavones effect on CRP levels (Coefficient= 0.009, 95% CI: -0.11,
0.13; P=0.847). We also didn’t find a significant association between
other studied variables and effect size in univariate meta-regression
analysis (table 5 ). Regarding RCTs which indicated soy
isoflavones effect, there was not any evidence of publication bias
(Egger test p-value=0.954) (Figure 6 ).
Although, univariate meta-regression analysis didn’t show a significant
linear association between soy isoflavones dose of combination of soy
isoflavones plus soy protein dose and studied effect size (Coefficient=
-0.008, 95% CI: -0.02, 0.001; P=0.082) (Table 6 & Figure 7 ).
Also, after adjustment for other variables, there was not observed any
significant association between dose of soy isoflavones and studied
effect size (Coefficient= -0.005, 95% CI: -0.02, 0.01; P=0.447).
Although the funnel plot was not visually symmetric for studies included
in meta-analysis of soy isoflavones plus soy protein (Figure
8 ), the results from the Egger test did not show evidence of
publication bias (Egger test p-value=p=0.781).