2.5. Data analysis

A meta‐analysis was conducted using Review Manager 5.3. The risk ratio (RR) with a 95% CI was used for the improvement of symptoms, while the weighted mean difference (WMD) with a 95% CI was adopted for the changes of blood viscosity and cerebral blood flow rate revealed by transcranial Doppler (TCD). Heterogeneity was assessed by the visual inspection of forest plots, p‐values, and I ² statistics. p> .10 and I ² < 50% suggested a lack of significant heterogeneity; in such cases, a fixed‐effects model was used for the meta‐analysis. For cases with p < .10 and I ²> 50%, we explored sources of heterogeneity. When no clinical heterogeneity was indicated, a random‐effects model was used to perform the meta‐analysis. A value of p < .05 was considered to be statistically significant.

A funnel plot was used to assess publication bias. An Egger test and Begg test were also used to analyze the potential publication bias. A value of p> .05 meant that the risk of publication bias was small, while p < .05 meant that publication bias might exist.