Retrieved studies
Based on our search strategy, 387 eligible studies were screened. The titles and abstracts of these studies were filtrated according to inclusion criteria. Finally, seventeen full text articles were eligible for this meta-analysis[7–23] (Fig. 1).
Study Characteristics
Three studies were included on the relationship between serum IL-10 level and ischemic stroke, including 274 patients. A total of fourteen studies which involved 3480 patients with IS were included to explore the relationship between IL-10-1082G/A polymorphism and the risk of IS. There are seven studies involving 1604 patients on the relationship between IL-10-819C/T polymorphism and the risk of IS. In addition, four studies were included to explore the association of IL-10-592C/A polymorphism with the risk of IS, involving 1040 patients.
Publication Bias
A comprehensive design was used in our study to minimize the publication bias. We have two researchers (Yeqin Sha and Xiaodong Rui) performed an intact search strategy and selected studies strictly according to the eligibility criteria and exclusion criteria. Finally, we used heterogeneity test to assess possible publication bias. In this system evaluation no evidence of publication bias was found.
Quantitative Synthesis
The results of this meta-analysis and heterogeneity test were shown in Table 2.We estimated the relationship between serum level of IL-10 or gene polymorphism and the risk of ischemic stroke with the dominant model and the recessive model.
Table 2
ssociation Between IL-10 Gene Polymorphisms and Ischemic Stroke
| | Association | | Heterogeneity |
Genetic model | Subgroup | OR (95% CI) | P | Effect model | I2 (%) | Phet |
IL-10-1082G/A | | | | | | |
A vs. G | Overall | 1.20(0.96–1.49) | 0.11 | R | 78 | 0.000 |
| Chinese | 1.30 (0.99–1.71) | 0.06 | R | 63 | 0.01 |
| Other | 1.11 (0.77–1.59) | 0.58 | R | 86 | 0.000 |
AA vs. AG + GG | Overall | 1.32 (1.02–1.70) | 0.04 | R | 63 | 0.001 |
| Chinese | 1.58 (1.15–2.17) | 0.005 | R | 49 | 0.07 |
| Other | 1.08 (0.72–1.60) | 0.72 | R | 68 | 0.005 |
AA + AG vs. GG | Overall | 1.23 (0.89–1.70) | 0.34 | R | 71 | 0.000 |
| Chinese | 1.46 (1.17–1.83) | 0.001 | R | 0 | 0.64 |
| Other | 1.10 (0.65–1.89) | 0.72 | R | 83 | 0.000 |
IL-10-819C/T | | | | | | |
T vs. C | Overall | 0.99 (0.89–1.11) | 0.92 | F | 0 | 0.47 |
TT vs. TC + CC | Overall | 0.95 (0.82–1.10) | 0.51 | F | 0 | 0.57 |
TT + TC vs. CC | Overall | 1.09 (0.88–1.35) | 0.45 | F | 47 | 0.08 |
IL-10- 592C/A | | | | | | |
A vs. C | Overall | 1.06 (0.93–1.21) | 0.37 | F | 39 | 0.18 |
AA vs. AC + CC | Overall | 1.15 (0.83–1.61) | 0.40 | R | 54 | 0.09 |
AA + AC vs. CC | Overall | 1.10 (0.84–1.44) | 0.50 | F | 0 | 0.78 |
Note:OR, odds ratio; CI, confidence interval; F, fixed-effect model; R, random-effect model. |
Combined analysis indicated that patients with ischemic stroke had significantly lower serum level of IL-10 (Mean difference [MD]: -4.00; 95% confidence interval [CI]: -4.73 to -3.27, Fig. 2.). Funnel plot was implemented in this study and no substantial asymmetry was identified (Fig. 3).
The association between IL-10-1082G/A gene polymorphism and the risk of IS was then explored and significant heterogeneity was found among different ethnicities, therefore sub-group analysis was used. We conducted two subgroups, namely Chinese population and other ethnic groups. It demonstrated that significant association was observed between IL-10-1082G/A polymorphism and the risk of IS among Chinese population (for AA vs. AG + GG: OR = 1.58, 95%CI:1.15–2.17, P = 0.005, Fig. 4) but for other ethnic groups (for AA vs. GA + GG: OR = 1.08, 95% CI: 0.72–1.60, P = 0.72, Fig. 4). Therefore, individuals with AA-genotype might have an increased risk of IS among Chinese Han population.
However, no association was found between polymorphism of IL-10-819C/T and IL-10- 592C/A (TT vs. TC + CC for IL-10-819C/T: OR = 0.95, 95% CI: 0.82–1.10, P = 0.51, Fig. 5; AA vs. AC + CC for IL-10-592C/A: OR = 1.15, 95% CI: 0.83–1.61, P = 0.40, Fig. 6) and the risk of IS among population.