PAI-1 Gene Polymorphism Was Associated with an Increased Risk of Allergic Diseases: Evidence from a Meta-Analysis of 14 Case-Control Studies

Introduction: In recent years, many studies have focused on the association between plasminogen activator inhibitor (PAI)-1 gene 4G/5G polymorphism and risk of allergic diseases, but the results have been inconclusive. Objective: We conducted this meta-analysis to study the exact relationship between PAI-1 polymorphism and susceptibility to allergic diseases. Methods: All eligible studies were determined by an electronic literature search. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association under all of the models. Results: A total of 14 studies involving 2,327 cases and 2,838 controls were included in this meta-analysis. Overall, we found a significant association between PAI-1 polymorphism and risk of allergic diseases (4G/4G + 4G/5G vs. 5G/5G: OR 1.76, 95% CI 1.39-2.22, p < 0.00001). In a subgroup analysis by ethnicity, we found a markedly increased risk in Asians (OR 1.62, 95% CI 1.26-2.09, p = 0.0002) and Caucasians (OR 1.78, 95% CI 1.26-2.52, p = 0.001). In addition, significant associations between PAI-1 polymorphism and risk of allergic diseases were observed in both adults (OR 1.71, 95% CI 1.23-2.38, p = 0.001) and children (OR 1.87, 95% CI 1.42-2.46, p < 0.00001). In a subgroup analysis by different allergic diseases, a significantly increased risk was found for asthma (OR 1.78, 95% CI 1.33-2.39, p = 0.001) but not for rhinitis (OR 1.51, 95% CI 0.79-2.89, p = 0.22). Conclusion: This meta-analysis demonstrated that PAI-1 gene 4G/5G polymorphism was associated with an increased risk of allergic diseases.