The role of inherited thrombophilia in patients with isolated pulmonary embolism: a systematic review and a meta-analysis of the literature

Introduction Venous thromboembolism (VTE) is a common vascular disease that results in deep venous thrombosis (DVT) and pulmonary embolism (PE). Factor V Leiden mutation (FVL) and G20210A prothrombin mutation (PTM) are associated with an increased risk of VTE. Recent studies have reported a lower prevalence of FVL in patients with isolated PE than in patients with DVT with or without PE, suggesting the possibility that the prevalence of FVL in patients with isolated PE may be not significantly different from that of the general population. To address this issue, we performed a systematic review and a meta-analysis of published studies that assessed the prevalence of FVL and/or PTM in patients with isolated PE and in controls without VTE. Methods MEDLINE and EMBASE databases were searched up to October 2013. Pooled odds Ratios (OR) and 95% confidence intervals (CIs) were calculated using a random-effects model. Statistical heterogeneity was evaluated using the Cochran Q and I2 statistics. Results Eighteen studies totalling more than 11,000 patients were included. FVL was found significantly more often in patients presenting isolated PE than in controls (OR 2.06; 95% CI 1.66, 2.56; p < 0.0001). The prevalence of PTM was also significantly different in patients presenting with isolated PE than in controls (OR 2.64, 95% CI 1.92, 3.63; p < 0.0001). Heterogeneity among studies was low. Conclusion FVL and PTM are both associated with isolated PE. However, the association magnitude between PE and FVL mutation appeared to be lower compared to that observed in the general population of VTE patients.