Ginkgo biloba extract for prevention of acute mountain sickness: a systematic review and meta-analysis of randomized controlled trials

Study objective: Trials of ginkgo biloba extract (GBE) for the prevention of acute mountain sickness (AMS) have been published since 1996. Because of their conflicting results, the efficacy of GBE remains unclear. We performed a systematic review and meta-analysis to assess whether GBE prevents acute mountain sickness. Methods: The Cochrane Library, EMBASE, Google Scholar, and PubMed databases were searched for articles published up to May 20, 2017. Only randomized controlled trials were included. AMS defined as acute mountain sickness–cerebral(AMS-C) score≧0.7 or Lake Louise Score (LLS)≧3 with headache. The main outcome measures were the relative risks of AMS in participants receiving GBE for prophylaxis. Meta-analyses were conducted using random-effects models. Sensitivity analyses, subgroup analyses and tests for publication bias were conducted. Results: Six published articles with a total of 451 participants met all eligibility criteria. In the primary meta-analysis of all 7 study groups, GBE showed trend of AMS prophylaxis, but it is not statistically significant (RR =0.68; 95% CI: 0.45 to 1.04; p-value=0.08) (Figure 2). The I2 statistic was 58.7% (p-value=0.02), indicating substantial heterogeneity. The results of subgroup analyses of studies with low risk of bias, low starting altitude (<2500 m), number of treatment days before ascending and dosage of GBE were similar. Conclusions: The currently available data suggest that although GBE may tend toward AMS prophylaxis, there are not enough data to show the statistically significant effect of GBE for preventing AMS. Further large randomized control studies are warranted.