Ginkgo Biloba for Acute Ischemic Stroke
Section Editor: Graeme J. Hankey MD, FRCP
Ginkgo biloba extract, a Chinese traditional medicine, is used widely in the treatment of acute ischemic stroke in China and is also used occasionally in Europe, but its efficacy is uncertain.
The primary objective was to determine whether Ginkgo biloba extract improves functional outcome without causing undue harm in patients with acute ischemic stroke. Secondary objectives were to assess the effect of Ginkgo biloba extract on neurological impairment and quality of life.
We searched the Cochrane Stroke Group Trials Register (last searched October 2004), the Trials Register of the Cochrane Complementary Medicine Field (last searched October 2004) and the Chinese Stroke Trials Register (last searched June 2004). In addition, we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 3, 2004), MEDLINE (1966 to August 2004), EMBASE (1980 to June 2004), AMED (1985 to May 2002) and the China Biological Medicine Database (CBM-disc, 1979 to August 2004). We searched relevant clinical trials and research registers and contacted pharmaceutical companies and researchers in an effort to identify further published and unpublished studies.
Selection criteria comprised randomized controlled trials or quasi-randomized controlled clinical trials comparing Ginkgo biloba extract with placebo or open control (no placebo) in patients with acute ischemic stroke.
Data Collection and Analysis
Two reviewers independently selected trials for inclusion, assessed trial quality, and extracted the data.
Fourteen trials were identified, of which 10 trials (792 patients) were included. The other 4 trials are awaiting assessment. In the 10 included trials, follow-up was performed at 14 to 35 days after stroke. In all studies, neurological outcome was assessed, but none of them reported on disability (activities of daily living function) or quality of life. Only 3 trials reported adverse events. In nine trials, significant improvement in neurological deficit at the end of the treatment was used as the outcome measure. But all of them were assessed to be of inferior quality, particularly because there was uncertainty whether or not the trials were truly randomized with adequate concealment of allocation. When analyzing these trials together, Ginkgo biloba extract was associated with a significant increase in the number of improved patients (Peto odds ratio [OR], 2.66; 95% CI, 1.79 to 3.94; Figure 1). One placebo-controlled trial, assessed to be of good quality, reported neurological outcome as a continuous variable. It failed to show an improvement of neurological deficit at the end of treatment (weighted mean difference [fixed], 0.81; 95% CI, −8.9 to 10.52; Figure 2). No deaths or major adverse events were reported during the follow-up period.
Implications for Practice
There is no scientific support from high-quality studies for the routine use of Ginkgo biloba extract in the treatment of patients with acute ischemic stroke.
Implications for Research
Our meta-analysis suggests that Ginkgo biloba extract intravenous injections and tablets improve neurological impairment after acute ischemic stroke. However, a caveat is that with 1 exception, the trials included were assessed to be of inferior methodological quality. High-quality, large-scale randomized trials are needed to confirm or refute the results. Future trials should overcome the methodological limitations of the trials presented in this review. In particular, they should assure true randomization, adequate concealment of allocation, blinding of outcome assessors, use functional outcome as the primary outcome measured at long-term follow-up, and they should be large enough to provide adequate statistical power.
- Received September 15, 2005.
- Accepted October 11, 2005.