Editor—In their randomised controlled trial of gingko biloba and acetazolamide for preventing acute mountain sickness Gertsch et al do not include data on eligible trekkers who declined enrolment.1 These data are important as the trial participants may not be representative of all non-Nepali trekkers. A bias in participants may underestimate the effectiveness of either agent. This is particularly important for gingko, which is stated to be no more effective than placebo.
Figure 1.
Credit: ERNST HAAS/GETTY
Many trekkers arriving in Nepal will have established views on drug treatments for altitude sickness. Some will already be in possession of their drug of choice. Such people are likely to refuse randomisation to drug or placebo and will therefore have been excluded from the trial. If a significant number of these had perceived prior benefit from gingko, its effectiveness will have been underestimated.
From the information provided it is impossible to comment on the non-effectiveness of gingko in preventing acute mountain sickness.
Competing interests: None declared.
References
- 1.Gertsch JH, Basnyat B, Johnson EW, Onopa J, Holck PS. Randomised, double blind, placebo controlled comparison of ginkgo biloba and acetazolamide for prevention of acute mountain sickness among Himalayan trekkers: the prevention of high altitude illness trial (PHAIT) BMJ 2004;328: 797-801. (3 April.) [DOI] [PMC free article] [PubMed] [Google Scholar]