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 doi: https://doi.org/10.1136/bmj.38043.501690.7C (Published 01 April 2004) Cite this as: BMJ 2004;328:797
All rapid responses
Rapid responses are electronic comments to the editor. They enable our users to debate issues raised in articles published on bmj.com. A rapid response is first posted online. If you need the URL (web address) of an individual response, simply click on the response headline and copy the URL from the browser window. A proportion of responses will, after editing, be published online and in the print journal as letters, which are indexed in PubMed. Rapid responses are not indexed in PubMed and they are not journal articles. The BMJ reserves the right to remove responses which are being wilfully misrepresented as published articles or when it is brought to our attention that a response spreads misinformation.
From March 2022, the word limit for rapid responses will be 600 words not including references and author details. We will no longer post responses that exceed this limit.
The word limit for letters selected from posted responses remains 300 words.
EDITOR - We read with interest the paper by Gertsch et al. The
findings may prove useful to those contemplating high altitude treks.
However, there is an important omission in the information provided in the
paper. The number of eligible trekkers who declined to be enrolled in the
trial for a variety of reasons is likely to be high. Data on these
trekkers is not included in the paper but is important, as the trial
participants may not be representative of all non-Nepali trekkers. This
may result in a bias in the trial results such that the effectiveness of
either or both agents is underestimated. This is particularly important
in the case of gingko biloba, which the authors state is not effective
when compared to placebo.
Many non-Nepali trekkers arriving at Pheriche or Dinboche will
already have established views on medication used to combat altitude
sickness. For a large proportion these views may be based on previous
exposure to high altitude and to previous personal benefit of using gingko
or acetazolamide. Some will already be in possession of their drug of
choice and be about to start using it.
Prior formed views on the benefits of a particular drug are highly
likely to cause an individual to want to use that same drug during the
ascent being studied. These individuals are therefore likely to refuse
randomisation between different drugs and placebo and will therefore have
been excluded from this trial. If a significant number of those declining
randomisation had perceived prior benefit from gingko, its effectiveness
will have been underestimated in this trial where the main outcome measure
is a subjective benefit from the randomised agent. Presentation of these
figures is therefore essential for this paper to be adequately analysed by
the reader.
From the information provided it is impossible to comment on the non-
effectiveness of gingko compared with placebo in preventing acute mountain
sickness.
Competing interests:
None declared
Competing interests: No competing interests
Dear Sirs:
I want to bring to your attention the use of homeopathic preparations of
Erythroxylon Coca for the treatment, both prophylactic, and in acute
mountain sickness. I quote from Boericke's Materia Medica: " Coca - the
mountaineer's remedy. Useful in a variety of complaints incidental to
mountain climbing, such as palpitation, dyspneoa, anxiety and insomnia.
Headaches of high altitude, want of breath and shortness of breath in
older athletes". I have used it clinically on patients climbing from 10 to
20,000 feet with great success.
Sincerely,
W. John Diamond, M.D.
Medical Director, InteMedica, LLC
Competing interests:
None declared
Competing interests: No competing interests
I think the authors are being economical with rounding of NNTs in
this paper: The NNT for acetazolamide vs. placebo to prevent an incidence
of acute mountain sickness is 4.60 and should be rounded to 5, not 4. The
NNT for prevention on an incidence of severe headache is 8.51 which should
be rounded up to 9. 95% confidence intervals would normally also be
stated.
Competing interests:
None declared
Competing interests: No competing interests
Exclusion of high risk, low status groups perpetuates discrimination and inequalities
EDITOR - Gertsch et al (2004) report the results of a large, double
blind, randomised controlled trial of ginkgo biloba and acetazolamide for
acute mountain sickness (AMS) in non-Nepali trekkers in the Everest region
of Nepal.(1) However, it is not clear why entry to the study was
restricted to non-Nepali trekkers. Many Nepalis working in the trekking
industry in the Everest region are not the stereotypical Sherpa who has
lived their whole life at altitude. The farmers from the low lands who
undertake a lot of the seasonal portering work in the Everest region are
at similar, if not greater, risk of AMS as western trekkers.(2)
Although including Nepalis at risk of AMS in the study would have
involved some additional logistic arrangements – such as providing study
information in appropriate languages and gaining access to the portering
community – these should not be beyond the abilities of such a large,
international research team. Nor should identifying and excluding those
Nepalis who may not be at risk of AMS due to prolonged acclimatisation.
The exclusion of Nepalis at risk of AMS from the study is
particularly surprising given that one of the authors of the study is
clearly identified as being associated with the Himalayan Rescue
Association – an organisation which disseminates large amounts of
information in the Everest region on the risks of AMS to Nepali porters
working in the trekking industry.(3)
Studies such as this, which exclude high risk, low status groups for
no obvious reason, perpetuate discrimination and inequalities. Evidence
is required on how to prevent AMS in all groups, and not just rich western
tourists.
1. Gertsch JH, Banyat 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,
doi:10.1136/bmj.38043.501690.7C (published 11 March 2004)
2. http://www.portersprogress.org/
3. http://www.himalayanrescue.com/
Competing interests:
None declared
Competing interests: No competing interests