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)

doi:10.1136/bmj.38043.501690.7C

BMJ 2004;328:797 (3 April), doi:10.1136/bmj.38043.501690.7C (published 11 March 2004)

Paper

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)

Jeffrey H Gertsch, house officer¹, Buddha Basnyat, medical director², E William Johnson, house officer³, Janet Onopa, assistant professor of medicine⁴, Peter S Holck, associate professor of biostatistics⁴, Prevention of High Altitude Illness Trial Research Group

¹ Department of Internal Medicine, Maricopa Medical Center, 2601 E Roosevelt Avenue number O-D-10, Phoenix, AZ 85008, USA, ² Himalayan Rescue Association, Kathmandu, Nepal, ³ University of Washington School of Medicine, Seattle, WA 98195-6410, USA, ⁴ University of Hawaii, John A Burns School of Medicine, Honolulu, Hawaii, USA

Correspondence to: J H Gertsch jeffgertsch{at}hotmail.com

Objective To evaluate the efficacy of ginkgo biloba, acetazolamide,and their combination as prophylaxis against acute mountainsickness.

Design Prospective, double blind, randomised, placebo controlledtrial.

Setting Approach to Mount Everest base camp in the Nepal Himalayasat 4280 m or 4358 m and study end point at 4928 m during Octoberand November 2002.

Participants 614 healthy western trekkers (487 completed thetrial) assigned to receive ginkgo, acetazolamide, combined acetazolamideand ginkgo, or placebo, initially taking at least three or fourdoses before continued ascent.

Main outcome measures Incidence measured by Lake Louise acutemountain sickness score $>=$ 3 with headache and oneother symptom. Secondary outcome measures included blood oxygencontent, severity of syndrome (Lake Louise scores $>=$ 5), incidence of headache, and severity of headache.

Results Ginkgo was not significantly different from placebofor any outcome; however participants in the acetazolamide groupshowed significant levels of protection. The incidence of acutemountain sickness was 34% for placebo, 12% for acetazolamide(odds ratio 3.76, 95% confidence interval 1.91 to 7.39, numberneeded to treat 4), 35% for ginkgo (0.95, 0.56 to 1.62), and14% for combined ginkgo and acetazolamide (3.04, 1.62 to 5.69).The proportion of patients with increased severity of acutemountain sickness was 18% for placebo, 3% for acetazoalmide(6.46, 2.15 to 19.40, number needed to treat 7), 18% for ginkgo(1, 0.52 to 1.90), and 7% for combined ginkgo and acetazolamide(2.95, 1.30 to 6.70).

Conclusions When compared with placebo, ginkgo is not effectiveat preventing acute mountain sickness. Acetazolamide 250 mgtwice daily afforded robust protection against symptoms of acutemountain sickness.

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Exclusion of high risk, low status groups perpetuates discrimination and inequalities: Jean Adams
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