INTRODUCTION: Up to half of people who ascend to heights above 2500 m may develop acute mountain sickness, pulmonary oedema, or cerebral oedema, with the risk being greater at higher altitudes, and with faster rates of ascent. METHODS AND OUTCOMES: We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of interventions to prevent, and to treat, acute mountain sickness? We searched: Medline, Embase, The Cochrane Library, and other important databases up to October 2009 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). RESULTS: We found 17 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. CONCLUSIONS: In this systematic review we present information relating to the effectiveness and safety of the following interventions: acetazolamide, descent versus resting, dexamethasone, gingko biloba, and slow ascent.
Murdoch D. Altitude sickness. Clinical Evidence 2010; 03:1209.
Substantive changes at this update
Acetazolamide for prevention One RCT added found that acetazolamide reduced the proportion of people who developed acute mountain sickness compared with placebo after rapid ascent from 1600 m to 4300 m. Categorisation unchanged (Beneficial).
Slow ascent (or acclimatisation) for prevention One small quasi-RCT added comparing ascent from 3730 m to 7546 m over 15 days (rapid ascent) versus over 19 days (slow ascent) found that climbers following the slow-ascent protocol had lower acute mountain sickness scores compared with those following the faster-ascent protocol. However, the RCT had methodological flaws (low follow-up at some assessments, and variations in protocol). Evidence reassessed at update. Categorisation changed to Likely to be beneficial by consensus (previously Beneficial by consensus).
Ginkgo biloba for prevention One systematic review added identified two RCTs (reported in one publication) meeting Clinical Evidence reporting criteria. The RCTs assessed the effects of two preparations of gingko biloba versus placebo for prevention of acute mountain sickness. The RCTs, which were of similar size, found different results. One RCT found that, compared with placebo, gingko biloba reduced the proportion of people who developed acute mountain sickness, whereas the second RCT found no significant difference between groups for the same outcome. Categorisation unchanged (Unknown effectiveness).
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Rated by doctors in Relevance Newsworthiness Tropical and Travel Medicine ***** ***** Public Health ****** *****