Table 1.

Data from 18 randomised trials on acute mountain sickness performed at 4050–5890 m and reporting absence of acute mountain sickness. Values are means (ranges)

Mode of ascentNo of trialsFinal altitude (m)Rate of ascent (m/h)Incidence (%) of acute mountain sickness with placebo
Climbing*64450 (4000–5356)91 (10–176)54 (25–79)
Transport plus climbing44963 (4050–5885)82 (34–156)65 (39–83)
Transport54647 (4300–5334)1268 (74–4400)73 (53–100)
Hypobaric chamber§34407 (4200–4570)1647 (179–4570)89 (75–100)
  • * Subjects walk to the final altitude.

  • † Subjects are first transported by car or cable car and then walk to the final altitude.

  • ‡ Subjects are transported to the final altitude by aeroplane, car, helicopter, or cable car.

  • § Subjects are placed in a chamber in which the atmospheric pressure can be decreased according to a study protocol.