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 ascent	No of trials	Final altitude (m)	Rate of ascent (m/h)	Incidence (%) of acute mountain sickness with placebo
Climbing*	6	4450 (4000-5356)	91 (10-176)	54 (25-79)
Transport plus climbing†	4	4963 (4050-5885)	82 (34-156)	65 (39-83)
Transport‡	5	4647 (4300-5334)	1268 (74-4400)	73 (53-100)
Hypobaric chamber§	3	4407 (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.