Incidence and predictors of acute mountain sickness among trekkers on Mount Kilimanjaro

We investigated the incidence of AMS amongst a general population of trekkers on Mount Kilimanjaro, using the Lake Louise consensus scoring system (LLS). Additionally we examined the effect of prophylactic acetazolamide and different ascent profiles. Climbers on 3 different ascent itineraries were recruited. At 2743 m we recruited 177 participants (mean age 31, range [18-71]) who completed LLS together with an epidemiological questionnaire. At 4730 m participants (n=189, male=108, female=68, mean age 33, range [1871]) completed LLS, 136 of whom had been followed up from 2730 m. At 2743 m, 3% (5/177) of climbers were AMS positive, and 47% (89/189) of climbers from all itineraries were AMS positive at 4730 m. Of climbers attempting the Marangu itineraries, 33% (45/136) were taking acetazolamide. This group had a similar rate of AMS and no statistical difference in severity of LLS when compared with those not taking prophylactic drugs. We also did not demonstrate a difference between the incidence of AMS in climbers who did or did not take a rest day at 3700  m. However, there was a significant reduction in the incidence of AMS amongst pre-acclimatized subjects. Consistent with previous work, we found that the rate of AMS on Mount Kilimanjaro is high. Furthermore, at these fast ascent rates, there was no evidence of a protective effect of acetazolamide or a single rest day. There is a need to increase public awareness of the risks of altitude sickness and we advocate a pragmatic "golden rules" approach (http://www.altitude.org/altitude_sickness.php).