To air is human: altitude illness during an expedition length adventure race.

Objective: To calculate the incidence and prevalence of altitude illness (acute mountain sickness [AMS], high altitude pulmonary edema, and high altitude cerebral edema) during an expedition length adventure race and to determine factors contributing to its development as well as identify cases requiring medical treatment, withdrawal from the event, or both.

Methods: The Primal Quest Expedition Length Adventure Race was held in Colorado in July 2002. Sixty-two coed teams of four participated in the event. It began at an altitude of over 9500 feet, ascended to an altitude over 13,500 feet with a cumulative elevation gain of 69,400 feet, of which 40,000 feet occurred in the first 12 hours of the event. There was 138,800 total feet of altitude change during the event. All racers underwent a prerace medical assessment 24 hours before the start of the race and completed an Environmental Systems Questionnaire version 3-R (ESQ 3-R). Onsite medical staff provided treatment during the event. A standard medical encounter form was used to record all patient encounters including a presumed diagnosis and disposition.

Results: At the start of the race, the prevalence of altitude illness was 4.5%. The incidence of altitude illness requiring medical treatment during the race was 14.1% (AMS, 33 [13.3%]; high altitude pulmonary edema, 2 [.81%]) resulting in 4 (14.3%) of the 28 medical withdrawals from the race. There was no correlation between home altitude, prerace ESQ scores, and successful completion of the race.

Conclusions: Altitude illness occurs among participants in expedition length adventure races and contributes significantly to withdrawal from the event.