Study of Nepalese pilgrims challenges diagnosis of acute mountain sickness

A team co-directed by Dr. Michael Koehle used the Lake Louise Score Questionnaire on nearly 500 Nepalis. Their findings call the popular method of diagnosing acute mountain sickness into question. Photo: Michael Koehle.

A study led by University of British Columbia scientists calls into question a widely used method of diagnosing acute mountain sickness.

The Lake Louise Score Questionnaire has been used for more than two decades to determine if someone was suffering from acute mountain sickness (AMS), which strikes people at elevations above 2,500 metres. The lack of oxygen causes a spectrum of ailments, from headaches to vomiting to potentially fatal swelling of the brain or lungs.

The questionnaire, valued for its simplicity under austere conditions, asks people who are feeling ill at altitude to rate themselves in five areas – headache, nausea, weakness, dizziness and sleep quality.

A team co-directed by Dr. Michael Koehle, an associate professor in UBC’s Faculty of Medicine and the School of Kinesiology, used the questionnaire on nearly 500 Nepalis who hiked to a 4,380-metre-high lake for a religious festival. Nearly a third of them were diagnosed with AMS.

A statistical analysis of the results, published recently in the journal High Altitude Medicine & Biology, found that the sleep score did not coincide with the answers on the other four parts of the questionnaire. If sleep quality was removed from the questionnaire, the reliability of the overall score increased.

Including the sleep score in the questionnaire, Koehle says, could lead to some people being treated unnecessarily, and others not getting treatment they need – which usually consists of going down to lower elevations.

“Although people with AMS frequently do have trouble sleeping, that symptom can be affected by many other factors, including noise, comfort and the mild dehydration that often occurs at high altitude,” Koehle says. “And while the entire questionnaire is based on a self-assessment, rating the quality of your own sleep is particularly subjective. So I would recommend removing that from the questionnaire.”

Video: Acute mountain sickness and the Lake Louise Score (download video)

BACKGROUND | DIAGNOSING ACUTE MOUNTAIN SICKNESS

Competing questionnaires: The Lake Louise Score Questionnaire was created at an annual conference on hypoxia (low oxygen levels) held in Lake Louise, Alberta. Another tool for diagnosing AMS, called the Environmental Symptom Questionnaire III (ESQ III), covers 65 measurements or symptoms, but calculating that score is difficult without a computer. The ESQ III does not consider sleep quality.

A simple sum: The Lake Louise Score Questionnaire asks people to rate themselves on five criteria on a scale of zero to three, with zero meaning “normal” or “good,” and three meaning “severe” (or, in the case of sleeping, “could not sleep at all”). A person must have a score of one or higher on the headache question, and an overall score of three or higher to be diagnosed with AMS.

A simple cure: People with severe AMS can be given extra oxygen if it’s available. But the most reliable and easiest treatment is descending to lower elevations.

An annual pilgrimage: The study was conducted during a pilgrimage undertaken by as many as 20,000 Nepalis, most of whom live at 1,400 metres. Over a day or two, they walk to 4,380 metres, many of them clad only in saris and flip-flops.

Mountain medicine expert: Koehle sees patients at UBC’s Allan McGavin Sports Medicine Centre, and in addition to the usual gamut of ailments and injuries – muscle and joint aches, breathing problems, concussions and fatigue – he has developed a specialty in helping people who spend time at high elevation for trekking, mining exploration (mostly in the Andes of South America), or training for athletic competition.