Letter to the Editor: Sensitivity and Specificity of the Lake Louise Score: What Should We Focus On?

To the Editor:

In 1991, prominent high-altitude medicine and physiology experts came together and devised a self-reported research tool that could aid in screening acute mountain sickness (AMS) (Hackett and Olez, 1992). The tool was named the Lake Louise score (LLS) and had five components: headache, gastrointestinal (GI) upset, fatigue/weakness, dizziness/lightheadedness, and sleep disturbance. With scores 0 to 3 for each component, we can categorize AMS into mild, moderate, and severe AMS, which could guide how it is managed in some of the remotest of the places on earth.

It also had clinical assessment tools with changes in mental status, ataxia, and peripheral edema as the components and an AMS clinical functional score. This LLS was adopted by travelers and physicians as a screening tool for travelers going to high altitudes.

In 2018, an LLS revision was made with the removal of sleep disturbance as a component (Roach et al., 2018), citing evidence that sleep disturbance is discordant with other symptoms, based on a study done in 2013 among pilgrims ascending from 1,900 m altitude to 4,400 m in 1 to 2 days (Macinnis et al., 2013). A 2020 article also argued that the fatigue/weakness component also decreases the specificity of the LLS (Moore et al., 2020), based on a 2012 study done in adolescents at lower altitudes (Dallimore et al., 2012).

The possibility of future studies arguing for the removal of either of the remaining components cannot be dismissed as there are many confounding factors to GI upset (e.g., travelers' diarrhea, hypoxic suppression of appetite, or other medical causes of GI problems). As well, there are also many confounding causes for dizziness/lightheadedness.

The LLS was developed as a screening tool for AMS and not a confirmatory tool. It is designed to follow the progression of the disease to guide further travel at high altitude. Even though the LLS was designed as a research tool, it is being used by clinicians to screen for AMS, which has likely saved many lives. It is difficult to quantify how many lives this application of LLS has saved, but clinicians working at high altitude or clinicians who work with high-altitude travelers appreciate the impact LLS has made in the lives of people.

Removal of the LLS components decreases the sensitivity of the tool even though it may increase its specificity. A decrease in sensitivity will increase the number of false negatives while screening for AMS, which will have the effect of increasing the danger of AMS at high altitude that, in most parts of the world, are resource limited and hard to leave easily when anyone becomes ill.