title: Comparison of a visual analogue scale and Lake Louise symptom scores for acute mountain sickness.
abstract: Assessment of the presence and severity of acute mountain sickness (AMS) is based on subjective reporting of the sensation of symptoms. The Lake Louise symptom scoring system (LLS) uses categorical variables to rate the intensity of AMS-related symptoms (headache, gastrointestinal distress, dizziness, fatigue, sleep quality) on 4-point ordinal scales; the sum of the answers is the LLS self-score (range 0-15). Recent publications indicate a potential for a visual analogue scale (VAS) to quantify AMS. We tested the hypothesis that overall and single-item VAS and LLS scores scale linearly. We asked 14 unacclimatized male subjects [age 41 (14), mean (SD) yr; height 176 (3) cm; weight 75 (9) kg] who spent 2 days at 3647 m and 4 days at 4560 m to fill out LLS questionnaires, with a VAS for each item (i) and a VAS for the overall (o) sensation of AMS, twice a day (n = 172). Even though correlated (r = 0.84), the relationship between LLS(o) and VAS(o) was distorted, showing a threshold effect for LLS(o) scores below 5, with most VAS(o) scores on one side of the identity line. Similar threshold effects were seen for the LLS(i) and VAS(i) scores. These findings indicate nonlinear scaling characteristics that render difficult a direct comparison of studies done with either VAS or LLS alone.
authors.affiliation: Institut des Sciences du Mouvement et de la Médecine du Sport, Université de Genève, Genève, Switzerland. bengt.kayser@unige.ch
authors.forename: Bengt
authors.initials: B
authors.lastname: Kayser
authors.forename: Andrea
authors.initials: A
authors.lastname: Aliverti
authors.forename: Riccardo
authors.initials: R
authors.lastname: Pellegrino
authors.forename: Raffaele
authors.initials: R
authors.lastname: Dellaca
authors.forename: Marco
authors.initials: M
authors.lastname: Quaranta
authors.forename: Pasquale
authors.initials: P
authors.lastname: Pompilio
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Miserocchi
authors.forename: Annalisa
authors.initials: A
authors.lastname: Cogo
mesh_terms: D000328:Adult; D000532:Altitude Sickness / Q000150:complications*; D006261:Headache / Q000209:etiology; D006801:Humans; D008297:Male; D012720:Severity of Illness Index