Reliability And Utility of A Visual Analog Scale for The Assessment of Acute Mountain Sickness

Wagner, Dale R., Kevin Tatsugawa, Daryl Parker, and Troy A. Young. Reliability and utility of a visual analog scale for the assessment of acute mountain sickness. High Alt. Med. Biol. 8:27–31, 2007.—Acute mountain sickness (AMS) is a common condition that affects people that ascend too rapidly to high altitude. It is typically assessed with the Lake Louise AMS Self-report Score (LLSelf) that uses a categorical numeric rating scale to answer five questions addressing AMS-related symptoms, such as headache. A 100-mm visual analog scale (VAS) is commonly used to assess subjective phenomena such as pain, but this scale has never been used for the self-assessment of AMS. The purpose of this study was to compare a VAS score to the total LLSelf and to evaluate the test–retest and interrater reliability of the VAS when used as an assessment of AMS. Participants (N = 356) completed both the LLSelf and the VAS on the summit of Mt. Whitney (4419 m). There was a significant relationship (r = 0.65, p < 0.01) between the LLSelf (2.8 ± 2.0, mean ± SD) and the VAS (14.4 ± 14.1 mm). Fifty-seven participants were randomly selected for reliability testing of the VAS. Both test–retest reliability (ICC = 0.996, 95% CI = 0.992 to 0.998) and interrater reliability (ICC = 1.000, 95% CI = 0.999 to 1.000) were high. The mean difference in the VAS score between tests was <1 mm, as was the difference between raters. These results demonstrate excellent reliability for the VAS as an assessment of AMS.