Differences Between the "Chinese AMS Score" and the Lake Louise Score in the Diagnosis of Acute Mountain Sickness

Abstract

The Chinese AMS score (CAS) is used in clinical medicine and research to diagnosis acute mountain sickness (AMS). However, the Lake Louise Score (LLS) is the well-accepted standard for diagnosing AMS. The difference between the CAS and LLS questionnaires is that the CAS considers more nonspecific symptoms. The aim of the present study was to evaluate differences in AMS prevalence according to the LLS and CAS criteria. We surveyed 58 males who traveled from Chongqing (300 m) to Lhasa (3658 m) via the Qinghai-Tibet train. Cases of AMS were diagnosed using LLS and CAS questionnaires in a few railway stations at different evaluation areas along the road. We subsequently evaluated discrepancies in values related to the prevalence of AMS determined using the 2 types of questionnaires (CAS and LLS). The prevalence of CAS-diagnosed AMS indicated that the percentage of AMS cases among the 58 young men was 29.3% in Golmud, 60.3% in Tanggula, 63.8% in Lhasa, 22.4% on the first day after arrival in Lhasa, 27.6% on the second day, 24.1% on the third day, and 12.1% on the fourth day. The prevalence of LLS-diagnosed AMS in Golmud was 10.3%, 38% in Lhasa, and 6.9% on day 1, the prevalence in each station was lower than that as assessed by the CAS. Our experimental data indicate that AMS diagnoses ascertained using the CAS indicate a higher AMS prevalence than those ascertained using the LLS. Through statistical analysis, the CAS seems capable of effectively diagnosing AMS as validated by LLS (sensitivity 61.8%, specificity 92.7%).

FIGURE 1

Correlation between the CAS and the LLS in the diagnosis of AMS in Tanggula. The solid line represents the fitting trend between the CAS and the LLS. Open circles represent the CAS and the LLS scores of each participant. rho = 0.64, tau = 0.53, R² = 0.52, Pearson = 0.72, and P < 0.01. AMS = acute mountain sickness, CAS = Chinese AMS score, LLS = Lake Louise score.

FIGURE 2

Correlation between the CAS and the LLS in the diagnosis of AMS in Lhasa. The solid line represents the fitting trend between the CAS and the LLS. Open circles represent the CAS and the LLS scores of each participant. rho = 0.50, tau = 0.43, R² = 0.31, Pearson = 0.56, and P < 0.01. AMS = acute mountain sickness, CAS = Chinese AMS score, LLS = Lake Louise score.

FIGURE 3

Relationship between prevalence rates determined by the CAS and the LLS. (^a) P < 0.05: compared with Golmud, Tanggula, and day 1, day 2, day 3, and day 4, as assessed by the CAS. (^b) P < 0.05: compared with Golmud, Tanggula, and day 1, day 2, day 3, and day 4, as assessed by the LLS. CAS = Chinese AMS score, LLS = Lake Louise score.

FIGURE 4

Diagnostic accuracy of the CAS. Receiver-operator curves for AMS diagnosis using the CAS. The area under the ROC curve (95% CI) was 0.865 (0.759–0.971; P < 0.01), and the best cut-off score of CAS = 3.5 (Youden index was 0.667; sensitivity 76.5%; specificity 90.2%). AMS = acute mountain sickness, CAS = Chinese AMS score, CI = confidence interval, LLS = Lake Louise score.