Table 4.
Univariate and Multivariable Logistic Regression of Factors Associated with Acute Mountain Sickness on Day 2
| Predictors (n = 345) | Unadjusted OR (95% CI) | p | Adjusted OR (95% CI) | z | p |
|---|---|---|---|---|---|
| AMS on day 1 | 9.93 (5.61–17.60) | <0.001a | 12.88 (6.71–24.75) | 7.67 | <0.001 |
| Alcohol use | 2.82 (1.48–5.38) | 0.002a | 3.73 (1.66–8.39) | 3.18 | 0.001 |
| Age | 0.96 (0.93–0.98) | 0.002a | 0.96 (0.93,0.99) | −2.29 | 0.022 |
| Guide advice on day 1 | 0.62 (0.37–1.04) | 0.070a | 0.49 (0.26–0.93) | −2.17 | 0.030 |
| Guide advice on day 2 | 0.98 (0.58–1.67) | 0.943 | — | ||
| Gender male | 1.15 (0.68–1.95) | 0.598 | — | ||
| History of AMS | 0.58 (0.25–1.35) | 0.207 | — | ||
| High-altitude exposure in the past 2 months | 0.61 (0.20–1.82) | 0.375 | — | ||
| Duration of ascent (minutes)b | 1.00 (0.997–1.001) | 0.535 | — | ||
| Fitness levelc | |||||
| Unfit | (Ref.) | — | |||
| Average | 1.63 (0.59–4.48) | 0.343 | — | ||
| Fit | 1.48 (0.52–4.25) | 0.462 | — | ||
| Very fit | 0.9 (0.15–5.31) | 0.907 | — | ||
| Water intake on day 1 (L) | 1.06 (0.78–1.44) | 0.709 | — | ||
| Water intake on day 2 (L) | 1.35 (0.94–1.94) | 0.097a | — | ||
| Having sufficient-to-expert knowledge on AMS | 0.52 (0.30,0.92) | 0.024a | — | ||
| Acetazolamide use | 0.60 (0.27–1.34) | 0.214a | — | ||
Model fit indicator: likelihood ratio test (df) = 89.16 (4), p < 0.001; the Hosmer–Lemeshow χ2 test (df) = 12.78 (8), p = 0.120; AIC = 276.92; BIC = 296.14.
a
Variables with p-value <0.25 in univariate analysis are selected for stepwise forward method in multivariable logistic regression.
b
Time taken from Timpohon gate (starting point) to Laban Rata Basecamp (overnight location) on day 1.
c
Somewhat unfit and unfit were recategorized into one group because there was only one participant who was “somewhat unfit.”
AIC, Akaike's information criterion; BIC, Bayesian information criterion; OR, odds ratio.