In the second model, the outcome measure was the cardinal symptom of AMS: high altitude headache[26]; in the third logistic model, the outcome was AMS defined by Lake Louise diagnosis (as is also often investigated in hypoxia research).[16] To determine whether predictor variables were consistent with being causally related to AMS, the first two models were rerun using a temporal time-lag technique. This involved the predictor variables at time-point t − 1 day high throughput screening compounds being related
to the outcome variable of AMS at time-point t and allowed determination of sequential temporality (ie, did the predictor variable change before the outcome variable?). All statistical analyses were completed using SPSS version 18 (IBM Corporation, NY, USA), and statistical significance was accepted at p < 0.05. A sample size estimation conservatively assuming the use of a five-height repeated measures experiment indicated that 22 participants would be needed to produce a 90% chance of obtaining statistical significance at the 0.05 level for a difference between the INCB024360 order most extreme heights of 0.7 standard deviations, a medium dispersion of height means, and an average correlation of 0.6 among the repeated measures.[27] The demographic and clinical data for the 44 analyzed participants are presented in Table 1. All medical conditions were well controlled and symptom free at the time of the expedition’s
departure. All participants were encouraged to continue normal medications, but altitude-specific prophylaxis/medications were discouraged. Arterial oxygen saturations are shown in Figure 2 and reveal decreased arterial oxygen saturations from a height of 2,081 m. The lowest mean value was 79.0% ± 4.4% at 5,050c m. Fluid intake consumed from drink bottles also decreased as height was gained (F = 7.173, p < 0.001). Total fluid intake was 70 ± 18 mL/kg/d at 1,100 m and 48 ± 18 mL/kg/d at 4,700 m. Symptoms
of diminished physical and mental health are described in Figures 3 and 4. Lake Louise symptom scores increased from the second day at 3,612 m and remained elevated until the third day at aminophylline 5,050 m (Figure 3). Nineteen of 44 individuals (43%) had clinically defined AMS while above 2,476 m. The AMS maximum symptom score on any one day was 95 (from a possible range of 0–660) and occurred on the second day at 4,670 m. The peak incidence of clinically defined AMS was 11 of 44 participants, which occurred twice (on the second day at 4,670 m and on the first day at 5,050 m). The rate of AMS per 100 person days was 9.2 (95% CI: 7.2–11.7), and the average length of illness was 2.8 days (2.2–3.4 d). On the second day at 4,670 m when the maximum daily burden of AMS symptoms occurred, the total Lake Louise score comprised the following individual symptoms: difficulty sleeping (28%), headache (27%), fatigue (19%), gastrointestinal upset (16%), and dizziness (10%) (Figure 3).