| Altitude | Mean ONSD* (95% CI) | p Value |
| 0 | 4.67 (4.45 to 4.89) | Ref |
| 2000 000 | 4.90 (4.67 to 5.13) | 0.12 |
| 3700 700 | 4.95 (4.72 to 5.18) | 0.06 |
| 5200 200 | 5.18 (4.96 to 5.41) | <0.001 |
| 6400 400 | 5.31 (5.03 to 5.60) | <0.001 |
| Per 1000 metre | 0.10 (0.05 to 0.14) | <0.001 |
| AMS score | ||
| 0 | 4.75 (4.58 to 4.91) | Ref |
| 1 | 5.12 (4.87 to 5.37) | <0.01 |
| 2 | 5.10 (4.85 to 5.35) | 0.02 |
| 3 | 5.24 (4.92 to 5.57) | <0.01 |
| 4+ | 5.29 (5.01 to 5.56) | 0.001 |
| Per unit AMS score | 0.12 (0.06 to 0.18) | <0.001 |
| Resting heart rate (beats/min)† | ||
| 1st quintile (56, 47 to 59) | 4.67 (4.43 to 4.91) | Ref |
| 2nd quintile (65, 60 to 71) | 4.79 (4.56 to 5.03) | 0.47 |
| 3rd quintile (77, 74 to 81) | 4.96 (4.72 to 5.20) | 0.10 |
| 4th quintile (89, 82 to 95) | 5.22 (4.98 to 5.47) | <0.01 |
| 5th quintile (106, 96 to 130) | 5.34 (5.10 to 5.59) | <0.001 |
| Per 20 beats/min | 0.29 (0.17 to 0.41) | <0.001 |
| Oxygen saturation (%)† | ||
| 1st quintile (67, 56 to 74) | 5.23 (4.98 to 5.48) | Ref |
| 2nd quintile (79, 75 to 82) | 5.25 (5.01 to 5.50) | 0.90 |
| 3rd quintile (86, 83 to 89) | 4.97 (4.74 to 5.21) | 0.13 |
| 4th quintile (94, 90 to 95) | 4.88 (4.59 to 5.16) | 0.06 |
| 5th quintile (97, 96 to 97) | 4.70 (4.51 to 4.90) | 0.001 |
| Per 10% increase | −0.20 (−0.29 to −0.11) | <0.001 |
AMS, acute mountain sickness; HR, heart rate; ICP, intracranial pressure; ONSD, optic nerve sheath diameter; Ref, reference value.
*Allowing for repeated measures in the same individual, and adjusted for age, sex, right and left eye, assessment of scan quality, whether the ocular lens was visible in the scan, and for three people who had returned to 6400 metres after an earlier climb.
†Numbers in parentheses in first column are mean, range.