The Team

Meet the students who will be collecting the data at the Capanna Regina Margherita.

Philip van der Linde

Philip van der Linde

Medical Master's Student (VU)

"Hi! How great that you've made it all the way up here, to 4,554 metres. Between 8 and 15 August I'm your point of contact here in the hut."

"Just like you, I have an enormous passion for the mountains; alpinism and climbing have drawn me in ever since I was young. Now, as a student researcher, I get the chance to combine that passion with medical science in a truly unique way!"

"That is why I'd like to invite you to take part in our groundbreaking (and literally breathtaking) study on altitude sickness. Will you help make the mountains safer? Feel free to come and talk to me in the hut!"

Etienne Bertjens

Etienne Bertjens

Medical Clerkship Student (VU)

"My love for the mountains and for nature goes hand in hand with a fascination for the human body under exceptional conditions. What does altitude do to us? And how do we push our limits in a responsible way?"

"I'm looking forward to meeting you here, and I'm curious to hear what drives you to come to this place."

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Observational study · Summer 2026 · Completed

SAAS-10@CRM

Somatic Alertness and Acute Mountain Sickness: investigating sex differences in symptom reporting at the Capanna Regina Margherita (4,554 m)

4,554 m Altitude
N ≥ 480 Participants
9–12 min Per participant

Study completed

The data collection phase of SAAS-10@CRM has been completed and the researchers have left the hut.

We warmly thank all participants for their contribution to this study. We are especially grateful to the staff of the Capanna Regina Margherita for the exceptionally pleasant collaboration. We also thank the mountain guides for their involvement in the study and for pointing their clients towards participation.

NL EN DE IT FR
Monte Rosa · Italian Alps
Why this study?
The puzzle of altitude sickness and sex

Acute mountain sickness (AMS) is measured with questionnaires — what you feel and what you report. But if men and women perceive and report symptoms differently, are you measuring biology or perception?

Are women biologically more susceptible?

Some studies suggest a higher AMS prevalence in women, but the literature is contradictory. Hormonal and vascular sex differences may play a role — but that is only one possible explanation.

Or do they report differently?

Earlier IRT analyses on the Annapurna Circuit showed comparable scale functioning but a trend towards different reporting of gastrointestinal symptoms. Differences in perception could partly explain the "sex gap".

Somatic alertness as the key

We measure somatic alertness: the tendency to notice, interpret and report bodily signals. If this differs between men and women, it may help determine symptom scores.

Conceptual model
From hypoxia to symptom score

AMS scores are a composite signal. This model shows how physiology, perception and reporting style together determine the measurement outcome.

Hypoxic exposure

4,554 m hypobaric hypoxia, exertion, acclimatisation status

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Physiological response

SpO₂ decline, heart rate change, hyperventilation

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Somatic alertness

Monitoring, catastrophic interpretation, behavioural response (SAAS-10)

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Reported score

LLS total, AMS-C

♀♂ Biological sex may exert an influence at every level: physiology, perception and reporting
Study design
One measurement, maximum focus

Cross-sectional observational study. All measurements take place ≥ 4 hours after arrival at the hut, during the early phase of symptom development.

Location

Capanna Regina Margherita (4,554 m), Monte Rosa massif, Italian Alps. Europe's highest mountain hut, with a long research tradition in high-altitude medicine.

Timing

Assessment takes place ≥ 4 hours after arrival. This ensures a uniform exposure duration while capturing early symptom development.
Data collection: July – August 2026. Expected inclusion: 30–45 participants per day.

Design

Single-site, cross-sectional, observational. No intervention, no invasive procedures. One standardised measurement per participant.

Data

Electronic data collection via Castor EDC (GCP-compliant). Paper back-up in case of connectivity problems. Fully anonymised — no personal data are stored.
Measurement instruments
What do we measure?

A combination of demographic data, validated questionnaires and non-invasive physiological measurements (7–10 min per participant).

Background

General Questions

Essential baseline data: biological sex, age and previous experience in the mountains (acclimatisation history).

New

SAAS-10

Somatic Alertness at Altitude Scale. Measures the tendency to notice, interpret and report bodily signals.

AMS Score

Lake Louise Score

International standard for AMS. Scores headache, gastrointestinal symptoms, fatigue and dizziness.

Symptom profile

ESQ-III / AMS-C

Environmental Symptoms Questionnaire. Weighted calculation for cerebral altitude sickness symptoms.

Covariate

Borg RPE

Rating of Perceived Exertion. Separates exertion-related fatigue from hypoxia-related complaints.

Physiology

SpO₂ & HR

Peripheral oxygen saturation and heart rate via a Nonin clinical pulse oximeter on the finger.

Study population
Who can take part?

All adult mountaineers present at the Capanna Regina Margherita during the 2026 research season.

≥ 480 Recruitment target
30 / 70 Expected ♀/♂ ratio (%)
≥ 18 Minimum age (years)

Inclusion criteria

  • Present at the CRM (4,554 m)
  • Age ≥ 18 years
  • Assessment possible ≥ 4 hours after arrival
  • Informed consent given
  • Sufficient command of English for the questionnaires

Exclusion criteria

  • Age < 18 years
  • Insufficient English language proficiency
  • Severe AMS / suspected HACE or HAPE
  • Altered consciousness or ataxia
  • Previous participation this season
Procedure
What do you do as a participant?

Participation is straightforward, voluntary, and takes only 9–12 minutes. Everything takes place in the hut.

Step 1

Recruitment

The researcher explains what the study involves and asks whether you would like to take part

Step 2

Scan the QR code

Scan the QR code on the poster in the hut, or you will be approached by the researcher

Step 3

Informed consent

Read the information and give your consent digitally via Castor EDC

Step 4

Questionnaires

Complete the demographics, LLS, ESQ-III, BORG and SAAS-10 digitally (~9 min)

Step 5

SpO₂ & heart rate

Brief non-invasive measurement with a finger sensor (~2 min)

Statistical analysis
How do we analyse the data?

The primary analysis tests whether somatic alertness (SAAS-10) is associated with AMS severity, and whether this association differs between men and women.

Multivariable regression models

The primary inference is based on two parallel regression models for the continuous outcome measures of altitude sickness severity: the Lake Louise Score (LLS) and the AMS-C score.

These models test the association between somatic alertness (SAAS-10) and AMS severity, adjusted for pre-specified covariates: age, previous altitude experience, use of analgesics or acetazolamide, and physical exertion (Borg score).

Because the exact distribution of the outcomes will only be fully characterised after data collection, the definitive statistical method (generalized linear modeling) will be chosen on the basis of the observed data properties. The interaction term Sex × SAAS-10 formally tests whether the association between somatic alertness and reported symptoms differs between men and women.

Secondary: clinical diagnosis

Logistic regression for exceeding the diagnostic thresholds: LLS ≥ 3 + headache and AMS-C ≥ 0.7. Supportive, not primary inference.

Psychometrics: SAAS-10

First validation: exploratory factor analysis (polychoric correlations), internal consistency, and SAAS-8 sensitivity analysis (without reversed items 9 and 10).

Ethics & regulations

Conducted in accordance with the Declaration of Helsinki (2024), the Dutch Medical Research Involving Human Subjects Act (WMO), the GDPR and the Dutch GDPR Implementation Act (UAVG). Approval requested from the LUMC review committee.

Privacy

Fully anonymous — no name, no identifiable data. A unique, automatically generated participant ID. Once submitted, data can no longer be traced back.

Risks

No invasive procedures. No clinical interventions. Risk is negligible. Participation takes 9–12 minutes and must never delay medical care.

Open Science

Protocol pre-registered on OSF. Anonymised datasets will be made available after publication (CC BY-NC-SA 4.0).