MRINZ-led Mega‑ROX Trial Hits 40,000 Participants in the World’s Largest ICU Study

We’re thrilled to announce a major milestone for the Mega‑ROX trial, led by Professor Paul Young and the MRINZ Critical Care team. The trial has now reached 40,000 participants, making it the world’s largest study in intensive care.

Mega‑ROX is exploring how different oxygen therapy strategies affect critically ill patients who require unplanned mechanical ventilation. The trial compares conservative oxygen therapy, with lower oxygen targets, against liberal oxygen therapy, with higher oxygen delivery. It also includes nested sub-studies for patients with sepsis, acute brain injuries, and patients who are unconscious after a cardiac arrest, helping clinicians worldwide understand which approach to oxygen therapy works best for different people.

The main focus of the trial is in-hospital mortality, while secondary outcomes look at how long patients spend on ventilators, their stay in ICU and hospital, and whether they return home. By involving tens of thousands of patients across the globe, the trial is helping shape ICU care worldwide, providing evidence to guide safer, more effective oxygen therapy for critically ill patients everywhere.

Professor Paul Young, MRINZ Deputy Director and Critical Care programme lead, says, "Enrolling 40,000 people was only possible because of an extraordinary global collaborative effort. I would like to acknowledge all of the people involved in conducting this trial who united with a common purpose of improving the outcomes of critically ill patients through high quality research."

This achievement reflects the dedication of the research team, the support of 137 ICUs across 14 countries, and the generosity of the patients and families who took part. Each of these 40,000 participants plays a vital role in advancing critical care and bringing the global ICU community one step closer to evidence-based improvements in patient outcomes.