Why Research Methodology Matters in Prehospital & Retrieval Medicine

In prehospital and retrieval medicine (PHRM), the way we design and interpret research can be just as important as the clinical interventions themselves. Poor methodology can obscure real benefits—or worse, make effective care appear ineffective.

Our latest explainer video focuses on immortal time bias, a common but frequently overlooked error in observational research. This bias occurs when studies condition inclusion on patients surviving to a later point in time, such as hospital arrival. In doing so, they exclude patients who die earlier and unintentionally distort outcomes.

This issue is particularly critical in PHRM. Many prehospital interventions provide benefit in two ways: by keeping patients alive long enough to reach the hospital and by increasing the total number of patients who ultimately survive. Studies that only include hospital arrivals fail to capture this first, essential benefit.

Using a simple visual example, the video demonstrates how identical treatments can appear dramatically different depending solely on when measurement begins. The takeaway is clear: to assess the effectiveness of prehospital care, outcomes must be measured from the point of injury or illness—typically the time of the call for help—not from hospital admission.

At Med Response BC, we believe improving methodological literacy is essential for clinicians, researchers, reviewers, and policymakers alike. Robust evidence starts with asking the right questions—and measuring from the right starting point.

🎥 Watch the full video to learn why methodology matters.