Skip main navigation

New offer! Get 30% off one whole year of Unlimited learning. Subscribe for just £249.99 £174.99. New subscribers only. T&Cs apply

Find out more

Transfer Epidemiology

In this article we explore the need for transfers, and some of the epidemiological data available in transfer medicine.
The picture shows a patient on a stretcher with the pumps running

In this article, we introduce some of the data available on transfer medicine.

The COVID-19 pandemic showed just how important critical care transfer teams can be to decompress hospitals and keep ICUs afloat. The pandemic completely changed the scope of critical care transfers around the world – with unprecedented numbers of critically ill patients and overstretched hospitals and intensive care units there came a pressing need to move patients to get the care that they required.

Beyond the pandemic, around the world we continue to see more centralisation of specialist services and ongoing bed pressures. This coupled with a constant need for repatriation and armed conflict casualties worldwide naturally creates a role for transfer medicine.

But what do we really know about how many critically ill patient transfers are done?
It is challenging to obtain an accurate picture of international transfer epidemiology. Public systems are not the sole performers of transfers, with the armed forces, private transfer companies and repatriation services also contributing. Data is sparse but below we explore what is available.


  • A snapshot study in the UK examined the reasons for transfers out of emergency departments and found that:
    • 75% of transfers were for specialist clinical care
    • 22% were due to non-clinical reasons such as bed shortages
  • The study also found that most transfers were done outside the hours of 08:00 – 18:00 and that it was junior doctors who most commonly accompanied the patient rather than specialised transfer teams. Perhaps you’ve been a part of this with a story to share – comment below!
  • NHS England is currently addressing this problem and is commissioning transfer teams throughout the UK – something which is already in place in other countries like the Netherlands, Germany, Australia and New Zealand.


  • In 2016 approximately 1.6 million patients were transferred between hospitals in the USA
  • In a more specific example, we can see the effect of centralisation of services. Below is a section of a map of the US transfer network (and specifically the most central Dallas intensive care unit with its connections and transfers in 2005).
An illustrative nodal map of the ICUs in Dallas Texas which demonstrates the complexity of critical care services working on hub and spoke models with centralisation of services @ Iwashyna T et al, Med Care. 2009 July ; 47(7): 787–793
Hospitals are shown at their latitude and longitude in a simple Cartesian projection. Node size is proportional to centrality. Line darkness is proportional to the number of transfers passing between the two hospitals
  • You can see from this map that a patient’s need for escalation or de-escalation coupled with the differences in healthcare provision can lead to an incredibly complex network for patients.
  • As healthcare transfer providers with patient care at the centre of our practice we need to be able to get patients where they need to go safely and efficiently.


  • A German study from 2010 analysed 504 aeromedical repatriations retrospectively and looked at the medical speciality of patients needing transfer 5
  • Most frequent specialities were trauma, internal medicine and neurology. The most frequent diagnoses were femoral neck fractures, cerebrovascular accidents, and myocardial infarctions.
  • 78% of the transfers were carried out with an air ambulance, 12% in a scheduled aircraft with regular seating and 10% on a stretcher in a scheduled aircraft (with 1% in a patient transport compartment installed on board a scheduled aircraft). You will learn more about these and aeromedical transfers in Week 3.
What we can learn here is that transfer requirements and total numbers performed varies from country to country and region to region. Transfer and Critical Care Networks can be complex, depending on individual needs of populations, the healthcare services available and their architecture.

In this article we’ve seen some examples from high income countries, but patient transfers must also occur in completely different parts of the world, with different challenges. In the next article we introduce you to how transfer medicine works in East Africa.


This article is from the free online

A Journey Through Transfer Medicine

Created by
FutureLearn - Learning For Life

Reach your personal and professional goals

Unlock access to hundreds of expert online courses and degrees from top universities and educators to gain accredited qualifications and professional CV-building certificates.

Join over 18 million learners to launch, switch or build upon your career, all at your own pace, across a wide range of topic areas.

Start Learning now