Study Addresses Nutritional Support Of Critically Ill Patients Interview with:
Sheila E. Harvey, Ph.D.
CTU Manager/Senior Research Fellow
Napier House London

Medical Research: What is the background for this study?

Dr. Harvey: The CALORIES trial was set-up in the context of concerns about malnutrition in critically ill patients in NHS hospitals and conflicting evidence as to the optimal route for delivery of early nutritional support to critically ill patients. The enteral route is the mainstay of nutritional support in the critically ill but it is frequently associated with gastrointestinal intolerance and underfeeding. In contrast, the parenteral route, though more invasive and expensive, is more likely to secure delivery of the intended nutrition but has been associated with more risks and complications (e.g. infectious complications) compared with the enteral route.

In light of the uncertainty surrounding the most effective route for delivery of early nutritional support and, given recent improvements in the delivery, formulation and monitoring of parenteral nutrition, the UK National Institute of Health Research (NIHR) Health Technology Assessment (HTA) Programme put out a “call” for a large pragmatic randomised controlled trial to be conducted in critically ill patients to determine the optimal route of delivery of early nutritional support. CALORIES was set up to test the hypothesis that early nutritional support delivered via the parenteral route is superior to early nutritional support delivered via the enteral route in adults who had an unplanned admission to an intensive care unit and who could be fed via either route.

The primary outcome was all-cause mortality at 30 days. The secondary outcomes included infectious and non-infectious complications (hypoglycaemia, elevated liver enzymes, nausea requiring treatment, abdominal distension, vomiting, new or substantially worsened pressure ulcers).

Medical Research: What are the main findings?

Dr. Harvey: Caloric intake was similar in the two groups, however, the target of 25 kcal/kg/day was not met in most patients. All-cause 30-day mortality was similar for patients allocated to receive early nutritional support via the parenteral route (33.1%) and via the enteral route (34.2%). The rates of hypoglycaemia and vomiting were significantly higher in the enteral route group. However, there was no significant difference between the groups in the mean number of treated infectious complications, or in any of the other secondary outcomes or in the rate of adverse events.

Medical Research: What should clinicians and patients take away from your report?

Dr. Harvey: The CALORIES trial evaluated delivery of early nutritional support via the parenteral compared with the enteral route, as typically administered in critical care units in NHS hospitals in England. The trial has demonstrated that previous beliefs about the risks of feeding patients via the parenteral route (e.g. infectious complications) have been shown not to be true in the present day in English intensive care units.  In addition, the assumption that early nutritional support delivered via the parenteral route automatically guarantees delivery of the intended nutrition was also shown not to be true. Longer-term follow-up of patients is ongoing and we await the cost-effectiveness analysis. The CALORIES trial did not address the question of nutritional dose, however the findings suggest that the choice of route for nutritional support can be determined by clinical need without concerns about potential major direct harm from either route.

Medical Research: What recommendations do you have for future research as a result of this study?

Dr. Harvey: The findings of the CALORIES trial suggest that early nutritional support via the parenteral route is neither more harmful nor more beneficial than early nutritional support via the enteral route. The question as to what is the optimal nutritional dose and the optimal method for determination of energy and protein or amino acid requirements for critically ill patients are important future research questions in this field.


Trial of the Route of Early Nutritional Support in Critically Ill Adults
Sheila E. Harvey, Ph.D., Francesca Parrott, M.Sci., David A. Harrison, Ph.D., Danielle E. Bear, M.Res., Ella Segaran, M.Sc., Richard Beale, M.B., B.S., Geoff Bellingan, M.D., Richard Leonard, M.B., B.Chir., Michael G. Mythen, M.D., and Kathryn M. Rowan, Ph.D. for the CALORIES Trial Investigators

N Engl J Med 2014; 371:1673-1684
October 30, 2014DOI: 10.1056/NEJMoa1409860