Surrogate outcomes
Many clinicians have assumed that early nutritional support is required for critically ill children and adults. Malnutrition is associated with poor outcomes and nutritional support can improve surrogate nutritional outcomes, such as immune function, wound healing, and measured proteins (Briassoulis 2001; Heyland 1998b). In adult studies, however, there is a poor concordance between nutritional markers and clinical outcomes (Koretz 2005). Although it seems intuitive that providing nutrition will be of benefit, because malnutrition is harmful, it does not necessarily follow that nutritional support during the first week of illness improves a critically ill patient’s outcome.