Immunonutrition for Prophylaxis of Postoperative Complications in Elective Surgery: A Systematic Review of Randomised, Controlled Clinical Trials

Rationale: There is increasing evidence that pre-, peri- and postoperative immunonutrition appears to decrease infectious complications (IC) and hospital length of stay (LOS) in patients undergoing major elective surgery, which is still associated with a high rate of postoperative morbidity. Surgery-induced alterations of the immune system may play a role in postoperative complications. Several nutrients have been shown to modulate immunologic and inflammatory responses in humans. The purpose of this systematic review was to evaluate whether these effects translate into improved clinical outcome.

Methods: A systematic review and a meta-analysis of randomised clinical trials was performed evaluating the effects of immunonutrition given to patients before and/or after major elective surgery. Studies were identified through a MEDLINE search, the authors' files, bibliographies of review articles, abstracts and proceedings of scientific meetings. Studies were assessed baseline characteristics, intervention, outcome and overall quality through blinded review. The primary endpoints were ICs, anastomotic leaks, mortality and hospital LOS.

Results: We identified 18 studies (n=2331), 15 published and 3 unpublished, of which 11 (n=1418) examined the effects of immunonutrition in a pre- or perioperative setting. Oral immunonutrition was given 5–7 days prior to surgery with an intake of 0.5–1L/day. 7 studies (n=913) dealt with postoperative application only. In all but one study the immunonutritional product investigated was a composite of the immunmodulating nutrients arginine, omega-3 fatty acids from fish oil and nucleotides (IMPACT®, Novartis Consumer Health, Nyon, Switzerland). Most studies (15) involved patients undergoing gastrointestinal surgery. The use of immunonutrition was associated with a statistically significant reduction in postoperative ICs overall (RR, 0.49: 95% CI, 0.42–0.58, p<0.0001), as well as anastomotic leaks (RR, 0.56: 95% CI, 0.38–0.83, p=0.003) and was also associated with a significant decrease in LOS (ES, –1.04: 95% CI, –1.45 to –0.63, p<0.0001) resulting in a reduction of LOS by 2.5 days (95% CI, –3.8 to –1.3). With respect to mortality, immunonutrition had no significant effect.

Conclusions: Immunonutrition significantly reduces postoperative ICs and anastomotic leaks in patients undergoing major elective surgery. This effect is associated with a significant reduction in hospital LOS. Immunonutrition, in particular when applied preoperatively, can now be considered a form of prophylaxis against postoperative morbidity.