Does enteral nutrition affect clinical outcome? A systematic review of the randomized trials.

BACKGROUND: Both parenteral nutrition (PN) and enteral nutrition (EN) are widely advocated as adjunctive care in patients with various diseases. A systematic review of 82 randomized controlled trials (RCTs) of PN published in 2001 found little, if any, effect on mortality, morbidity, or duration of hospital stay; in some situations, PN increased infectious complication rates.
OBJECTIVE: The objective was to assess the effect of EN or volitional nutrition support (VNS) in individual disease states from available RCTs.
DESIGN: We conducted a systematic review. RCTs comparing EN or VNS with untreated controls, or comparing EN with PN, were identified and separated according to the underlying disease state. Meta-analysis was performed when at least three RCTs provided data. The evidence from the RCTs was summarized into one of five grades. A or B, respectively, indicated the presence of strong or weak (low-quality RCTs) evidence supporting the use of the intervention. C indicated a lack of adequate evidence to make any decision about efficacy. D indicated that limited data could not support the intervention. E indicated either that strong data found no effect, or that either strong or weak data suggested that the intervention caused harm. PATIENTS AND SETTINGS: RCTs could include either hospitalized or nonhospitalized patients. The EN or VNS had to be provided as part of a treatment plan for an underlying disease process.
INTERVENTIONS: The RCT had to compare recipients of either EN or VNS with controls not receiving any type of artificial nutrition or had to compare recipients of EN with recipients of PN. OUTCOME MEASURES: These were mortality, morbidity (disease specific), duration of hospitalization, cost, or interventional complications. SUMMARY OF GRADING: A: No indication was identified. B: EN or VNS in the perioperative patient or in patients with chronic liver disease; EN in critically ill patients or low birth weight infants (trophic feeding); VNS in malnourished geriatric patients. (The low-quality trials found a significant difference in survival favoring the VNS recipients in the malnourished geriatric patient trials; two high-quality trials found nonsignificant differences that favored VNS as well.) C: EN or VNS in liver transplantation, cystic fibrosis, renal failure, pediatric conditions other than low birth weight infants, well-nourished geriatric patients, nonstroke neurologic conditions, AIDS; EN in acute pancreatitis, chronic obstructive pulmonary disease, nonmalnourished geriatric patients; VNS in inflammatory bowel disease, arthritis, cardiac disease, pregnancy, allergic patients, preoperative bowel preparation. D: EN or VNS in patients receiving nonsurgical cancer treatment or in patients with hip fractures; EN in patients with inflammatory bowel disease; VNS in patients with chronic obstructive pulmonary disease. E: EN in the first week in dysphagic, or VNS at any time in nondysphagic, stroke patients who are not malnourished; dysphagia persisting for weeks will presumably ultimately require EN.
CONCLUSIONS: There is strong evidence for not using EN in the first week in dysphagic, and not using VNS at all in nondysphagic, stroke patients who are not malnourished. There is reasonable evidence for using VNS in malnourished geriatric patients. The recommendations to consider EN/VNS in perioperative/liver/critically ill/low birth weight patients are limited by the low quality of the RCTs. No evidence could be identified to justify the use of EN/VNS in other disease states.