Meta Analysis
Does enteral nutrition compared to parenteral nutrition result in better outcomes in critically ill adult patients? A systematic review of the literature.
This review may be edited
Summary
Posted By: Gordon S. Doig
E-Mail: gdoig@med.usyd.edu.au
Posted Date: 6 Jan 2005
Title: Does enteral nutrition compared to parenteral nutrition result in better outcomes in critically ill adult patients? A systematic review of the literature.
Authors: Gramlich L, Kichian K, Pinilla J, Rodych NJ, Dhaliwal R, Heyland DK.
Reference: Nutrition. 2004 Oct;20(10):843-8.
Link: Click here for a direct link to the paper. A password may be required for access to fulltext.
Abstract: OBJECTIVE: Nutritional support is part of the standard of care for the critically ill adult patient. In the average patient in the intensive care unit who has no contraindications to enteral nutrition (EN) or parenteral nutrition (PN), the choice of route for nutritional support may be influenced by several factors. Because EN and PN are associated with risks and benefits, we systematically reviewed and critically appraised the literature to compare EN with PN the critically ill patient.
METHODS: We searched computerized bibliographic databases, personal files, and relevant reference lists to identify potentially eligible studies. Only randomized clinical trials that compared EN with PN in critically ill patients with respect to clinically important outcomes were included in this review. In an independent fashion, relevant data on the methodology and outcomes of primary studies were abstracted in duplicate. The studies were subsequently aggregated statistically.
RESULTS: There were 13 studies that met the inclusion criteria and, hence, were included in our meta-analysis. The use of EN as opposed to PN was associated with a significant decrease in infectious complications (relative risk = 0.64, 95% confidence interval = 0.47 to 0.87, P = 0.004) but not with any difference in mortality rate (relative risk = 1.08, 95% confidence interval = 0.70 to 1.65, P = 0.7). There was no difference in the number of days on a ventilator or length of stay in the hospital between groups receiving EN or PN (Standardized Mean Difference [SMD] = 0.07, 95% confidence interval = -0.2 to 0.33, P = 0.6). PN was associated with a higher incidence of hyperglycemia. Data that compared days on a ventilator and the development of diarrhea in patients who received EN versus PN were inconclusive. In the EN and PN groups, complications with enteral and parenteral access were seen. Four studies documented cost savings with EN as opposed to PN.
CONCLUSION: The use of EN as opposed to PN results in an important decrease in the incidence of infectious complications in the critically ill and may be less costly. EN should be the first choice for nutritional support in the critically ill.
 
Are the Results Valid?
1. Did the overview address a focused clinical question?
Yes. The authors addressed the question of PN vs EN in the critically ill adult patient.
2. Were the criteria used to select articles for inclusion appropriate?
Uncertain. Although the authors explicitly state that pseudo-randomised trials were excluded, the trial by Hadley et al is pseudo-randomised yet was included. Furthermore, the paper that was included by Moore et al is a meta-analysis. I am unaware of any methodological references that support the inclusion of a meta-analysis in a meta-analysis. The meta-analysis should have been decomposed into the published trials (Moore et al,Bower et al) that it is composed of. If each of these trials were appraised seperately, it is unlikely Bower et al would have qualified for inclusion in the primary analysis because it does not explicitly report mortality.
The trial by Kudsk et al also does not explicitly report mortality and should not have contributed to the primary analysis.
3. Is it unlikely that important, relevant studies were missed?
No. It is unlikely that important trials were missed.
4. Was the validity of the included studies appraised?
Yes, however since the reviewers failed to detect the fact that Hadley et al is pseudo-randomized, it is possible that other errors were made during the appraisal process.
5. Were assessments of studies reproducible?
Uncertain. The authors report that disagreements were resolved by consensus.
6. Were the results similar from study to study?
Based on an interpretation of the chi-square statistic, there is no evidence of heterogeneity. Calculation of the I2 measure reveals the presence of moderate heterogeneity (32%) in the primary analysis of mortality events. This would suggest that there may be true differences between studies such that the included trials should not be pooled.
What are the Results?
1. What are the overall results of the overview?
The use of EN as opposed to PN was not associated with any difference in mortality rate (relative risk = 1.08, 95% CI 0.70 to 1.65, P = 0.7).

When a subgroup of studies in which the PN group was fed more calories than the EN group were aggregated, EN was associated with a trend towards an excessive mortality compared with PN (RR 1.58, 95%CI 0.75 to 3.35, p=0.2).

EN was associated with a significant decrease in infectious complications (relative risk = 0.64, 95% confidence interval = 0.47 to 0.87, P = 0.004) .
2. How precise were the results?
See above for 95% CI.
Will the Results Help Me In Caring For My Patients?
1. Can the results be applied to my patient care
Yes. This review includes trials composed of heterogenous patient populations and low methodological quality. It suggests that PN use likely does not have a deleterious effect on mortality but may result in an increase in infectious complications. A subsequent meta-analysis, that included only well conducted trials, suggests that PN use may have a mortality benefit.
2. Were all clinically important outcomes considered?
Yes. The authors attempted to aggregate duration of ventilation, lenght of stay and costs.
3. Are the benefits worth the harms and costs?
Uncertain from this paper.

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Does enteral nutrition compared to parenteral nutrition result in better outcomes in critically ill adult patients? A systematic review of the literature.

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