CI: Enteral Nutrition vs. Parenteral Nutrition (2012)

Study Design:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To compare enteral nutrition (EN) to parenteral nutrition (TPN) with regard to adequacy of nutritional intake, septic and non-septic morbidity, and mortality.
Inclusion Criteria:
Patient must be = 18 years of age, require adjuvant nutritional support (inadequate oral intake for = 7 days).
Exclusion Criteria:
No exclusion criteria given for this study.
Description of Study Protocol:

All patients admitted between November 1995 and July 1998 to Scarborough Hospital who met the set criteria were entered into the study. Physician  caring for the patient was allowed to choose the mode of nutrition support at his discretion. Factors considered by physicians included patient condition, anticipated speed of recovery, and other intervention. Patients with permanent or temporary intestinal failure, or whom bowel rest was required were given TPN (group 1). If the patient had a functioning gastrointestinal (GI) tract, patient was given EN (group 2). Patients with reasonable doubt to their GI function were randomized to either TPN (group 3) or EN (group 4). Randomization occurred by drawing a numbered sealed envelope corresponding to the treatment group. At the study’s start, Body Mass Index (BMI) was calculated, serum albumin recorded, and nutritional risk index (NRI) calculated [(1.519 x serum albumin) + (0.417 x % usual body weight, UBW)]. Patients were then categorized as well nourished (>98.5), mildly/moderately malnourished (83.5 -98.5), or severely malnourished (<83.5). Physiological and operative Severity Score for the Enumeration of Morbidity and Mortality (POSSUM) was used as a comparative guide to severity of illness.

TPN patient (groups 1 & 3) were fed peripherally (PPN) through cyclical infusion with rotated access sites when possible. Poor peripheral access or patients with central venous catheter were fed via central route. PPN was given over 12 hour period, usually at night. Central feedings were fed continuously over 24 hour period in most patients.  Feeding goal was to provide 30 cal/kg/d non-protein energy and 9 gN/d. Intensive Care Unit (ICU) pts w/ nasogastric tube (NG-tube) received 5-10 mL/h of polymeric enteral feed and increased with patient tolerance.

EN feedings were administered through percutaneous endoscopic gastrostomy (PEG), surgically placed gastrostomy tube, or feeding jejunostomy. Feeding goal was 30 cal/kg/d non-protein energy and 9 gN/d provided by commercial formula (Osmolite).Feeding rate was increased by steps over 24-48 hour period. 

Feeding volume was recorded daily and expressed as percentage of target volume. If patient was switched to alternative feeding method due to clinical indications, patient was analyzed with original group to which they were allocated (intent-to-treat analysis).

Data Collection Summary:
Description of Actual Data Sample:

562 patients entered into study.

267 in TPN group 1; 231 in EN group 2; 64 patients were randomized (32 in TPN group 3 and 32 in EN group 4). Group 1 was mostly post-operative patients , group 2 mostly non-surgical patients , and no significant diagnosis differences between groups 3 and 4.

Summary of Results:
  • 31.2% of patients had lost = 10% UBW.
  • 44.5% were severely malnourished and 11.2% were well nourished based on NRI score.
  • 24.3% had BMI = 19.
  • Incidence of weight loss = 10% UBW and severe malnutrition were significantly higher in group 1 compared to group 2 (p < 0.001). No significant difference in groups 3 or 4.
  • Mean POSSUM score was significantly higher in group 2 than group 1 (p <0.001). No significant difference in groups 3 or 4.
  • Mean POSSUM of randomized groups (3 and 4) were significantly higher than nonrandomized groups (1 and 2) (p<0.001).
  • PPN was initially used in 100/299 from groups 1 and 3 (33.4%). Of these 34.0% were converted to central feeding due to inability to maintain adequate peripheral access.
  • Patients receiving EN 189/263 (71.9%) were fed by NG-tube.  30 (15.9%) required prolonged EN feeding and were converted to PEG feeding.
  • TPN groups had a significantly higher volume of feed expressed as percentage of target group 1 compared w/ 2 (93.8% vs 80.1%, p<0.001) and group 3 compared with 4 (96.7% vs 54.1%, p<0.001)
  • Significantly more patients in group 2 received less than 80% target compared to group 4 (62.5% vs 32.0%, p<0.01).
  • 29 (10.9%) of group 1 TPN and 5 (15.6%) of group 3 were changed to adjuvant EN (33 able to tolerate EN, 1 due to fluid overload, 1 due to inadvertent removal of central line, 1 due to deranged liver function tests).
  • 15 (6.5%) patients from group 2 and 10 (31.3%) from group 4 were converted from EN to TPN. Failure to tolerate EN was most common reason.
  • 35/267 patients deemed by physician to have inadequate GI function were converted to EN or oral diet w/in 5 days of starting TPN. 86.9% accuracy in assessment
  • 19/231 patients received EN <5 days because of failure to tolerate feeding (10 converted to TPN). 91.8% accuracy of assessment.
  • No significant differences in incidence of septic complications between EN and TPN.
  • Incidence of septic morbidity was higher in patients fed =10 days in group 1 (50.5% vs20.2%, p<0.001), group 2 (51.4% vs 20.5%, p<0.001), group 3 (73.3% vs 29.4%, p=0.01), group 4 (50% vs 26.9%, not significant).
  • Significantly higher incidence of non-septic complications associated with EN compared to TPN.
  • No patients died from TPN related complications. 1 EN death occurred from peritonitis following PEG placement.
Author Conclusion:

EN fails to provide sufficient nutrient intake because of GI intolerance and complications related to delivery mode. Incidence of non-septic morbidity is higher among EN pts compared with TPN patients. This study provides no evidence that TPN predisposes one to septic morbidity or that EN is protective. Feeding choice should be determined through clinical assessment of GI function and EN should be encouraged to the limit of patient tolerance. EN supplemented by TPN to fulfill protein and energy requirements may provide the best nutritional support in critically ill patients.

Funding Source:
Fresenius Kabi (Sweden)
University/Hospital: Scarborough Hospital (UK)
Reviewer Comments:

Difficult paper to abstract due to  research protocol and moderately defined selection criteria.

Showed few differences between feeding routes
Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? N/A
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? N/A
  1.3. Were the target population and setting specified? N/A
2. Was the selection of study subjects/patients free from bias? Yes
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? N/A
  2.2. Were criteria applied equally to all study groups? N/A
  2.3. Were health, demographics, and other characteristics of subjects described? N/A
  2.4. Were the subjects/patients a representative sample of the relevant population? N/A
3. Were study groups comparable? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? N/A
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) N/A
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? No
  4.1. Were follow-up methods described and the same for all groups? N/A
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) N/A
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? N/A
  4.4. Were reasons for withdrawals similar across groups? N/A
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? No
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) N/A
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? N/A
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? N/A
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments described? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? N/A
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? No
  7.1. Were primary and secondary endpoints described and relevant to the question? N/A
  7.2. Were nutrition measures appropriate to question and outcomes of concern? N/A
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? N/A
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? N/A
  7.5. Was the measurement of effect at an appropriate level of precision? N/A
  7.6. Were other factors accounted for (measured) that could affect outcomes? N/A
  7.7. Were the measurements conducted consistently across groups? N/A
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? N/A
  8.2. Were correct statistical tests used and assumptions of test not violated? N/A
  8.3. Were statistics reported with levels of significance and/or confidence intervals? N/A
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? N/A
  8.6. Was clinical significance as well as statistical significance reported? N/A
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? N/A
  9.2. Are biases and study limitations identified and discussed? N/A
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? N/A
  10.2. Was the study free from apparent conflict of interest? N/A