CI: Calorie/Energy Needs (2007)

Krishnan JA, Parce PB, Martinez, Dietz GB, Brower RG. Caloric intake in medical ICU patients: consistency of care with guidelines and relationship to clinical outcomes.  Chest 2003;124:297-305. PubMed ID: 12853537
Study Design:
Prospective Cohort Study
B - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

To assess the consistency of caloric intake with American College of Chest Physicians (ACCP) recommendations for critically ill patients and to evaluate the relationship of caloric intake with clinical outcomes.

Inclusion Criteria:
  • MICU patients
  • ICU LOS > 96 hours
  • Feb, 1999 – Oct, 2000
Exclusion Criteria:
  • Surgical, trauma or burn patients
  • Able to take PO within 96 hr
  • Transfer to other hospitals or ICUs
  • Do not resuscitate order within 96 hrs.
Description of Study Protocol:
Recruitment:  Data collected from MICU patient records in two hospitals 1) Johns Hopkins (JH) and 2) St. Agnes (SA) to determine whether or not caloric intake met recommendations of the American College of Chest Physicians (1997).

Design:  Retrospective cohort

Blinding used: not applicable

Intervention:  not applicable

Statistical Analysis:  Descriptive statistics (means, medians, and proportions); Kruskall-Wallis, X2 tests or Spearman correlation coefficients for bivariate analyses; and logistic regression models. Power analysis from pilot data indicating 50% mortality in MICUs indicated 180 patients (90 deaths) sufficient for conducting multivariate analyses (Hosmer-Lemeshow goodness-of-fit test). Two-tailed P value of < 0.05 defined statistical significance.
Data Collection Summary:
Timing of Measurements:
  • energy intake measured daily (EN and/or PN intake)

Dependent Variables:
  • mean percent caloric intake in ICU relative to guideline recommendations = (Total (each day's caloric intake/ACCP target each day))/number of ICU days
  • mortality (alive or dead at hospital discharge)
  • spontaneous ventilation (breathing without mechanical ventilation)
  • sepsis (ICU discharge without developing nosocomial invection)

Independent Variables:
  • age
  • markers of nutritional status (serum albumin level and BMI)
  • severity of illness (SAPS-II)
  • route of nutritional support (EN or PN)
  • Mean kcal intake/d relative to ACCP guidelines
    • 25 kcal/kg/d or 27.5 kcal/kg/d during SIRS
  • Mean intake categorized into tertiles
    • I=0-32% of goal
    • II=33-65% of goal
    • III=>66% goal
  • Presence of SIRS
    • Temp > 38 C or < 36 C
    • Heart rate > 80 bpm
    • Respiratory rate > 20 bpm
    • And WBC >12000 or < 4000 cells/mL
    • Hypocapnea requirement was omitted as all pts did not have ABG measurements daily.
  • Age, albumin SAPS II score
  • Route of feeding
  • Enteral always nasogastric tube
Description of Actual Data Sample:

Initial N:  187 (gender not described)

  • Johns Hopkins MICU n=141
  • St. Agnes Hospital MICU n=46

Attrition: not applicable

Age: significant difference in mean age between the two MICUs (P<0.0001)

  • JH patients mean age 48.8 years (39.0-64.3 years)
  • SA patients mean age 68.2 years (54.9 - 74.9 years)
  • mean age of both units: 50 years (41-62 years)

Ethnicity:  not reported


  • mean BMI 25.0 (19.7-30.4) kg/m2 (NS difference between units)
  • albumin level significantly different between MICUs P<0.0001): JH 2.6 (2.2-3.1) mg/dL; SA 3.9 (2.6-4.0) mg/dL
  • NS differences in mean BMI (25.0 (19.7-30.4) kg/m2 by unit
  • Illness severity measured by SAPS II (40-62)

Location: Baltimore, MD

Summary of Results:
Bivariate Analyses

  Tertile I
(0 to 32% Goal Energy)
Tertile II (33 to 65% Goal Energy)
OR (95% CI)
Tertile III
(66% or more of Goal Energy)
OR (95% CI)
After Multivariate Analyses
Hospital Discharge Alive
1.0  1.2 (1.15-1.29)
0.82 (0.70 to 0.94)  Tertiles I and I NS different.
Tertile III significantly more likely not to leave ICU alive if SAPS II > 50*
Spontaneous Ventilation (breathing without mechanical ventilation) 1.0 1.79 (1.42 - 2.24  0.69 (0.51 - 0.94)   
Sepsis (left ICU without nosocomial sepsis) 1.0  1.23 (0.75 - 2.00)
 0.75 (0.44 - 1.27)

  • Feeding began 2 days from ICU admission
  • Mean caloric intake not associated with route of feeding (EN vs PN) or SAPS II severity of illness measure or with markers of nuritional status on ICU admission (albumin level and body mass index)
  • Cumulative avg intake ­ over several days to 50.6% of AACP guidelines.
  • 69.7% fed enterally only, 19.5% fed both parenteral and enteral
  • * Multivariate analyses showed
    • likelihood of hospital discharge alive was no longer significantly different between tertiles II and of caloric intake; patients in Tertile III had significantly lower likelihood of both hospital discharge alive and spontaneous ventilation prior to ICU discharge
    • *patients with SAPS II of < 50, caloric intake NS associated with likelihood of hospital discharge alive
    • *patients with SAPS II of > 50, both Tertile II (OR 0.83; 95% CI, 0.77 to 0.90) and Tertile III (OR 0.46; 95% CI, 0.28 to 0.75)  associated with significantly lower likelihood of being discharged alive
Author Conclusion:

Study participants were underfed relative to ACCP targets. These targets, however, may overestimate needs, since moderate caloric intake (33-65% of ACCP targets or 9-18 kcal/kg/d) was associated with better outcomes than higher levels of caloric intake.

Funding Source:
University/Hospital: Johns Hopkins University School of Medicine, St Agnes HealthCare
Reviewer Comments:
Nice statistical treatment and report of findings
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? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
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? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
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? No
  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? Yes
  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? N/A
  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? Yes
  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.) Yes
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? Yes
  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? Yes
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? Yes
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? Yes
  6.6. Were extra or unplanned treatments described? Yes
  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? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? Yes
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? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  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)? Yes
  8.6. Was clinical significance as well as statistical significance reported? Yes
  8.7. If negative findings, was a power calculation reported to address type 2 error? Yes
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes