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Table 3 Accuracy of the methods used to assess EE, expressed as bias, precision, and accuracy and inaccuracy rates

From: Ventilator-derived carbon dioxide production to assess energy expenditure in critically ill patients: proof of concept

  Bias Precision Accuracy quantified
  Mean difference in kcal/day, 95% CI Mean difference (% of gold standard EE) SD of bias (Levene’s F-testa) Bland–Altman limits of agreement Accuracy rates Inaccuracy rates
      <10 % <15 % >25 % >30 %
Method         
EE:VCO2 b +141, +107 to +174 7.7 % 153 −166 to +447 61 % 79 % 2 % 0 %
EE:HBc +246 13.5 % 263 −722 to +280 31 % 52 % 13 % 5 %
−303 to −189 p < 0.001 (F 14.1)   p = 0.001 p < 0.001 p < 0.002 p < 0.01
p < 0.001
EE:Esp25d +156, 8.6 % 344 −531 to +843 40 % 56 % 25 % 14 %
+81 to +230 p = 0.709 (F 31.1)   p = 0.009 p = 0.002 p < 0.001 p < 0.001
p < 0.001
EE:Faisye +176, 9.7 % 218 −260 to + 612 45 % 61 % 17 % 12 %
+129 to +233 p = 0.226 (F 9.0)   p = 0.01 p = 0.003 p < 0.001 p < 0.001
p = 0.003
EE:PSUf −22, 1.2 % 254 −529 to +458 54 % 75 % 10 % 6 %
−77 to +33 p < 0.001 (F 11.9)   p = 0.341 p = 0.582 p = 0.05 p = 0.023
p < 0.001
Post hoc calculation         
EE:HB15g −10 0.5 % 257 −524 to +504 55 % 71 % 10 % 6 %
−66 to +46 p < 0.001 (F 12.3)   p = 0.435 p = 0.285 p = 0.05 p = 0.023
p < 0.001
  1. EE energy expenditure, EE:Esp25 energy expenditure calculated with the European Society for Clinical Nutrition and Metabolism guideline equation of 25 kcal/kg/day, EE:Faisy energy expenditure calculated with the Faisy equation, EE:HB15 energy expenditure calculated with the Harris–Benedict equation with 15 % added, EE:PSU energy expenditure calculated with the Penn State University 2003b equation, EE:VCO 2 energy expenditure from ventilator-derived volume of carbon dioxide and nutritional respiratory quotient, HB Harris–Benedict equation
  2. Less than 10 % and less than 15 % accuracy rates represent the proportion of patients for which EE:VCO2 (or equation-based EE) predicted EE within 10 % and within 15 %, respectively, of gold standard EE:Calorimetry. Greater than 25 % and greater than 30 % inaccuracy rates represent the proportion of patients for whom EE:VCO2 (or equation-based EE) differed by more than 25 % and more than 30 %, respectively, from gold standard EE:Calorimetry
  3. All p values are relative to EE:VCO2.
  4. F-test and p value reflect the comparison of the variance of the mean difference of EE:VCO2 and EE from equations. The higher the F-value, the higher the difference of the variances. p < 0.05 indicates that the variance of the mean difference is significantly different from EE:VCO2.
  5. aLevene’s F-test on similar variances
  6. Bias: b vs. c p < 0.001; b vs. d p = 0.709; b vs. f p = <0.001; b vs. e p < 0.001; b vs. g p = 0.226; c vs. d p < 0.001; c vs. f p < 0.001; c vs. e p < 0.001; c vs. g p < 0.001; d vs. f p = 0.001; d vs. e p < 0.001; d vs. g p = 0.652; f vs. e p = 0.762; e vs. g p < 0.001