The FAO/WHO equation underestimated IC by 15.5% and the IOM equation underestimated by 19.1%, even though the latter uses the same variables as the Harris-Benedict equation
(weight, height and age), whereas the Schofield, Henry & Rees and FAO/WHO equations use age and weight as variables, which could contribute to making them less accurate.
Differences between measured RMR and RMR predicted by the other four equations--the Harris-Benedict (3), Mifflin (4), [Schofield.sub.weight] (6), and [Schofield.sub.weight and height] (6) equations--ranged from 159 kcal/day with the Mifflin equation to 225 kcal/day with the Harris-Benedict equation. The RMR predicted by these four equations differed by more than 10% from measured RMR for more than two-thirds of the young women included in this study.
The Harris-Benedict equation produced the largest mean difference from measured RMR and the greatest number of participants whose predicted RMR exceeded 10% of measured RMR.
However, three of the five PEs (the Owen, Mifflin, and Harris-Benedict equations) showed a systematic bias (p<0.05).
The equation uses actual weight, and notably it predicts significantly lower requirements when weight is very high, compared with the Schofield and Harris-Benedict equations. An advantage of the Mifflin-St Jeor equation (Table 3) is that it is very simple and easy to remember; however, like the Harris-Benedict equation, it requires values for both weight and height.
The studies that derived these injury factors have most commonly used the Harris-Benedict equation, and consequently it has been argued that the factors are not valid to use with other equations.
(51,52) In a number of studies of sedated mechanically ventilated patients, the Ireton-Jones equations performed better than other equations (including the Harris-Benedict equation), but did show some bias towards underestimation.