How is the score calibrated

Criterion validity reflects the extent to which a descriptor accurately measures a phenomenon when compared with an existing gold standard. There is no discrete biochemical or pathophysiological marker of the presence of multiple organ dysfunction syndrome, and no independent method of gauging its severity. ICU mortality was chosen as the criterion against which variables were calibrated since it is accepted that multiple organ dysfunction syndrome is associated with a mortality whose magnitude is a function of the severity of the syndrome. However, this does not imply that a measure of organ dysfunction is a good predictor of mortality, as at least 20 per cent of all deaths in the ICU setting result from disorders other than the multiple organ dysfunction syndrome. ICU mortality, rather than hospital mortality, was selected to acknowledge that a patient capable of short-term survival without ICU support does not have life-threatening multiple organ dysfunction syndrome, even though he or she may have a terminal illness.

Once the methodological approach was defined, optimal descriptors were selected for organ dysfunction through a cohort study of 700 critically ill patients admitted to a surgical ICU in a tertiary care center. Dysfunction within each organ system was measured on a scale ranging from zero to 4 to provide maximal separation of increasing degrees of abnormality. Values of each variable were calibrated so that a score of zero represented normal function and predicted a mortality of 5 per cent or less, whereas a score of 4 reflected profoundly deranged function and correlated with a mortality of 50 per cent or greater. Intervening values of the variable were selected to provide sensible intervals of approximately comparable magnitude. A scale with five incremental increases allowed the final score to be sensitive to relatively small changes in function, yet the increments for each variable were sufficiently large for a one-point change in score to represent a significant change in function.

Healthy Fat Loss For A Longer Life

Healthy Fat Loss For A Longer Life

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