Patient selection: ICU patient
Outcome: mortality
Parameter:
(1) serum osmolality in mOsm per kg water at ICU admission
X =
= 0.0415 * ((osmolality) – 329)
mortality based on univariate logistic regression =
= 1 / (1 + EXP((-1) * X))
Y =
= 0.09 * ((osmolality)-312)
mortality based on a non-linear regression with least squares model =
= 0.08 + (0.55 * (1 / (1 + EXP((-1) * Y))))
Interpretation:
• An osmolality greater than 300 mOsm per kg water indicates a high risk patient.
• A high risk patient can have an osmolality less then 300 mOsm per kg water.
Performance:
• The authors found that osmolality performed as well as or better than more complex models, with an area under the ROC curve of 0.73. Performance was better for short-term ICU stays (<= 5 days, AUC 0.76) than long-term (> 5 days, AUC 0.71).
