Predictors of mortality in a medical intensive care unit

Scoring systems to predict mortality in intensive care units have been developed in western populations. There is a need to identify and validate prognostic variables in the Indian context. We compared two scoring systems to predict the discharge outcome in patients admitted to a medical intensive care unit.

Five hundred patients admitted to a medical intensive care unit were studied prospectively. Modified acute physiology and chronic health evaluation II (APACHE II) score and modified organ system failure (OSF) score were applied on the day of admission to the intensive care unit. The scores obtained by the two systems were compared using the area under the curve approach. The likelihood ratios were calculated for predicting discharge outcome.

The modified OSF score predicted discharge outcome better than the modified APACHE II score--receiver operating characteristic curve area (standard error-area) 0.7062 (0.0244) and 0.6068 (0.0267) for the modified OSF and the modified APACHE II scores, respectively. This was statistically significant (p < 0.001). The likelihood ratio for the modified OSF score for different cut-off points varied from 0.27 to 5.49, while the likelihood ratio for the modified APACHE II score varied from 0.11 to 2.08. This means that for an intensive care unit with a 30% overall mortality, the modified OSF score could separate patients with 10% to 70% mortality, while the modified APACHE II score could predict only 5% to 47% mortality.

The modified OSF score was superior to the modified APACHE II score in predicting mortality in patients admitted to the medical intensive care unit.