Performance of standard severity scoring systems for outcome prediction in patients admitted to a respiratory intensive care unit in North India

Abstract

Objective: There are little data on the value of using severity scoring systems developed in western countries to assess critically ill patients in India. The authors evaluated the performance of Acute Physiology and Chronic Health Evaluation version II (APACHE II), Simplified Acute Physiology Score version II (SAPS II) and Mortality Probability Models version II at admission and at 24 h (MPM(0) and MPM(24), respectively) in predicting patient outcomes in their Respiratory Intensive Care Unit.

Methods: Data from 459 consecutive adult admissions were collected prospectively. Standardized mortality ratios were computed as an index of the overall model performance. Model calibration was assessed using Lemeshow-Hosmer goodness-of-fit tests and through calibration curves. Model discrimination was assessed through receiver operating curve analysis and by drawing 2 x 2 classification matrices.

Results: Overall standardized mortality ratio exceeded 1.5 for all models. All models had modest discrimination (area under receiver-operating-characteristic curves 0.66-0.78) and poor calibration (high Lemeshow-Hosmer C and H statistic values). All models had a tendency to underpredict hospital death in patients with lower mortality probability estimates. There were no major differences between the models with regard to either discrimination or calibration performance.

Conclusions: Standard severity scoring systems developed in western countries are poor at predicting patient outcome in critically ill patients admitted to a respiratory intensive care unit in Northern India. Caution must be exercised in using such models in their present form on Indian patients until either they are customized for local use or fresh models are developed from Indian cohorts.