Validation of a modified apache II scoring system in predicting mortality in patients in the intensive care unit at the University Teaching Hospital,Lusaka-Zambia

Abstract

The major challenge of intensive care in Zambia is limited availability of resources. With the increase in the number of intensive care units in the country, a tool to evaluate and compare the standard of care across these units could be used to help direct resources and provide quality assurance. Prognostic scoring systems may provide such a tool. Currently UTH has no specific data collection or prognostic scoring systems in place. Due to lack of facilities to directly measure oxygen partial pressure and arterial pH in many of Zambia’s intensive care units, the APACHE II (Acute Physiology and Chronic Health Evaluation II) scoring system, one of the most commonly used prognostic critical care scoring systems, may not be feasible to undertake countrywide. This study aimed at assessing how a modified APACHE scoring system excluding blood gas analysis (i.e. no pH and PO2) compares to the full APACHE II scoring system. This was a prospective cohort study conducted at the UTH intensive care unit, where 51 patients were recruited with a mean age of 34 years. Clinical and physiological variables were collected in the first 24 hours of admission, and a score calculated for each scoring system. The primary outcome was mortality. Specificity and sensitivity for each scoring system was determined and compared. The area under receiver operating characteristic curve (AUROC) for the APACHE II was 0.78 (CI = 0.65–0.91, P = 0.01) and mAPACHE II 0.78 (CI = 0.66–0.91, P= 0.01). No significant difference between the two scoring systems was found. There was no significant difference between the areas under the two ROC curves for the standard APACHE II scoring system and mAPACHE II scoring system. This study suggests that the modified APACHE II may be an acceptable alternative to the full APACHE II scoring system.