The APACHE 3 Prognostic System Risk Prediction of Hospital Mortality in Critically Ill Hospitalized Adults in Medical Intensive Care Unit on Mechanical Ventilation in Tertiary Care Center

Abstract

Background: Critically ill patients requiring mechanical ventilation have substantial morbidity and mortality, necessitating reliable tools for severity assessment and outcome prediction. The Acute Physiology and Chronic Health Evaluation III (APACHE III) scoring system incorporates physiological variables, age, and chronic health conditions to estimate hospital mortality. Materials and Methods: A prospective observational study was conducted among 120 patients requiring mechanical ventilation in the 10-bedded intensive care unit (ICU) of New Civil Hospital, Surat, from May 2018 to October 2019. Demographic characteristics, indications for ventilation, ventilator-related parameters, comorbidities, clinical findings, and laboratory investigations were recorded. The worst physiological parameters during the first 24 h of ICU admission were used to calculate the APACHE III score. Predicted mortality was calculated using the APACHE III mortality equations and compared with observed hospital mortality. Results: The majority of patients were aged 18–30 years (48.3%), and 77% were male. Neurological conditions were the most frequent broad indication for mechanical ventilation (67%), with organophosphorus (OP) poisoning being the most common individual diagnosis (50%). Most patients required ventilation for 1–7 days (60%). Overall, 48 patients (40%) died, whereas the mean predicted mortality was 32% and the mean APACHE III score was 62. Higher APACHE III scores were significantly associated with increased mortality (χ2 = 72.018, P < 0.001). A significant association was also observed between mortality and comorbidities (P < 0.001) and PaO2 levels (P < 0.001). Among patients with OP poisoning, APACHE III score was strongly associated with mortality (χ2 = 21.071, P < 0.001). Conclusion: APACHE III demonstrated good prognostic utility and effectively stratified mortality risk among mechanically ventilated ICU patients. Higher scores were strongly associated with increased observed mortality, supporting its use for outcome prediction in critically ill patients.