Title: Performance of Acute Physiology and Chronic Health Evaluation (APACHE II) severity scoring system on the outcome of critically ill patient in ICU
Abstract:
Background: Clinical assessment of severity of illness is an essential component of medical practice to define critically ill patients, estimate their prognosis, help in clinical decision making, guide the allocation of resources, estimate the quality of care and predict the outcome of critically ill-patient in the intensive care units (ICUs). Acute Physiology and Chronic Health Evaluation II (APACHE II) model is one of the widely used scoring system to quantify disease severity and hospital mortality risk in critically ill patients in ICUs in developed world and less used in developing and low middle income countries like Nepal. As it has been developed in the west and its prognostic validity remains questionable, also our patient population and facilities are different, it needs to be validated in the Nepalese context.
Objectives: To evaluate the performance of the Acute Physiology and Chronic Health Evaluation (APACHE II) severity scoring system in the prediction of outcome of critically ill patient in intensive care units (ICUs).
Materials and Methods: A prospective, observational cohort study was carried out on 501 critically ill patients aged more than 18 years, of either gender, admitted to an adult Intensive Care Units (medical and surgical) of Chitwan Medical College Teaching Hospital, a tertiary care center in central part of Nepal, with hospital stay more than 24 hours. This study was carried out over twelve months from January 2022 and February 2023. The Ethical Review Board approved this study (Ref: NHRC- 2297/71/2022-PhD). The variables of APACHE II score were collected from the physiological, laboratory, and patient characteristics mentioned in the ICU scoring data sheet at 24 hours. The patients were followed up till discharge from ICU or death. The outcome measure was ICU mortality as survivor and non-survivor. The APACHE II score and predicted mortality was calculated using computer software programme. The performance of the model i.e., accuracy of the model was evaluated using discrimination and calibration respectively. Discrimination of the model was evaluated by calculating area under a receiver operating characteristic (ROC) curve, whereas Calibration of model was analyzed by calculating Standardized mortality ratio (SMR). Logistic regression analysis was also used to find out the relationship between a dichotomous dependent variable and continues independent variable.
Results: There were 501 patients, and their median age was 48.96 (IQR 65- 30; Minimum 18, Maximum 86) years. Male comprised 306 (61.1%) and female comprised 195 (38.9%) of the total number of patients. Of the 501 patients, 185 (36.9%) died and 316 (63.1%) survived. Accuracy of discrimination was assessed by the area under the receiver operating characteristic (ROC) curve. The area under the ROC of APACHE II score to the hospital mortality was 0.722 (p <.001; 95% CI, .676 -.767). The calculated Standardized Mortality Ratio (SMR) for the APACHE II was 0.87. Logistic regression describes the relationship between dichotomous dependent variable and continues independent variable. The odds ratio for APACHE II was (OR= .983; p=<.488; 95% CI, .936-1.032).
Conclusion: APACHE II has good discrimination and calibration as evidenced by area under curve and standardized mortality ratio. It was found that Acute Physiology and Chronic Health Evaluation (APACHE II) severity scoring systems to be of acceptable value to describe severity of illness and to estimate outcome in a group of critically ill patients. The results of this study add value and can aid critical care physicians, critical care nurses and relatives of critically ill patients in deciding on the probable outcome, quality care and management decisions.
Key words: APACHE II, critically ill, intensive care unit, mortality, outcome.
Audience Take Away Notes:
• Acute Physiology and Chronic Health Evaluation (APACHE II) severity scoring system helps in assessment of severity of illness in ICUs. Admission in ICU can be done on the basis of this severity scoring system. It helps in deciding better patient care decision in ICUs. Subject who has been diagnosed higher predicted mortality rate needs more vigilant monitoring and highly specialized nursing & medical care
• Severity scoring system helps in effective planning of care to meets the needs of critically ill patients and their families who have complex, multisystemic problems. It helps in decision making for nurse, physician and family members, provides prognosis and discharge decisions, measure overall ICU performance and can be used in clinical research
• Helps to examine and compare the quality of ICU care as reflected by patient’s outcome. Optimized distribution of medical, nursing and financial recourses is of crucial importance in the delivery of health care in ICUs, particularly in the developing and low middle income countries of the world
