Validation of the APACHE‑II scoring system in critically ill patients diagnosed with COVID‑19 and admitted at a regional‑level hospital intensive care unit: A retrospective study.

Background: The use of the Acute Physiology and Chronic Health Evaluation II (APACHE-II) scoring system to predict mortality in the intensive care unit (ICU) has not been validated for use in the coronavirus-19 (COVID-19) pandemic in the South African context. Objectives: To provide data on the outcomes and clinical characteristics of ICU patients in a regional hospital diagnosed with COVID-19. The primary objective was to measure the validity of the APACHE-II scoring system in predicting mortality in these patients. Secondary objectives included the description of clinical characteristics, potential risk factors for mortality and length of ICU stay. Methods: This study was a single-centre, retrospective, observational cohort study conducted from 2020 to 2022. Data were obtained from electronic databases and patient records to determine diagnosis of COVID-19, demographics, comorbidities, history, clinical parameters and patient outcome. A receiver operating characteristic (ROC) analysis was performed to assess the discriminative power of the APACHE-II score in predicting mortality. Results: A total of 96 patients with confirmed COVID-19 diagnoses had sufficient data to calculate the APACHE-II score. The observed in-hospital mortality was 57.3%, while the APACHE-II score predicted a mortality of 25%. An ROC analysis showed poor discrimination (area under the ROC curve 0.58). Patients who had increased odds of death were those with increased age: odds ratio (OR) 1.01 (confidence interval (CI) 1.00 - 1.02), and those who were peripartum: OR 4.35 (CI 1.06 - 29.30). Other factors were not significantly associated with mortality. The median (interquartile range) length of hospital stay was 5.00 (4.00 - 9.25) days. Conclusion: The APACHE-II scoring system is a poor discriminator between death and survival in this cohort of COVID-19 ICU patients. ICU patients who were diagnosed with COVID-19 were more likely to die despite a relatively low APACHE-II score. Information regarding clinical characteristics of these ICU patients and their outcomes provides some insight into the nature of the COVID-19 pandemic. Contribution of the study: While mortality prediction models such as the APACHE-II score are valuable in general ICU populations, their applicability to novel diseases may be limited, as evidenced during the COVID-19 pandemic. Our findings highlight the limitations of these generalized prognostic tools when applied to future emerging diseases.