Critical Illness Scoring Systems: Sequential Organ Failure Assessment, Acute Physiology and Chronic Health Evaluation II, and Quick Sequential Organ Failure Assessment to Predict the Clinical Outcomes in Scrub Typhus Patients with Organ Dysfunctions

Background and aim: Scrub typhus (ST) is an acute infectious disease of variable severity caused by Orientia (formerly Rickettsia) tsutsugamushi. The disease can be complicated by organ dysfunctions and the case fatality rate (CFR) is approximately 15%, which further rises with the development of severe complications. We studied the clinical features of the ST and the performance of critical illness scoring systems (CISSs) - Acute Physiology and Chronic Health Evaluation (APACHE) II, sequential organ failure assessment (SOFA), and quick SOFA (qSOFA) in predicting the clinical outcomes in complicated ST (cST) patients admitted to the emergency department.

Study design and methods: A prospective observational study was done in 50 patients diagnosed to have cST with one or more organ dysfunctions. Clinical features and laboratory parameters were recorded and the patients were followed up until the end of their stay in the hospital. APACHE II, SOFA, and qSOFA scores at admission were calculated and were analyzed in predicting the clinical outcomes.

Results: The median SOFA, APACHE II, and qSOFA scores of the cohort were 7 (interquartile range [IQR] = 13-22), 8 (IQR = 5-11), and 2 (IQR = 1-3), respectively. The median duration of in-hospital stay was 9 (IQR 5-11) days and overall CFR was 8%. On bivariate analysis, both SOFA (P = 0.031) and qSOFA (P = 0.001) predicted mortality. However, only SOFA score correlated with the in-hospital stay duration (Pearson's correlation = 0.311, P = 0.028).

Conclusion: Among the three CISSs studied, the SOFA score correlated with in-hospital stay duration and mortality, whereas the qSOFA score formed a simple as well as a convenient tool in predicting the mortality in patients of cST with organ dysfunction.