Indicators of Acute Kidney Injury as Biomarkers to Differentiate Heatstroke from Coronavirus Disease 2019: A Retrospective Multicenter Analysis

• Published in: Journal of Nippon Medical School Vol. 88; no. 1; pp. 80 - 86
• Main Authors: Obinata, Hirofumi, Yokobori, Shoji, Ogawa, Kei, Takayama, Yasuhiro, Kawano, Shuichi, Ito, Toshimitsu, Takiguchi, Toru, Igarashi, Yutaka, Nakae, Ryuta, Masuno, Tomohiko, Ohwada, Hayato
• Format: Journal Article
• Language: English
• Published: Japan The Medical Association of Nippon Medical School 15.02.2021
• Subjects: Acute Kidney Injury - blood; Acute Kidney Injury - diagnosis; Acute Kidney Injury - etiology; Adult; Aged; Biomarkers - blood; C-Reactive Protein - analysis; Climate; coronavirus disease; COVID-19; COVID-19 - diagnosis; COVID-19 Testing; Creatinine - blood; Diagnosis, Differential; Female; Heat Stroke - blood; Heat Stroke - complications; Heat Stroke - diagnosis; heat-related illness; heatstroke; Hot Temperature; Humans; Leukocyte Count; machine learning; Male; Middle Aged; Predictive Value of Tests; Retrospective Studies; Seasons; Tokyo; Tokyo; COVID-19; heatstroke; coronavirus disease; machine learning; heat-related illness
• ISSN: 1345-4676; 1347-3409
• DOI: 10.1272/jnms.JNMS.2021_88-107

Background: Coronavirus disease 2019 (COVID-19) and heat-related illness are systemic febrile diseases. These illnesses must be differentiated during a COVID-19 pandemic in summer. However, no studies have compared and distinguished heat-related illness and COVID-19. We compared data from patients with early heat-related illness and those with COVID-19. Methods: This retrospective observational study included 90 patients with early heat-related illness selected from the Heatstroke STUDY 2017-2019 (nationwide registries of heat-related illness in Japan) and 86 patients with laboratory-confirmed COVID-19 who had fever or fatigue and were admitted to one of two hospitals in Tokyo, Japan. Results: Among vital signs, systolic blood pressure (119 vs. 125 mm Hg, p = 0.02), oxygen saturation (98% vs. 97%, p < 0.001), and body temperature (36.6°C vs. 37.6°C, p<0.001) showed significant between-group differences in the heatstroke and COVID-19 groups, respectively. The numerous intergroup differences in laboratory findings included disparities in white blood cell count (10.8 × 103/μL vs. 5.2 × 103/μL, p<0.001), creatinine (2.2 vs. 0.85 mg/dL, p<0.001), and C-reactive protein (0.2 vs. 2.8 mg/dL, p<0.001), although a logistic regression model achieved an area under the curve (AUC) of 0.966 using these three factors. A Random Forest machine learning model achieved an accuracy, precision, recall, and AUC of 0.908, 0.976, 0.842, and 0.978, respectively. Creatinine was the most important feature of this model. Conclusions: Acute kidney injury was associated with heat-related illness, which could be essential in distinguishing or evaluating patients with fever in the summer during a COVID-19 pandemic.