Indicators of Acute Kidney Injury as Biomarkers to Differentiate Heatstroke from Coronavirus Disease 2019: A Retrospective Multicenter Analysis.
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.
['Obinata|Hirofumi|H|', 'Yokobori|Shoji|S|', 'Ogawa|Kei|K|', 'Takayama|Yasuhiro|Y|', 'Kawano|Shuichi|S|', 'Ito|Toshimitsu|T|', 'Takiguchi|Toru|T|', 'Igarashi|Yutaka|Y|', 'Nakae|Ryuta|R|', 'Masuno|Tomohiko|T|', 'Ohwada|Hayato|H|']
D058186:Acute Kidney Injury D000328:Adult D000368:Aged D015415:Biomarkers D002097:C-Reactive Protein D000086382:COVID-19 D000086742:COVID-19 Testing D002980:Climate D003404:Creatinine D003937:Diagnosis, Differential D005260:Female D018883:Heat Stroke D006358:Hot Temperature D006801:Humans D007958:Leukocyte Count D008297:Male D008875:Middle Aged D011237:Predictive Value of Tests D012189:Retrospective Studies D012621:Seasons D014041:Tokyo
heatstroke coronavirus disease COVID-19 heat-related illness machine learning