Data sources
The demographic characteristics, clinical symptoms, laboratory data, and medications were extracted from electronic medical records. Laboratory data consisted of complete blood count; liver and renal function tests; examination of hemostasis parameters; measurement of high-sensitivity C-reactive protein, procalcitonin, lactate dehydrogenase, and creatine kinase serum levels; and erythrocyte sedimentation rate. The thresholds of these measures were given by our laboratory. The upper limits of normal serum creatinine in men and women were 104 μmol/l and 84 μmol/l, respectively. The upper limits of normal BUN in men with age <60, 60 to 80, >80 years were 8.0, 9.5, and 8.3 mmol/l, respectively. The upper limits of normal BUN in women with age <60, 60 to 80, >80 years were 7.5, 8.8, and 8.3 mmol/l, respectively. The data were reviewed by a trained team of physicians. Estimated glomerular filtration rate was calculated with the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation.25 The date of disease onset was defined as the day when the first symptom was noticed. The endpoint was the in-hospital death.