Table 4.

Summary of the related studies.

Study	Patients (n)	Model/algorithm	Cohort survival	Prediction	Area under the receiver operating characteristic curve	Feature importance
Pan et al [20]	123	XGBoost	52.8%	Mortality	0.86-0.92	Lymphocyte percentage, prothrombin time, lactate dehydrogenase, total bilirubin, eosinophil percentage, creatinine, neutrophil percentage, and albumin level
Gong et al [9]	372	Nomogram	99.7%	Severity	0.85 (95% CI 0.790-0.916)	Higher lactate dehydrogenase, C-reactive protein, red blood cell distribution width, direct bilirubin, blood urea nitrogen, and lower albumin
Ko et al [21]	375	XGBoost	98.1%	Mortality	—,a accuracy of 92%	Not assessed
Abdulaal et al [22]	398	Artificial neural network	—	Mortality	—, accuracy of 86% (95% CI 75%-93%)	Altered mentation, dyspnea, age, collapse, gender, and cough
Shi et al [10]	487	Custom risk score calculation	100%	Severity	—	Advanced age, presence of hypertension, and being male
Gao et al [8]	2160	Ensemble model based on logistic regression, gradient-boosted decision tree, neural network, and support vector machine	88%	Mortality	0.92-0.98	Consciousness, chronic kidney disease, lymphocyte counts, sex, sputum, blood urea nitrogen, respiratory rate, oxygen saturation, D-dimer, number of comorbidities, albumin, age, fever, and platelet count
Vaid et al [11]	4098	XGBoost	83%	Mortality	0.84-0.88	Age, anion gap, C-reactive protein, lactate dehydrogenase, oxygen saturation, blood urea nitrogen, ferritin, red cell distribution width, and diastolic blood pressure.
Kim et al [23]	4787	XGBoost	—	Need for intensive care	0.88-0.89	Activities of daily living, age, dyspnea, body temperature, sex, and underlying comorbidities
Bolourani et al [24]	11,525	XGBoost	—	Predicting respiratory failure	0.77	Invasive mode of oxygen delivery being a nonrebreather mask, emergency severity index values of 1 and 3, maximum respiratory rate, maximum, oxygen saturation, Black race, age on admission, eosinophil percentage, serum sodium level, and serum lactate level.
This study	11,807	GRU-D	95.4%	Mortality	0.938 cross-validation; 0.901 prospectively	Figure 2, top 5: age, Charlson comorbidity index, minimum oxygen saturation, fibrinogen level, and serum iron level

^aNot available.