Table 4.

Risk Factor Identification With Multivariate Analysis (31 Studies)^a

Risk factor	Associated with:	No. of studies and references
Demographic-related
Advanced age	Death; disease progression; unfavorable outcomesb; development of ARDS; myocardial injury; lower odds of hospital discharge	185,28,43,54,55,59,63,65,68,72,75,81,84,93,94,97,99,109
Male	Death; disease progression; development of severe respiratory failure; disease refractoriness	555,63,85,89,99
Symptom-related
Dyspnea	Death; development of critical illness	368,72,109
Hemoptysis	Development of critical illness	168
Unconsciousness	Development of critical illness	168
Anorexia on admission	Disease refractoriness	189
Fever on admission	A protective factor for disease refractoriness	189
Hypoxia	Death; disease progression; SpO2-FiO2 ratio negatively correlated with the incidence of ARDS	528,61,72,93,97
Comorbidity-related
Presence of any comorbidity (not specific)	Death; disease progression	428,54,63,81
No. of comorbidities	Development of critical illness	168
Hypertension	Death; disease progression; myocardial injury	443,55,60,97
Diabetes	Unfavorable outcomes	159
Cardiovascular disease (not specific)	Death	1106
Coronary heart disease	Death; myocardial injury	394,97,109
Chronic heart failure	Death; myocardial injury	243,94
Cardiac arrhythmia	Death	194
Cerebrovascular disease	Death	1109
COPD	Death; myocardial injury	343,94,106
Chronic renal failure	Myocardial injury	143
Cancer	Development of critical illness	168
Smoking	Death; unfavorable outcomes	259,94
Complication-related
ARDS	Death	1106
PE	Invasive mechanical ventilation	190
Organ dysfunction (not specific)	Death; development of ARDS	284,93
Critical disease status	Unfavorable outcomes	159
Laboratory-related
Leukocytosis	Unfavorable outcomes	159
Lymphopenia	Death; disease progression; higher lymphocyte count associated with decreasing mortality	528,60,62,81,93
Decreased CD4 cell count	Disease progression	161
Neutrophilia	Death; development of ARDS; unfavorable outcomes	359,84,97
Neutrophil- lymphocyte ratio	Disease progression	263,68
Elevated CRP	Death; development of critical illness; myocardial injury	443,60,65,97
Elevated procalcitonin	Death	1109
Elevated IL-6	Disease progression	252,56
Elevated AST	Death	297,109
Direct bilirubin	Development of critical illness	265,68
Elevated troponin	Death; cardiac ejection fraction (TTE); unfavorable outcomes	343,59,70
Elevated CK-MB	Death	143
Elevated LDH	Death; development of critical illness	665,68,75,81,93,97
Elevated D-dimer	Death; development of ARDS	35,84,97
Serum amyloid A	Disease progression	162
suPAR	Development of severe respiratory failure	185
Detectable serum SARS-CoV-2 viral load	Poor prognosis	152
GFR	Death; log hs-TnT was independently associated with estimated GFR	270,97
Higher BUN	Disease progression	165
Lower albumin	Disease progression	165
RDW	Disease progression	165
Imaging-related
Chest radiographic abnormality	Development of critical illness	168
Visual or software quantification of extent of CT lung abnormality	Predictors of ICU admission or death: %V-WAL <73%; %S-WAL <71%; VOLWAL <2.9 L	191
Severity score–related
High SOFA score	Death	25,20
High APACHE II score	Death	120
Treatment-related
ACEI/ARB	Log hs-TnT independently associated with the use of ACEI/ARB	170
Antiviral treatment	Lower odds of hospital discharge	175
Early time from illness onset to antiviral treatment	Improvement of prognosis	154
Administration of hypnotics	Protective effects on patient outcomes	159
Predictive models
Host risk score	Severe COVID-19: older age, male, presence of hypertension	155
Risk nomogram	Severe COVID-19: older age, higher LDH, CRP, RDW, DBIL, and BUN, and lower ALB	165
Clinical risk score (Web-based calculator)	Development of critical illness: chest radiographic abnormality, age, hemoptysis, dyspnea, unconsciousness, number of comorbidities, cancer history, neutrophil- lymphocyte ratio, lactate dehydrogenase, and direct bilirubin	168
CALL score	Disease progression: older age, comorbidity, lymphopenia, and increased LDH (>500 U/L)c	181
Clinical predictors	In-hospital mortality: age, history of hypertension and coronary heart disease	197
Laboratory predictors	In-hospital mortality: age, hs-CRP, SpO2, neutrophil and lymphocyte count, D-dimer, AST and GFR	197

^aACEI, angiotensin-converting enzyme inhibitor; ALB, albumin; APACHE, Acute Physiology and Chronic Health Evaluation; ARB, angiotensin receptor blocker; ARDS, acute respiratory distress syndrome; AST, aspartate aminotransferase; BUN, serum urea nitrogen; CALL, comorbidity, age, lymphocytes, and lactate dehydrogenase; CK-MB, creatine kinase myocardial band; COPD, chronic obstructive pulmonary disease; COVID-19, coronavirus disease 2019; CRP, C-reactive protein; CT, computed tomography; DBIL, direct bilirubin; FIO₂, fraction of inspired oxygen; GFR, glomerular filtration rate; hs-CRP, high-sensitivity CRP; hs-TnT, high-sensitivity troponin T; ICU, intensive care unit; IL-6, interleukin 6; LDH, lactate dehydrogenase; PE, pulmonary embolism; RDW, coefficient of variation of red blood cell distribution width; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; SOFA, Sequential Organ Failure Assessment; SpO₂, peripheral capillary oxygen saturation; suPAR, soluble urokinase plasminogen activator receptor; %S-WAL, software-based assessment of well-aerated lung percentage; TTE, transthoracic echocardiogram; VOLWAL, open-source software assessment of well-aerated lung absolute volume; %V-WAL, visual assessment of well-aerated lung percentage.

^bUnfavorable clinical outcome included death, progression, and/or maintenance of severity status.

^cSI conversion factor: To convert LDH value to μkat/L, multiply by 0.0167.