Table 1.

Baseline characteristics of included studies for the association between liver scores and clinical outcomes in patients with COVID-19.

Author, year, country	Study design	Sample size	Population	Data source	Age, female	Liver score reported (outcomes)	Estimate effect	Adjustments
Xiang, 2020 [38], China	Retrospective cohort	267	COVID-19	Guangzhou No. 8 People's hospital	47, 54	FIB-4 (IMV)		Sex, hypertension, DM, heart diseases, liver diseases, kidney diseases, psychological disorders, time from admission to symptom onset date, D-dimer, and CRP
						<1.45	1
						1.45–3.25	4.18 (0.39–45.23)
						>3.25	10.16 (0.80–128.51)
						FIB-4 (severe COVID-19)
						<1.45	1
						1.45–3.25	4.63 (1.47–14.58)
						>3.25	11.92 (3.14–45.20)
Cristóbal, 2021[19] Spain	Retrospective cohort	214	COVID-19 admitted in ICU	Hospital General Universitario Gregorio Marañón	59, 28	FIB-4 (death)		Charlson comorbidity index, the acute physiology and chronic health evaluation II, and serum ferritin
						Per 1 unit	1.31 (0.99–1.72)
						Forns	1.41 (1.11–1.81)
Elfeki, 2021[16], USA	Retrospective cohort	373	COVID-19 with metabolic syndrome	UnityPoint Clinic or Hospital in the state of Iowa	62, 48	FIB-4 (death)		Type 2 DM and CKD
						<1.30	1
						1.30–2.67	1.52 (0.37–6.34)
						>2.67	2.22 (1.20–4.12)
						FIB-4 (hospitalization)
						<1.30	1
						1.30–2.67	1.67 (1.06–2.64)
						>2.67	0.96 (0.84–1.10)
Samaniego, 2021[31], Spain	Retrospective cohort	160	COVID-19	5 tertiary-level hospitals in the region of Madrid	55, 66	FIB-4 (severe COVID-19)		Hypertension, respiratory disease, and bilirubin, LDH acute C-reactive protein
						<1.30	1
						≥ 2.67	3.41 (1.30–8.92)
Li, 2021[32], USA,	Retrospective cohort	202	COVID-19	Two large academic centers in Boston, Massachusetts	58, 46	FIB-4 (death)		Sex, BMI, ethnicity, hypertension, diabetes, remdesivir use, and history of liver diseases, baseline troponin T, CRP, lymphocyte count, LDH, and D-dimer
						<2.67	1
						≥2.67	6.29 (2.10–18.80)
						Per 1 unit	1.63 (1.22–2.17)
Calapod, 2020[15], Romania	Prospective cohort	138	COVID-19 with type II DM	Bucharest Emergency University	66, 42	FIB-4 (severe COVID-19)		Sex, BMI, dyspnea, ferritin, CRP, AST, and ALT
						<1.30	1
						1.30–2.67	2.47 (1.01–7.63)
						>2.67	4.89 (1.34–12.3)
Forlano, 2020[18], USA	Retrospective cohort	193	COVID-19 with NAFLD	Imperial College Healthcare NHS Trust	66, 67	FIB-4 (death)		Male, presence of type 2 DM, hypertension, dyslipidemia
						<3.5	1
						≥3.25	1.07 (0.15–3.5)
Targher, 2021[37], China	Retrospective cohort	310	NAFLD	Four sites in Zhejiang province	48, 62	FIB-4 (severe COVID-19)		Sex, obesity, diabetes, and presence/absence of MAFLD
						No MAFLD	1
						<1.3	0.82 (0.30–2.24)
						≥1.3	2.95 (1.37–6.34)
						FIB-4 (severe COVID-19)
						Per 1 unit	1.90 (1.33–1.72)
						NFS (severe COVID-19)
						Per 1 unit	2.57 (1.73–3.82)
Park, 2020[33], South Korea	Retrospective cohort	1005	COVID-19	Five tertiary hospitals of Daegu	72, 54	FIB-4 (death)		DM, COPD, lymphocyte count, e-GFR, SIRS on admission
						<4.95	1
						≥4.95	2.78 (1.69–4.58)
Sterlin,2020[36], USA	Retrospective cohort	256	COVID-19	Virginia Commonwealth University Medical Center in Richmond	58, 45	FIB-4 (death)		DM, kidney, cardiovascular diseases, and respiratory diseases
						<2.67	1
						≥2.67	1.68 (1.19–2.38)
						FIB-4 (IMV)
						<2.67	1
						≥2.67	3.09 (1.38–6.93)
Rentsch, 2020[34], UK	Retrospective cohort	3,789	COVID-19	VA National Corporate Data Warehouse on Members of the VA Birt	65, 10	FIB-4 (hospitalization)		Race, CKD, COPD, DM, hypertension, vascular disease, ACEI/ARB, NASIDs, SBP, oxygen saturation, albumin, e-GFR, hemoglobin, white blood cell count, lymphocyte count, VACS index score#
						<1.45	1
						1.45–3.25	2.96 (1.69–5.17)
						>3.25	8.73 (4.11–18.56)
						FIB-4 (severe COVID-19)
						<1.45	1
						1.45–3.25	4.59 (1.72–12.22)
						>3.25	8.40 (2.90–24.28)
Yao, 2021[39], China	Retrospective cohort	342	RT-PCR	Hospitals of Jiangsu province		NFS (severe COVID-19) <−1.5 ≥−1.5	Ref. 11.05 (1.19,102.43)	Age, gender, BMI, hypertension, diabetes
Biliotti, 2020[29], Italy	Retrospective cohort	299	COVID-19	INMI Lazzaro Spallanzani	54	FIB-4 (ICU admission or death) <2.67 ≥2.67	Ref. 1.35 (1.04–1.75)	Presence of severe pneumonia, obesity, and C- reactive protein
Fu, 2020[40], China	Case-cohort	200	COVID-19	Second Affiliated Hospital of Anhui Medical University	50.7, NA	AST/ALT (death) per 1	3.22 (1.59, 6.56)	Total bilirubin, alanine aminotransferase, creatinine, urea nitrogen, uric acid, creatine kinase, myoglobin, lactate dehydrogenase, aspartate aminotransferase
Sarin, 2020[35], international	Retrospective cohort	228	COVID-19 with preexisting chronic liver disease	APASL-ACLF Research Consortium Registry Study	51,47	AST/ALT (death) per 1	1.4 (2.5–5.4)	Total bilirubin
Goel, 2020[30], USA	Retrospective cohort	551	COVID-19	St Luke's University Hospital	63, NA	AST/ALT (death) per 1	2.75 (1.63–4.65)	Age, hypertension, diabetes, heart failure, chronic kidney disease, malignancy, chronic pulmonary disease, and chronic liver disease, total bilirubin, and the inflammatory marker

COPD: chronic obstructive lung disease; CKD: chronic kidney diseases; NASIDs: nonsteroidal anti-inflammatory drugs; MAFLD, metabolic dysfunction-associated fatty liver disease; e-GFR, estimated glomerular filtration rate; ACEI/ARB: angiotensin converting enzyme inhibitor/ angiotensin receptor blocker; BMI, body mass index; DM: diabetes mellitus; SBP: systolic blood pressure; DBP: diastolic blood pressure; CRP: C-reactive protein; AST: aspartate aminotransferase; ALT: alanine aminotransferase. #The VACS Index score is a validated measure of physiologic injury combining age, aspartate and alanine transaminase, albumin, creatinine, hemoglobin, platelets, white blood cell count, hepatitis C status, and body mass index.