Table 1.

Characteristics of included studies.

Studya	Country	Sample size		Study design	Transplant recipients	Follow-up duration (days)	Definition of severity used	Definition of COVID-19 infection used	Adjusted variables
		Transplant recipients	Nontransplant controls
Arya [27]	America	58	14,975	Retrospective	38 kidney, 8 liver, 5 heart, 3 pancreases, 4 multiorgan transplants	184	ICU admission, mechanical ventilation	SARS-CoV-2 RT-PCR (+)	NR
Avery [19]	America	45	2427	Retrospective	NR	173	Invasive mechanical ventilation	SARS-CoV-2 RT-PCR (+)	NR
Caillard [8]	France	273	273	Retrospective	Kidney	64 (55–71)	Mechanical ventilation	SARS-CoV-2 RT-PCR (+)	Age, BMI, cardiovascular and respiratory diseases, cancer, and diabetes
Chaudhry [10]	America	35	100	Retrospective	38 kidneys and 9 non-kidney organs	35 (20–36)	ICU admission, mechanical ventilation	SARS-CoV-2 RT-PCR (+)	Age, coexisting conditions, transplant status, and Henry Ford Hospital COVID-19 severity score
Chavarot [17]	France	83	83	Retrospective	Kidney	13 (7–30)	defined as death and/or need for ICU	SARS-CoV-2 RT-PCR (+)	Age, sex, body mass index, diabetes mellitus, preexisting cardiopathy, chronic lung disease and basal renal function.
Fisher [23]	America	128	3907	Retrospective	106 kidneys, 9 livers, 6 hearts, 4 combined kidneys/pancreas, 3 combined kidney/livers	Patients were followed until the first of hospital discharge, death or September 1, 2020	ICU admission, mechanical ventilation	SARS-CoV-2 RT-PCR (+)	Age, sex, race, ethnicity, BMI, hypertension, diabetes mellitus, congestive heart failure, and obesity (defined as BMI ≥ 30 kg/m2).
Hardesty [25]	America	11	44	Retrospective	Kidney	80	NR	SARS-CoV-2 RT-PCR (+)	Age and sex
Linares [26]	Spain	41	220	Retrospective	32 kidney, 4 liver, 3 heart, 2 combined kidney/liver	80	ICU admission, mechanical ventilation	SARS-CoV-2 RT-PCR (+)	Age, sex, hypertension, lung disease, use of anti-cytokine therapies, baseline clinical status and clinical status during hospitalization
Miarons [9]	Spain	46	166	Retrospective	30 kidneys, 3 livers, 13 lungs	28	ICU admission	SARS-CoV-2 RT-PCR (+)	Sex, age and age-adjusted Charlson's Index
Molnar [11]	America	98	288	Retrospective	67 kidneys, 13 livers, 13 hearts, 4 lungs, and 1 pancreas	28	Invasive mechanical ventilation	SARS-CoV-2 RT-PCR (+)	Age, gender, race, ethnicity, BMI, comorbidities and medication use prior to hospital admission
Nair [24]	America	82	1625	Retrospective	69 kidneys, 3 livers, 6 hearts, 1 lung, 2 combined kidneys/pancreas, 1 combined kidney/liver	Patients were followed from the date of initial hospitalization until the first outcome of either death, discharge from the hospital, transfer to another center, or end of the study	Invasive mechanical ventilation	SARS-CoV-2 RT-PCR (+)	Age, gender, diabetes, hypertension, and cardiovascular disease (defined as any of coronary artery disease, peripheral arterial disease, or heart failure)
Ozturk [20]	Turkey	81	450	Retrospective	Kidney	28	ICU admission, mechanical ventilation	SARS-CoV-2 RT-PCR (+)	Age, gender, presence of diabetes, hypertension, cardiovascular disease, COPD and eGFR
Rinaldi [18]	Italy	24	861	Prospective	22 kidneys, 2 livers	30	ICU admission	SARS-CoV-2 RT-PCR (+)	NR
Ringer [22]	America	30	60	Retrospective	26 kidneys, 3 livers, 1 heart	28	Invasive mechanical ventilation	SARS-CoV-2 RT-PCR (+)	Age, BMI and comorbidities (hypertension and diabetes mellitus with hemoglobin A1c >8.0%)
Trapani [21]	Italy	450	238,875	Retrospective	285 kidneys, 89 livers, 54 hearts, 15 lungs, 8 pancreases	365	ICU admission, mechanical ventilation	SARS-CoV-2 RT-PCR (+)	Gender and age

^aAge data presented as median (IQR) or mean (SD); ICU: intensive care units; BMI: body mass index; COPD: chronic obstructive pulmonary disease; eGFR: estimated glomerular filtration rate; SARS-CoV-2: 2019 severe acute respiratory syndrome coronavirus 2; RT-PCR: Real-time reverse transcription polymerase chain reaction; NR, not reported.