Table 1.

Characteristics of all patients at first presentation stratified according to their hospital admission status

		Hospitalization at first presentation			Not hospitalized at first presentation (n = 355)
Characteristics	Total (N = 1423)	Yes (n = 1068)	No (n = 355)	P-value	Returned for second presentation (n = 36)	Did not return for second presentation (n = 319)	P-value
Sex (male), %	61	62	56	0.06	64	55	0.33
Age (years), mean ± SD	64 ± 15	64 ± 14	64 ± 16	0.53	72 ± 14	63 ± 16	0.002
BMI (kg/m2), mean ± SD	27 ± 5	27 ± 5	27 ± 6	0.67	27 ± 4	27 ± 6	0.86
Race, %				0.05			0.93
Asian	3	3	4		6	4
Black or African descent	6	5	7		9	7
White or Caucasian	86	86	86		83	86
Other or unknown	5	6	3		3	3
Tobacco use, %				<0.001			0.001
Current	6	7	4		0	4
Prior	22	22	19		42	17
Never	45	47	39		42	39
Unknown	28	24	37		17	40
CFS (AU), mean ± SD	3.7 ± 1.8	3.7 ± 1.8	3.7 ± 1.7	0.74	3.9 ± 1.7	3.7 ± 1.8	0.44
Patient identification, %				<0.001			0.03
Symptoms only	73	75	66		85	64
Symptoms and contact	14	15	11		15	10
No symptoms but contact	5	5	6		0	6
Routine screening	8	5	17		0	20
COVID-19 test result, %
Positive	94	92	97		92	98
Negative	4	5	2		6	2
Intermediate/unknown	2	2	1		3	–
Abnormality on X-ray (yes), %	35	44	9	<0.001	14	8	0.03
Abnormality on CT scan (yes), %	32	41	6	<0.001	8	5	0.35
Comorbidities, %
Obesity	23	23	21	0.45	15	22	0.34
Hypertension	83	83	84	0.79	83	84	0.95
Diabetes mellitus	39	40	39	0.62	44	38	0.45
Coronary artery disease	29	30	28	0.50	33	27	0.44
Heart failure	19	21	14	0.007	17	14	0.68
Chronic lung disease	12	12	11	0.55	17	11	0.28
Active malignancy	6	7	3	0.01	8	3	0.08
Autoimmune disease	5	5	4	0.31	8	3	0.11
Primary kidney disease, %
Primary glomerulonephritis	16	16	13	0.12	14	13	0.81
Pyelonephritis	2	3	1	0.20	0	2	0.45
Interstitial nephritis	4	5	3	0.10	3	3	0.92
Hereditary kidney disease	10	10	12	0.24	9	12	0.53
Congenital diseases	2	2	3	0.26	0	3	0.28
Vascular diseases	13	12	14	0.47	17	14	0.55
Secondary glomerular disease	7	7	10	0.06	11	10	0.74
Diabetic kidney disease	21	22	19	0.27	34	17	0.02
Other	14	13	18	0.02	6	19	0.05
Unknown	10	11	8	0.09	6	8	0.63
Dialysis (yes), %	71	67	85	<0.001	78	86	0.19
HDa	99	99	99	0.29	100	99	0.57
PDa	1	1	1		0	1
Residual diuresis ≥200 mL/daya	32	33	31	0.002	46	29	0.006
Transplant waiting list statusa, %				0.001			0.12
Active on waiting list	11	11	10		7	11
In preparation	10	10	10		7	10
Temporarily not on list	9	10	7		4	6
Not transplantable	63	64	61		82	58
Unknown	7	5	13		0	15
Transplantation (yes), %	29	34	15		22	14
Time since transplantationb, %				0.12			0.04
<1 year	7	8	2		0	13
1–5 years	32	31	42		50	40
>5 years	61	61	57		38	60
Medication, %
ACE inhibitor use (yes)	16	17	14	0.32	19	11	0.007
ARB inhibitor use (yes)	16	15	19	0.12	22	15	0.014
Use of immunosuppressive medication, %
Prednisone	85	86	84	0.61	92	82	0.41
Tacrolimus	67	67	66	0.83	67	66	0.97
Cyclosporine	10	11	7	0.45	0	8	0.31
Mycophenolate	58	58	55	0.63	50	56	0.68
Azathioprine	4	4	4	0.82	0	5	0.44
mTOR inhibitor	12	12	11	0.81	17	10	0.49
Disease characteristics
Days from symptoms onset, median (IQR)	2 (0–4)	2 (0–5)	1 (0–3)	<0.001	1 (0–4)	1 (0–3)	0.28
Presenting symptoms, %
Sore throat	12	13	9	<0.001	17	8	0.04
Cough	53	58	38	<0.001	56	36	0.009
Shortness of breath	36	44	11	<0.001	22	10	0.005
Fever	62	68	44	<0.001	50	43	0.007
Headache	11	13	8	<0.001	14	8	0.006
Nausea or vomiting	12	13	7	<0.001	6	7	0.004
Diarrhoea	16	18	11	<0.001	14	10	0.008
Myalgia or arthralgia	21	23	16	<0.001	26	15	0.003
Vital signs, mean ± SD
Temperature (°C)	37.5 ± 1.1	37.6 ± 1.1	37.2 ± 1.0	<0.001	37.3 ± 1.2	37.2 ± 1.0	0.55
Respiration rate (per min)	20 ± 6	20 ± 6	17 ± 4	<0.001	17 ± 4	17 ± 3	0.85
O2 saturation room air (%)	94 ± 6	93 ± 6	97 ± 3	<0.001	97 ± 3	97 ± 3	0.60
SBP (mm Hg)	135 ± 25	135 ± 25	137 ± 24	0.14	129 ± 22	139 ± 25	0.04
DBP (mm Hg)	75 ± 15	76 ± 15	73 ± 15	0.05	69 ± 15	74 ± 15	0.07
Pulse rate (bpm)	84 ± 16	85 ± 16	77 ± 13	<0.001	73 ± 11	77 ± 14	0.13
Laboratory test results
Creatinine increase (>25%)b	30	33	8	<0.001	25	12	0.007
Lymphocytes (×1000/µL), median (IQR)	0.9 (0.6–1.3)	0.9 (0.5–1.3)	0.9 (0.6–1.2)	0.87	0.7 (0.5–1.1)	0.9 (0.6–1.2)	0.41
CRP (mg/L), median (IQR)	31 (8–84)	38 (10–95)	13 (3–43)	<0.001	26 (6–58)	12 (2–36)	0.02

Groups were compared using Student’s t, Wilcoxon or chi-square test as appropriate. Obesity is defined as BMI >30 kg/m². O₂, oxygen; SBP, systolic blood pressure; DBP, diastolic blood pressure; bpm, beats per minute; mTOR, mechanistic target of rapamycin.

^aIn dialysis patients only.

^bIn transplant recipients only.