Association between an increase in blood urea nitrogen at 24 h and worse outcomes in COVID-19 pneumonia

Figures & data

Table 1. Outcomes in patients with delta BUN increase versus no increase at 24 h.

	No increase	Increase
Delta BUN (N = 266)
Transfer to Intensive care unit	28 (13.6)	23 (38.3)	p<.001
Invasive mechanical ventilation	12 (5.80)	18 (30.0)	p<.001
Acute kidney injury	7 (3.40)	13 (21.7)	p<.001
All-cause mortality	12 (5.80)	18 (30.0)	p<.001
Normal admission BUN (N = 217)
Transfer to Intensive care unit	15 (8.8)	13 (27.7)	p<.001
Invasive mechanical ventilation	4 (2.4)	8 (17.0)	p<.001
Acute kidney injury	1 (0.6)	6 (12.8)	p<.001
All-cause mortality	4 (2.4)	8 (17.0)	p<.001
Abnormal admission BUN (N = 49)
Transfer to Intensive care unit	12 (33.3)	11 (84.6)	p<.001
Invasive mechanical ventilation	8 (22.2)	10 (76.9)	p<.001
Acute kidney injury	5 (13,9)	8 (61.5)	p<.001
All-cause mortality	7 (19.4)	10 (76.9)	p<.001

Table 2. Odds ratios for death case associated with BUN Increase in whole population and in different subgroups.

	Model1			Model2			Model3
	OR	(95% CI)	p	OR	(95% CI)	p	OR	(95% CI)	p
Total	6.391	(2.845,14.360)	<.001	5.964	(2.565,13.867)	<.001	7.427	(2.370,23.279)	.001
Subgroups
Admission BUN
<20 mg/dL	7.262	(2.027,26.018)	.002	6.475	(1.697,24.700)	.006	4.235	(1.011,17.746)	.048
≥20 mg/dL	11.667	(2.576,52.845)	.001	19.879	(3.225,122.539)	.001	111.116	(3.359.,3675.461)	.008
Hypertension
Yes	3.750	(1.322,10.637)	.013	3.984	(1.341,11.832)	0.013	6.342	(0.890,45.209)	.065
No	10.937	(2.933,40.782)	<.001	12.179	(3.049,48.641)	<.001	12.223	(2.437,61.317)	.002

Model1: unadjusted.

Model2: adjusted for age, gender, hypertension, COPD, and respiratory rate.

Model3: adjusted for age, gender, hypertension, COPD, respiratory rate, LYM, ALB, and GLO.

OR odds ratio: CI confidence interval: COPD chronic obstructive pulmonary diseases: LYM lymphocyte: ALB albumin: GLO globulin.

Table 3. Analysis by Cox regression of death during hospitalization.

Variable	HR	95%CI	p
Signal-Factor Regression Analysis
Age, years	1.009	(0.983, 1.037)	.498
Gender, male	1.005	(0.483, 2.092)	.99
Comorbidities
Hypertension	2.038	(0.957, 4.338)	.065
Diabetes mellitus	1.868	(0.799, 4.372)	.149
Coronary heart disease	1.995	(0.850, 4.680)	.112
COPD	1.585	(0.477, 5.267)	.452
At Admission
Systolic blood pressure, mm Hg	1.004	(0.982, 1.031)	.6
Diastolic blood pressure, mm Hg	1.712	(0.777, 3.769)	.182
Heart rate, beats per minute	1.025	(1.001, 1.050)	.04
Respiratory rate, beats minute	1.031	(1.004, 1.058)	.025
Temperature, °C	1.613	(0.815, 3.192)	.17
O2 saturation, %	0.919	(0.954, 1.006)	.106
Admission Laboratory Examination
Creatinine (mg/dL)	1.009	(1.005, 1.014)	p<.001
RBC, *1012 /L	0.834	(0.508, 1.370)	0.473
Hemoglobin, g/dL	0.994	(0.980, 1.009)	0.44
WBC, *109 /L	1.01	(0.985, 1.035)	0.434
LYM, *109 /L	0.128	(0.048, 0.343)	p<.001
Neutrophil, *109 /L	1.079	(1.036, 1.122)	p<.001
Albumin, g/L	0.836	(0.778, 0.898)	p<.001
Globulin, g/L	0.979	(0.891, 1.076)	.66
ALT, U/L	0.99	(0.976, 1.005)	.192
AST, U/L	0.999	(0.998, 1.000)	.166
D-dimer, ng/mL	1.138	(1.052, 1.232)	.001
CRP, mg/L	1.011	(1.006, 1.016)	p<.001
Admission Coagulation Function Analysis
PT, s	1.031	(0.985, 1.080)	.186
APTT, s	1.027	(1.005, 1.048)	.013
TT, s	1.204	(1.102, 1.316)	p<.001
PLT, *109 /L	0.99	(0.985, 0.995)	p<.001
FIB, g/L	0.84	(0.514, 1.373)	.488
INR	1.395	(0.790, 2.466)	.251
BUN Increase in 24 h	6.838	(3.150, 14.846)	p<.001
BUN at admission ≥20 mg/dL	5.881	(2.719, 12.718)	p<.001
Multiple-Factor Regression Analysis
Respiratory rate, beats minute	1.031	(1.004, 1.058)	.039
BUN Increase in 24 h	6.838	(3.150, 14.846)	.001
BUN at admission ≥20 mg/dL	5.881	(2.719, 12.718)	.017

COPD: chronic obstructive pulmonary disease; RBC: read blood cell; WBC: white blood cell; LYM: lymphocyte; ALT: alanine aminotransferase; AST: aspartate aminotransferase; CRP: C-reactive protein; PT: Prothrombin time; APTT: activated partial thromboplastin time; TT: thrombin time; PLT: platelet; FIB: fibrinogen; INR: international normalized ratio.

Figure 1. Cumulative incidence for in-hospital death of patients with coronavirus disease 2019 subgrouped by BUN value at admission and BUN change in 24 h. (A) Increase BUN versus no increase BUN at 24 h. (B) Increase BUN versus no increase BUN at 24 h when BUN at admission was normal (<20 mg/dL). (C) Increase BUN versus no increase BUN at 24 h when BUN at admission was abnormal (≥20 mg/dL).

Data availability statement

The data sets supporting the results of this article are included within the article. Some data used during the study are available from the corresponding author by request.