Role of B-type natriuretic peptide as a marker of mortality in acute kidney injury patients treated with continuous renal replacement therapy

Figures & data

Table 1. Baseline characteristics of the study population.

Characteristics	Total (n = 149)	Survivors (n = 65)	Non-survivors (n = 84)	p Value
Age (years)	62.5 ± 13.7	60.9 ± 13.5	63.9 ± 14.0	0.17
Male, n (%)	95 (63.8)	39 (60.0)	56 (66.7)	0.40
Surgical admission, n (%)	19 (12.2)	6 (9.2)	13 (24.2)	0.19
Sepsis, n (%)	119 (79.9)	54 (83.1)	65 (77.4)	0.39
Oliguria, n (%)	132 (88.6)	55 (84.6)	77 (91.7)	0.18
Ventilator n (%)	108 (72.5)	36 (55.4)	72 (85.7)	0.01
No. of vasoactive drug	1.5 ± 1.1	1.2 ± 1.0	1.7 ± 1.1	0.01
No. of organ failure	2.4 ± 0.7	2.3 ± 0.7	2.6 ± 0.7	0.02
APACHE II score	27.9 ± 7.0	25.9 ± 6.9	29.5 ± 6.6	0.01
Systolic BP (mmHg)	105.1 ± 17.7	109.5 ± 18.6	101.6 ± 16.2	0.01
Diastolic BP (mmHg)	67.7 ± 13.0	70.3 ± 13.1	65.7 ± 12.6	0.03
Troponin-I (ng/mL)	1.2 ± 2.1	1.6 ± 6.4	0.9 ± 1.7	0.13
Leukocyte (10^3/μL)	14.8 ± 85.8	14.2 ± 85.7	15.2 ± 86.1	0.46
Hemoglobin (g/dL)	10.5 ± 2.4	10.4 ± 2.3	10.5 ± 2.4	0.69
Platelet (10^3/μL)	194.8 ± 83.2	130.8 ± 84.0	244.3 ± 114.3	0.41
BUN (mg/dL)	61.5 ± 29.7	58.7 ± 23.8	63.5 ± 33.4	0.33
Serum creatinine (mg/dL)	4.1 ± 4.3	3.7 ± 1.8	4.3 ± 5.5	0.43
eGFR (mL/min/1.73m^2)	22.1 ± 1.1	20.3 ± 11.5	23.5 ± 13.8	0.14
FDP (μg/dL)	52.7 ± 39.3	53.0 ± 34.3	52.4 ± 42.7	0.92
Fibrinogen (mg/dL)	328.4 ± 167.2	329.9 ± 153.7	327.2 ± 176.9	0.92
Prothrombin time (sec)	25.4 ± 60.0	19.6 ± 11.4	29.8 ± 78.9	0.30
BNP (pg/mL)	1645.9 ± 340.8	796.1 ± 897.6	2311.3 ± 434.6	0.01
Procalcitonin (ng/mL)	40.4 ± 59.4	24.7 ± 36.2	52.1 ± 40.2	0.01
pH	7.31 ± 0.14	7.33 ± 0.14	7.30 ± 0.15	0.24
RIFLE score (%)				0.45
Risk	15 (10%)	5 (8%)	10 (12%)
Injury	30 (20%)	16 (25%)	14 (17%)
Failure	104 (70%)	44 (67%)	60 (71%)

p-Value survivors versus non-survivors.

Values are expressed as mean ± S.D.

No, number; APACHE, acute physiological and chronic evaluation; BP, blood pressure; BUN, blood urea nitrogen; eGFR, estimated glomerular filtration rate; FDP, fibrinogen degradation products; BNP, brain natriuretic peptide; RIFLE score, risk, injury, failure, loss, and end-stage kidney failure.

Figure 1. Concentration of BNP as a marker of survival and death during CRRT.

Figure 2. Receiver operating characteristic curve for BNP at the start of CRRT. Area under the ROC curve was 0.77 and sensitivity and specificity were 71.2% and 74.8%, respectively.

Table 2. Baseline characteristics of study treatments and use of CRRT.

Characteristics	Total (n = 149)	Survivors (n = 65)	Non-survivors (n = 84)	p Value
Times to start CRRT (Hours)	31.3 ± 64.4	26.5 ± 73.5	35.1 ± 56.5	0.40
Duration of CRRT (Hours)	90.2 ± 69.5	90.4 ± 52.4	90.1 ± 80.6	0.90
Blood flow rate (mL/min)	140.5 ± 160.8	150.8 ± 171.4	132.5 ± 152.6	0.49
Dialysate flow rate (mL/min)	1288.9 ± 1164.7	1303.8 ± 282.3	1277.4 ± 988.9	0.83
Replacement flow rate (mL/min)	1279.3 ± 758.2	1326.2 ± 281.7	1275 ± 989.1	0.68
Flow rate of effluent (mL/kg/hr), prescribed	38.3 ± 7.4	39.4 ± 6.27	37.6 ± 8.20	0.13
Flow rate of effluent (mL/kg/hr), delivered	32.4 ± 6.3	33.1 ± 6.20	31.9 ± 6.3	0.30
Net ultrafiltration (mL/hr)	43.0 ± 33.5	42.6 ± 28.8	43.2 ± 36.9	0.74

p-Value survivors versus non-survivors.

Values are expressed as mean ± S.D.

CRRT, continuous renal replacement therapy.

Table 3. Patients’ characteristics stratifies according to BNP level upon starting CRRT.

Characteristics	Below 1054 pg/mL group (n = 72)	Above 1054 pg/mL group (n = 77)	p Value
Age (years)	59.7 ± 15.0	65.2 ± 12.1	0.02
Sepsis, n (%)	60 (83.3)	59 (76.6)	0.31
Oliguria, n (%)	60 (83.3)	72 (93.5)	0.05
Ventilator, n (%)	45 (62.5)	63 (81.8)	0.01
No. of vasoactive drug	1.3 ± 1.0	1.7 ± 1.1	0.02
No. of organ failure	2.3 ± 0.8	2.6 ± 0.6	0.02
APACHE II score	26.9 ± 7.0	28.8 ± 6.8	0.08
Systolic BP (mmHg)	107.8 ± 17.6	102.5 ± 17.5	0.07
Diastolic BP (mmHg)	70.7 ± 12.8	64.9 ± 12.6	0.01
Leukocyte (10^3/μL)	14.4 ± 79.6	15.1 ± 91.5	0.60
Hemoglobin (g/dL)	10.6 ± 2.4	10.4 ± 2.3	0.60
Platelet (10^3/μL)	134.9 ± 92.3	250.8 ± 116.1	0.40
BUN (mg/dL)	59.3 ± 28.0	63.3 ± 31.1	0.41
Serum creatinine (mg/dL)	3.6 ± 1.9	4.6 ± 5.9	0.17
eGFR	23.1 ± 14.7	21.1 ± 11.0	0.33
FDP (μg/dL)	50.2 ± 31.4	54.9 ± 45.3	0.46
Fibrinogen (mg/dL)	339.9 ± 189.7	317.5 ± 142.1	0.41
Prothrombin time (sec)	28.6 ± 84.9	22.3 ± 14.4	0.52
BNP (pg/mL)	395.6 ± 297.8	2356.0 ± 1028.4	0.01
Procalcitonin (ng/mL)	34.3 ± 51.7	45.6 ± 65.5	0.25
pH	7.31 ± 0.10	7.33 ± 0.15	0.32
Mortality, n (%)	25 (34.7)	59 (76.6)	0.01
Times to start CRRT (Hours)	33.5 ± 75.7	29.3 ± 52.1	0.69
Duration of CRRT (Hours)	83.2 ± 55.5	96.8 ± 80.2	0.24
Blood flow rate (mL/min)	143.1 ± 163.6	115.2 ± 22.4	0.06
Dialysate flow rate (mL/min)	1286.8 ± 285.6	1290.8 ± 1597.0	0.97
Replacement flow rate (mL/min)	1306.9 ± 251.4	1288.3 ± 1029.9	0.88
Flow rate of effluent (mL/kg/hr), prescribed	38.8 ± 6.7	37.9 ± 8.1	0.51
Flow rate of effluent (mL/kg/hr), delivered	32.2 ± 6.1	32.7 ± 6.5	0.67
Net ultrafiltration (mL/hr)	37.6 ± 28.6	47.9 ± 37.0	0.60

Values are expressed as mean ± S.D.

BNP, brain natriuretic peptide; CRRT, continuous renal replacement therapy; No, number; APACHE, acute physiological and chronic evaluation; BP, blood pressure; BUN, blood urea nitrogen; FDP, fibrinogen degradation products.

Table 4. Multivariable logistic regression analysis for the prediction of mortality in patients during CRRT.

Characteristics	B	Wald	OR (95% CI)	p Value
Ventilator care	0.672	1.401	1.959 (0.644–5.963)	0.236
No. of vasoactive drug	−0.015	0.004	0.985 (0.604–1.608)	0.953
No. of organ failure	0.148	0.153	1.159 (0.554–2.427)	0.695
APACHE II score	0.005	1.809	1.005 (0.932–1.084)	0.894
Systolic BP (mmHg)	−0.027	0.179	0.974 (0.936–1.012)	0.179
Diastolic BP (mmHg)	0.018	0.589	1.018 (0.973–1.066)	0.443
BNP (pg/mL)	0.001	12.083	1.001 (1.000–1.001)	0.001
Procalcitonin (ng/mL)	0.005	2.924	1.008 (0.999–1.018)	0.087

No, number; APACHE, acute physiological and chronic evaluation; BP, blood pressure; FDP, fibrinogen degradation products; BNP, brain natriuretic peptide.