Evaluation of volume overload by bioelectrical impedance analysis, NT-proBNP and inferior vena cava diameter in patients with stage 3&4 and 5 chronic kidney disease

Figures & data

Table 1. The distribution of underlying renal diseases in both study groups.

	CKD Stage 3&4 (n = 62)		CKD Stage 5 (n = 68)
Etiology	Patients (n)	Percentage (%)	Patients (n)	Percentage (%)
Hypertension	28	45%	26	39%
Diabetes mellitus	22	35%	23	34%
Glomerulonephritis	6	10%	7	10%
Idiopathic	6	10%	4	6%
Policystic kidney disease	–	–	1	1%
Obstructive nephropathy	–	–	7	10%

Figure 1. The box plots shows (a) the IVC index, (b) log NT-proBNP and (c) OH/ECW values in patients with CKD stage 3&4 and 5.

Table 2. Demographic, clinical, laboratory and BIA characteristics of the groups.

Parameters	CKD Stage 3&4 (n = 62)	CKD Stage 5 (n = 68)	p
Age (years)	54.14 ± 13.52	51.05 ± 13.64	1.112
Gender (M/F)	33/29	32/36	0.482
GFR (ml/min/1.73 m^2)	28.93 ± 5.30	8.83 ± 1.33	<0.001
SBP (mmHg)	125.32 ± 15.01	133.75 ± 20.13	0.008
DBP (mmHg)	78.95 ± 8.05	83.89 ± 10.71	0.003
Urea (mg/dL)	98.58 ± 20.23	171.73 ± 41.80	<0.001
Creatinine (mg/dL)	2.89 ± 0.80	6.80 ± 1.32	<0.001
Na (mEq/L)	136.88 ± 4.21	136.89 ± 3.84	0.989
Albumin (g/dL)	3.03 ± 0.70	2.80 ± 0.80	0.090
Proteinuria (gr/day)	2.01 ± 0.29	2.96 ± 0.52	0.020
Residual urine (l/day)	2.55 ± 0.66	1.56 ± 0.49	<0.001
OH(l)	2.26 ± 0.47	3.91 ± 0.83	0.001
TBW(l)	36.53 ± 6.99	37.70 ± 7.76	0.369
ECW(l)	17.70 ± 3.84	19.67 ± 4.61	0.010
ICW(l)	18.79 ± 3.85	18.02 ± 4.16	0.276
ECW/TBW	0.46 ± 0.04	0.51 ± 0.05	<0.001
ECW/ICW	0.94 ± 0.18	1.09 ± 0.25	<0.001
OH/ECW	0.12 ± 0.03	0.18 ± 0.05	<0.001
IVC index (mm/m^2)	8.06 ± 1.50	11.2 ± 2.12	<0.001
Log NT-proBNP (pg/mlt)	2.08 ± 0.40	2.51 ± 0.43	<0.001

Note: GFR: glomerular filtration rate; SBP: systolic blood pressure; DBP: diastolic blood pressure; OH: overhydration; TBW: total body water; ECW: extracellular water; ICW: intracellular water; IVC index: inferior vena cava index; Log: logarithm.

Statistically significant results (p < 0.05) are shown in bold.

Figure 2. (a) Comparison of systolic blood pressure (SBP) between overhydrated CKD patients and non-overhydrated CKD patients; (b) comparison of diastolic blood pressure (DBP) between overhydrated CKD patients and non-overhydrated CKD patients.

Figure 3. (a) Comparison of IVC index between overhydrated CKD patients and non-overhydrated CKD patients; (b) comparison of log NT-proBNP between overhydrated CKD patients and non-overhydrated CKD patients.

Table 3. Evaluation of the overhydration between the groups.

	OH/ECW > 0.15	OH/ECW ≤ 0.15	Total
CKD Stage 3&4	18	44	62
	29.0%	71.0%	100.0%
CKD Stage 5	41	27	68
	60.3%	39.7%	100.0%
Total	59	71	130
	45.4%	54.6%	100.0%

Note: CKD Stage 3&4 versus CKD Stage 5, p < 0.001.

Table 4. Correlations between OH/ECW and study parameters.

Variable	r	p
Age	−0.053	0.548
Log NT-proBNP	0.605	<0.001
Albumin	−0.461	<0.001
Proteinuria	0.391	<0.001
Residual urine	−0.369	<0.001
GFR	−0.346	<0.001
SBP	0.403	<0.001
DBP	0.342	<0.001
Urea	0.320	<0.001
Creatinine	0.323	<0.001
Na	0.074	0.405
OH	0.940	<0.001
ECW	0.546	<0.001
ICW	−0.194	0.147
TBW	0.214	0.015
ECW/TBW	0.798	<0.001
ECW/ICW	0.799	<0.001
IVC index	0.497	<0.001

Note: Abbreviations: as in Table 2.

Statistically significant results (p < 0.05) are shown in bold.

Table 5. Covariables associated with OH/ECW by multiple linear regression.

Independent variables	Beta coefficient	95% CI B coefficient	Standardized Beta coefficient	p
Sex (0 = female, 1 = male)	3.523	1.082 to 5.965	0.147	0.005
Residual urine	−0.013	−1.701 to 1.675	−0.001	0.988
Albumin	−2.325	−4.098 to −0.552	−0.147	0.011
Proteinuria	0.171	−0.389 to 0.730	0.033	0.547
GFR	−0.049	−0.163 to 0.065	−0.053	0.397
ECW/TBW	70.369	19.302 to 121.435	0.316	0.007
ECW/ICW	23.290	12.175 to 34.404	0.455	<0.001
TBW	0.073	−0.093 to 0.239	0.045	0.385
Constant	−38.891

Notes: CI: Confidence interval. Model: p < 0.001; R²= 0.727. Abbreviations: as in Table 2.

Statistically significant results (p < 0.05) are shown in bold.