Baseline hyponatremia does not predict two-year mortality in patients with chronic peritoneal dialysis

Figures & data

Figure 1. Distribution of observed serum sodium levels at baseline (n = 318).

Table 1. Baseline demographic and biochemical data in patients with CPD according to quartile of baseline serum Na levels.

Characteristics	Quartile 1 (124–135) (n = 84)	Quartile 2 (136–139) (n = 93)	Quartile 3 (140–141) (n = 65)	Quartile 4 (142–148) (n = 76)	p
Demographics
Age (years)	52.8 ± 11.40	49.0 ± 11.2	47.8 ± 11.3	44.0 ± 13.5	< 0.001
Female sex	45 (53.6)	65 (69.9)	42 (64.6)	47 (61.8)	0.160
Body mass index (kg/m^2)	22.4 ± 3.8	22.3 ± 3.4	22.9 ± 3.4	22.3 ± 3.4	0.752
Use of diuretics (yes)	24 (28.6)	18 (19.4)	19 (29.2)	21 (27.6)	0.409
Comorbidity
Co-morbidity index	0.45 ± 0.65	0.33 ± 0.56	0.15 ± 0.44	0.20 ± 0.40	0.002
DM (Yes)	21 (25.0)	16 (17.2)	5 (7.7)	3 (3.9)	0.001
Dialysis related data
PD duration (days)	1632.4 ± 1072.9	1604.1 ± 1092.6	1364.5 ± 936.7	1070.5 ± 859.3	0.001
Cr D/P, 4th hour	0.69 ± 0.13	0.68 ± 0.10	0.65 ± 0.09	0.64 ± 0.10	0.014
High and high average   Cr D/P, 4th hour (Yes)	49 (58.3)	55 (59.1)	27 (41.5)	31 (40.8)	0.021
Total Kt/V	2.18 ± 0.35	2.17 ± 0.34	2.14 ± 0.34	2.16 ± 0.40	0.914
Renal Kt/V	0.11 ± 0.17	0.10 ± 0.20	0.18 ± 0.31	0.25 ± 0.29	< 0.001
Standard total Ccr   (l/week/1.73 m^2)	56.9 ± 11.3	54.8 ± 11.6	54.8 ± 14.2	55.5 ± 13.1	0.671
nPNA (g/kg/day)	1.06 ± 0.25	1.05 ± 0.28	1.03 ± 0.22	1.00 ± 0.23	0.503
% of oligoanuria (<100 cc)	53 (63.1)	58 (62.3)	31 (47.7)	31 (40.8)	0.008
% of CAPD	77 (91.6)	82 (88.2)	56 (86.1)	60 (78.9)	0.119
Biochemical data
White blood cell counts (1000/μl)	7.2 ± 3.0	7.6 ± 2.7	8.4 ± 5.2	6.8 ± 2.1	0.04
Hemoglobin (g/dl)	9.7 ± 1.5	9.5 ± 1.8	9.4 ± 1.7	9.6 ± 1.6	0.567
Albumin (g/dl)	3.7 ± 0.5	3.9 ± 0.4	4.0 ± 0.5	4.0 ± 0.4	< 0.001
Creatinine (mg/dl)	10.9 ± 2.8	11.4 ± 2.4	12.5 ± 3.1	12.0 ± 2.9	0.004
Fasting sugar (mg/dl)	136.2 ± 83.8	116.0 ± 48.1	110.0 ± 35.0	104.9 ± 20.8	0.001
HbA1c (mg/dl)	6.0 ± 1.5	5.7 ± 1.1	5.6 ± 0.9	5.3 ± 1.0	0.002
Potassium (mg/dl)	3.8 ± 0.8	3.9 ± 0.7	4.0 ± 0.7	3.8 ± 0.6	0.411
Ferritin (μg/l)	261.0 (32–2630)	267.0 (7.0–2037)	261.0 (6.0–1489)	241.0 (12.0–1580)	0.381
Corrected-calcium (mg/dl)	10.4 ± 0.9	10.3 ± 1.05	10.3 ± 0.9	10.1 ± 0.8	0.149
Phosphate (mg/dl)	4.7 ± 1.6	4.8 ± 1.4	5.2 ± 1.2	4.9 ± 1.4	0.291
Intact parathyroid hormone (pg/ml)	89.5 (5.6–2162)	210.5 (5.5–1108)	172.0 (5.0–1143)	161.0 (10.1–1243)	0.985
Cardiovascular risks
Total cholesterol (mg/dl)	211.7 ± 53.7	221.3 ± 50.5	220.0 ± 53.2	211.3 ± 42.2	0.428
Triglyceride (mg/dl)	216.6 ± 162.1	226.9 ± 170.5	224.6 ± 155.5	204.8 ± 144.0	0.818
Cardiothoracic ratio	0.50 ± 0.07	0.50 ± 0.06	0.49 ± 0.07	0.47 ± 0.06	0.05

Note: p < 0.05 significant trends among four quartile groups. Non-normal distribution data were presented as median (minimum, maximum).

HbA1c: glcosylated hemoglobin; nPNA: normalized protein nitrogen appearance.

Table 2. Simple and multiple linear regression analysis of risk factors associated with baseline Na level in patients with CPD.

	Simple linear regression			Multiple linear regression
	β	95% C.I	p	β	95% C.I	p
Age (year)	−0.306	−0.139 to −0.068	<0.001	−0.230	−0.115 to −0.041	< 0.001
PD duration (days)	−0.182	−0.001 to 0	0.001	−0.134	0 to 0	0.021
Co-morbidity index	−0.178	−2.197 to −0.528	0.001
CT ratio	−0.184	−18.27 to −4.713	0.001
Sugar	−0.217	−0.025 to −0.008	<0.001
Cr	0.184	0.110 to 0.428	0.001
Albumin	0.286	1.583 to 3.450	<0.001	0.143	0.283 to 2.237	0.012
D/P Cr	−0.153	−9.739 to −1.623	0.006
Renal Kt/V	0.181	1.184 to 4.751	0.001	0.145	0.507 to 4.234	0.013

Table 3. Univariate and multivariate Cox analysis of all-cause two-year mortality in patients with CPD, according to basal variables and serum sodium level.

	Univariate Cox regression		Multivariate Cox regression
	Hazard ratio (95% CI)	p	Hazard ratio (95% CI)	p
Age (year)	1.043 (1.013–1.074)	0.004	1.035 (1.005–1.065)	0.02
Co-morbidity index	3.219 (2.003–5.713)	<0.001	2.580 (1.609–4.138)	<0.001
CT ratio	2.596E3 (15.5–4.349E5)	0.003
HbA1c	1.396 (1.157–1.684)	<0.001
Cr	0.863 (0.750–0.991)	0.038
Na	0.910 (0.842–0.983)	0.016
Albumin	0.333 (0.200–0.553)	<0.001	0.329 (0.167–0.646)	0.001
D/P Cr	20.045 (0.999–402.173)	0.05