Potassium supplementation and long-term outcomes in chronic peritoneal dialysis patients with end-stage renal disease: a propensity score matching study

Figures & data

Figure 1. Enrollment scheme and study flow.

Table 1. Baseline characteristics of potassium supplementation and no potassium supplementation, before and after propensity score matching^a.

	Before matching			After matching
Variables	Potassium supplementation (N = 507)	NO potassium supplementation (N = 667)	p-Values	Potassium supplementation (N = 338)	NO potassium supplementation (N = 338)	p-Values
Age (yrs)	55.3 ± 12.6	52.3 ± 10.5	0.027	54.1 ± 11.9	53.3 ± 10.7	0.26
Male no. (%)	213 (59.7)	331 (48.9)	0.0001	208 (58.3)	189 (53.8)	0.14
Etiology of ESRD no. (%)
Nephritis	224 (62.7)	456 (67.4)	0.14	218 (64.4)	217 (64.2)	0.75
Hypertensive nephrosclerosis	17 (4.8)	54 (8.0)	0.05	16 (4.7)	19 (5.6)	0.60
Diabetic nephrology	65 (18.2)	106 (15.7)	0.29	57 (16.9)	61 (18.0)	0.68
Polycystic kidney disease	16 (4.5)	42 (6.2)	0.25	16 (4.7)	18 (5.3)	0.72
Other	35 (9.8)	19 (2.7)	p < 0.0001	31 (9.3)	23 (6.9)	0.26
History of cardio-cerebrovascular disease
Congestive heart failure	86 (24.1)	157 (23.2)	0.47	58 (17.2)	61 (18.0)	0.76
Ischemic heart disease	16 (4.5)	41 (6.1)	0.29	15 (4.4)	17 (5.0)	0.72
Cerebrovascular disease	31 (8.7)	63 (9.3)	0.74	26 (7.7)	25 (7.4)	0.88
Peripheral artery disease	27 (7.6)	61 (9.0)	0.43	25 (7.4)	25 (7.4)	1.0
Duration of dialysis (month)	47.3 ± 18.7	51.1 ± 17.9	0.29	51.2 ± 16.8	52.6 ± 18.4	0.73
Body mass index (kg/m^2)	69.2 ± 10.8	68.5 ± 9.5	0.13	67.6 ± 11.2	68.1 ± 10.7	0.54
Diabetes mellitus	62 (17.4)	71 (10.5)	0.0017	58 (21.6)	65 (21.6)	1.0
ACEIs/ARBs	271 (75.9)	512 (75.6)	0.92	258 (76.3)	263 (77.8)	0.65
Smoking (%)	52 (14.6)	119 (17.6)	0.21	46 (13.6)	50 (14.8)	0.66
Urine volume			0.49			0.81
<500 (mL/24h)	137 (38.4)	245 (36.2)		135 (40.0)	138 (40.8)
≥500 (mL/24 h)	220 (61.6)	432 (63.8)		203 (60.0)	200 (59.2)
Total Kt/vurea	1.54 ± 0.46	1.61 ± 0.59	0.086	1.58 ± 0.46	1.60 ± 0.59	0.37
Mean plasma potassium (mmol/L)	3.22 ± 0.43	3.36 ± 0.54	0.003	3.16 ± 0.44	3.16 ± 0.58	0.62
Mean plasma Hs-CRP (mg/L)	8.83 ± 3.27	7.82 ± 2.48	0.04	8.38 ± 3.32	8.42 ± 2.69	0.69
Mean plasma albumin (g/L)	35.2 ± 5.8	35.0 ± 4.1	0.19	35.1 ± 4.9	34.9 ± 3.7	0.84
Mean plasma prealbumin (mg/L)	335.7 ± 82.3	342.2 ± 52.9	0.13	334.8 ± 78.2	337.5 ± 51.5	0.50
Mean hemoglobin (g/L)	12.2 ± 2.4	12.6 ± 2.6	0.29	12.4 ± 2.3	12.4 ± 2.5	0.59
Charlson comorbidity index	5.3 ± 1.7	5.7 ± 1.1	0.03	5.5 ± 1.2	5.5 ± 1.3	0.94

Note: ^aThe effectiveness of bias reduction after matching was assessed by paired t-test for continuous variables and McNemar’s test for categorical variables.

ESRD: End stage renal disease; ACEIs: angiotensin converting enzyme inhibitor; ARBs: angiotensin receptor blockers; Hs-CRP: high-sensitivity C-reactive protein.

Figure 2. The Kaplan–Meier plots for all-cause mortality and cardiovascular mortality by the use of oral potassium supplementation.

Figure 3. All-cause mortality, according to subgroup.

Table 2. The relationship between hypokalemia correction and all-cause and cardiovascular mortality.

Corrected levels of serum potassium (mEq/L)
	<3.0	3.0 to <4.0	4.0 to <5.0	>5.0
No. of patients	47	335	263	31
All-cause mortality
No. of deaths	22	120	67	13
Unadjusted HR (95% CI)	2.57 (1.36–4.87)	1.63 (1.14–2.33)	1.0 (Reference)	2.11 (0.98–4.54)
Adjusted HR (95% CI)^a	2.23 (1.17–3.72)	1.35 (0.89–1.81)	1.0 (Reference)	1.74 (1.05–3.72)
Cardiovascular mortality
No. of deaths	20	108	58	12
Unadjusted HR (95% CI)	2.62 (1.37–5.00)	1.68 (1.16–2.44)	1.0 (Reference)	2.23 (1.02–4.87)
Adjusted HR (95% CI)^a	2.18 (1.18–4.31)	1.45 (0.92–1.99)	1.0 (Reference)	1.89 (1.11–3.95)

^aAdjusted for age, sex, BMI, etiology of ESRD, diabetic status, duration of dialysis, total Kt/v urea and Charlson comorbidity index.

HR: hazard ratio; CI: Charlson comorbidity index; BMI: Body Mass Index.