Paradoxical Association Between Intradialytic Blood Pressure Change and Long-Term Mortality with Different Levels of Interdialytic Weight Gain

Figures & data

Figure 1 Flowchart of the study.

Table 1 Demographic, Clinical and Biochemical Data of the Patients

Characteristics	IDWG % <3.3%	IDWG% 3.3%–4.6%	IDWG % ≥4.6%
	T1 (n=68)	T2 (n=68)	T3 (n=68)
Demographic data
Age (year)	59.57±15.96	57.48±12.92	49.20±13.97^**, b
Male (n,%)	21,35%	41,40.6%	21,48.8%
Normalized ultrafiltration rate (mL/h/kg)	5.40±2.79	11.02±1.88^d	14.07±3.21^**, b
IDWG (kg)	1.10±0.61	2.48±0.56^d	3.17±0.76^**, b
Preserved residual kidney function (%)	22(36.7%)	9(8.9%) ^d	2(4.7%)**
Duration of dialysis (months)	23.00(12.50,63.75)	45.00(24.50,74.50) ^c	46.00(22.25,79.25) *
spKt/Vurea	1.44(1.29,1.70)	1.40(1.25,1.76)	1.42(1.20,1.75)
BMI (kg/m^2)	24.47±8.05	23.72±9.60	19.93±8.35^*, a
Dry weight (kg)	62.98±11.09	61.76±11.93	56.29±12.40^**, a
Biochemical parameters
Serum albumin (g/L)	40.25±3.05	38.61±3.61^d	39.98±3.73^a
Serum prealbumin (g/L)	0.35±0.06	0.33±0.09	0.36±0.10
Serum creatinine (μmol/L)	941.21±265.31	1063.35±272.98^c	1052.95±294.51
Hemoglobin (g/L)	107.65±13.00	104.35±15.90	104.59±15.91
Cardiac condition
NT-proBNP (pg/mL)	1302(773,4098)	3602(2186,5917) ^d	5057(2363,16,369) **, ^a
EF (%)	66.68±7.09	67.00±5.60	65.89±8.39
LVMI (g/m^2.7)	46.14±16.85	53.03±21.47	45.60±12.67
Antihypertensive medication
Antihypertensive medication (types)	2.15±1.21	1.79±1.13	2.26±1.26
Antihypertensive medication dosage (tablets)	2.85±2.05	2.23±1.58	3.19±2.24^a
Predialysis BP
Predialysis SBP (mmHg)	135.24±13.34	135.62±18.46	137.48±16.14
Predialysis DBP (mmHg)	81.94±8.94	81.73±11.31	84.53±9.10
Predialysis MAP (mmHg)	99.39±9.25	99.91±13.29	102.54±11.34
Predialysis PP (mmHg)	53.80±9.80	53.52±11.21	54.02±13.71
Comorbidities
Hypertension (%)	50(83.3%)	82(81.2%)	37(86.0%)
Cardiovascular disease (%)	2(3.3%)	6(5.9%)	4(9.3%)
Cerebrovascular disease (%)	1(1.7%)	2(2.0%)	1(2.3%)

Notes: Continuous variables given as mean ± standard deviation or median (25th; 75th percentile); categorical variables given as number (percentage). *P<0.05, **P<0.01: T1 vs T3; ^aP<0.05, ^bP<0.01: T2 vs T3; ^cP<0.05, ^dP<0.01: T1 vs T2.

Abbreviations: BMI, body mass index; IDWG, interdialytic weight gain; NT-proBNP, N-terminal pro-B-type natriuretic peptide; EF, ejection fraction; LVMI, left ventricular mass index; SBP, systolic blood pressure; DBP, diastolic blood pressure; MAP, mean arterial pressure; PP, pulse pressure; Preserved residual kidney function: 24h urine output over 100mL.

Figure 2 Association of intradialytic blood pressure change and IDWG %.

Figure 3 (A) Accumulative overall survival rate of different intradialytic blood pressure change in low IDWG% group. (B) Accumulative overall survival rate of different intradialytic blood pressure change in median IDWG% group. (C) Accumulative overall survival rate of different intradialytic blood pressure change in high IDWG% group.

Table 2 Cox Regression Analysis of Intradialytic Blood Pressure Changes on Mortality of Different IDWG% Tertiles

			HR	P
Crude model 1	low IDWG% group	SBP variation > 20mmHg vs ≤ 20mmHg	2.51 (1.02~6.19)	0.045
		DBP variation > 10mmHg vs ≤ 10mmHg	2.59 (1.02~6.57)	0.046
		MAP variation > 15mmHg vs ≤ 15mmHg	1.80 (1.08~3.01)	0.024
		PP variation > 10mmHg vs ≤10mmHg	1.81 (1.14~2.89)	0.013
	median IDWG% group	SBP variation > 20mmHg vs ≤ 20mmHg	1.71 (0.83~3.49)	0.143
		DBP variation > 10mmHg vs ≤ 10mmHg	1.41 (0.69~2.88)	0.350
		MAP variation > 15mmHg vs ≤ 15mmHg	3.73 (0.89~15.61)	0.072
		PP variation > 10mmHg vs ≤10mmHg	2.34 (1.14~4.80)	0.020
	high IDWG% group	SBP variation > 20mmHg vs ≤ 20mmHg	0.25 (0.08~0.79)	0.018
		DBP variation > 10mmHg vs ≤ 10mmHg	0.23 (0.07~0.77)	0.017
		MAP variation > 15mmHg vs ≤ 15mmHg	0.26 (0.08~0.86)	0.028
		PP variation > 10mmHg vs ≤10mmHg	0.29 (0.09~0.91)	0.034
Adjusted model 2*	low IDWG% group	SBP variation > 20mmHg vs ≤ 20mmHg	2.80 (1.08~7.23)	0.033
		DBP variation > 10mmHg vs ≤ 10mmHg	3.00 (1.11~8.06)	0.030
		MAP variation > 15mmHg vs ≤ 15mmHg	3.09 (1.09~8.75)	0.034
		PP variation > 10mmHg vs ≤10mmHg	3.53 (1.18~10.54)	0.024
	median IDWG% group	SBP variation > 20mmHg vs ≤ 20mmHg	1.47 (0.51~4.24)	0.472
		DBP variation > 10mmHg vs ≤ 10mmHg	1.78 (0.68~4.67)	0.240
		MAP variation > 15mmHg vs ≤ 15mmHg	4.62(0.59~36.48)	0.147
		PP variation > 10mmHg vs ≤10mmHg	1.94 (0.68~5.48)	0.214
	high IDWG% group	SBP variation > 20mmHg vs ≤ 20mmHg	0.25 (0.08~0.82)	0.022
		DBP variation > 10mmHg vs ≤ 10mmHg	0.21 (0.04~0.98)	0.046
		MAP variation > 15mmHg vs ≤ 15mmHg	0.25 (0.06~1.02)	0.054
		PP variation > 10mmHg vs ≤10mmHg	0.25 (0.08~0.80)	0.020

Notes: model 2: adjusted for age, gender, body mass index, dialysis vintage, preserved residual kidney function, predialysis blood pressure (systolic blood pressure; diastolic blood pressure; mean arterial pressure; pulse pressure).

Abbreviations: IDWG, interdialytic weight gain; SBP, systolic blood pressure; DBP, diastolic blood pressure; MAP, mean arterial pressure; PP, pulse pressure.