Association between the prognostic nutritional index (PNI) and all-cause mortality in patients with chronic kidney disease

Figures & data

Table 1. Baseline characteristics of participants who were Still alive vs. those who were deceased by December 31, 2015.

Variable	Still alive, N = 1495	Deceased, N = 649	P value
Age (years)	70.61 (10.13)	76.76 (7.38)	<0.001*
Body mass index (kg/m^2)	29.87 (6.43)	28.61 (6.48)	<0.001*
Waist circumference (cm)	103.71 (14.56)	102.57(15.60)	0.127
WBC (×10 ^9/L)	6.90 (5.80–8.20)	7.20 (5.90–8.80)	0.006*
Absolute lymphocyte count (×10 ^9/L)	1.90 (1.50–2.40)	1.60 (1.20–2.20)	<0.001*
Hemoglobin concentration (mg/dL)	13.52 (1.59)	13.13 (1.64)	<0.001*
Hematocrit (%)	39.83 (4.58)	38.81 (4.95)	<0.001*
Platelet count (×10 ^9/L)	235.29 (69.20)	232.86 (79.96)	0.477
Total protein (g/L)	70.66 (4.97)	70.51 (5.77)	0.540
Albumin (g/L)	41.46 (3.07)	40.31 (3.98)	<0.001*
Alanine aminotransferase (U/L)	19.00 (15.00–24.00)	17.00 (14.00–22.00)	<0.001*
Aspartate aminotransferase (U/L)	23.00 (20.00–27.00)	24.00 (20.00–28.00)	0.374
Alkaline phosphatase (IU/L)	70.71 (23.80)	77.59 (30.30)	<0.001*
Gamma glutamyl transferase (U/L)	19.00 (14.00–27.50)	21.00 (15.00–35.00)	<0.001*
Total bilirubin (μmol/L)	12.00 (4.56)	13.21 (5.07)	<0.001*
Blood urea nitrogen (mmol/L)	7.68 (3.15)	9.35 (4.27)	<0.001*
Creatinine (μmol/L)	122.76 (45.93)	135.57 (58.05)	<0.001*
Uric acid (μmol/L)	388.21 (91.83)	412.21 (105.78)	<0.001*
Glucose (mmol/L)	6.40 (2.70)	6.65 (2.75)	0.052
Triglycerides (mmol/L)	1.34 (0.98–1.95)	1.41 (1.07–2.00)	0.113
Cholesterol (mmol/L)	4.91 (1.11)	4.72 (1.17)	<0.001*
Potassium (mmol/L)	4.15 (0.45)	4.24 (0.47)	<0.001*
Sodium (mmol/L)	139.56 (2.54)	139.39 (3.02)	0.211
Chloride (mmol/L)	103.92 (3.32)	103.46 (4.08)	0.011*
Bicarbonate (mmol/L)	25.08 (2.49)	24.87 (2.94)	0.119
Total calcium (mmol/L)	2.37 (0.11)	2.35 (0.12)	<0.001*
Phosphorus (mmol/L)	1.23 (0.19)	1.24 (0.20)	0.484
Iron (μmol/L)	14.06 (5.24)	13.84 (5.62)	0.385
Lactate dehydrogenase (U/L)	139.69 (28.97)	150.31 (40.77)	<0.001*
C-reactive protein group [n (%)]			<0.001*
<0.50 mg/dL	595 (39.80%)	358 (55.16%)
0.50–1.00 mg/dL	112 (7.49%)	92 (14.18%)
>1.00 mg/dL	94 (6.29%)	87 (13.41%)
Missing	694 (46.42%)	112 (17.26%)
Osmolality (mmol/kg)	282.65 (5.85)	284.21 (7.59)	<0.001*
Prognostic nutritional index	51.82 (12.20)	50.08 (11.85)	0.002*
ACR (mg/g)	130.02 (68.02–421.41)	334.55 (119.20–984.77)	<0.001*
eGFR (mL/min/1.73 m²)	48.49 (10.03)	43.51 (11.89)	<0.001*
eGFR group [n (%)]			<0.001*
30–59 mL/min/1.73 m²	1401 (93.71%)	554 (85.36%)
15–29 mL/min/1.73 m²	80 (5.35%)	84 (12.94%)
< 15 mL/min/1.73 m²	14 (0.94%)	11 (1.69%)
Male [n (%)]	675 (45.15%)	345 (53.16%)	<0.001*
Race [n (%)]			<0.001*
Mexican American	114 (7.63%)	40 (6.16%)
Other Hispanic	93 (6.22%)	29 (4.47%)
Non-Hispanic White	908 (60.74%)	457 (70.42)
Non-Hispanic Black	306 (20.47%)	104 (16.02%)
Other, Including Multi-Racial	74 (4.95%)	19 (2.93%)
Smokers [n (%)]	723 (48.36%)	360 (55.47%)	0.020*
Drinkers [n (%)]	260 (17.39%)	130 (20.03%)	0.314
Education [n (%)]			<0.001*
Level 1	211 (14.12%)	137 (21.11%)
Level 2	239 (16.00%)	124 (19.11%)
Level 3	375 (25.10%)	155 (23.88%)
Level 4	376 (25.17%)	151 (24.27%)
Level 5	291 (19.48%)	79 (12.17%)
Marital status [n (%)]			<0.001*
Married	819 (54.82%)	290 (44.68%)
Widowed	354 (23.69%)	260 (40.06%)
Divorced	183 (12.25%)	62 (9.55%)
Separated	27 (1.81%)	13 (2.00%)
Never married	81 (5.42%)	19 (2.93%)
Living with partner	29 (1.94%)	4 (0.62%)
PIR [n (%)]			<0.001*
0–0.99	226 (15.12%)	101 (15.56%)
1.00–2.99	660 (44.15%)	351 (54.08%)
> =3.00	493 (32.98%)	131 (20.18%)
Missing	116 (7.76%)	66 (10.17%)
Diabetes [n (%)]	432 (28.90%)	209 (32.20%)	0.259
Hypertension [n (%)]	1106 (73.98%)	462 (71.19%)	0.232
Heart failure [n (%)]	148 (9.90%)	152 (23.42%)	<0.001*
Coronary heart disease [n (%)]	188 (12.58%)	128 (19.72%)	<0.001*
Angina [n (%)]	116 (7.76%)	77 (11.86%)	0.002*
Myocardial infarction [n (%)]	189 (12.64%)	142 (21.88%)	<0.001*
Stroke [n (%)]	158 (10.57%)	126 (19.41%)	<0.001*
Emphysema [n (%)]	45 (3.01%)	58 (8.94%)	<0.001*
Hepatopathy [n (%)]	31 (2.07%)	20 (3.08%)	0.246
Cancer [n (%)]	327 (21.87%)	172 (26.50%)	0.042*
Gout [n (%)]	161 (10.77%)	89 (13.71%)	<0.001*

Abbreviations: ACR, urinary albumin-to-creatinine ratio; eGFR, estimated glomerular filtration rate; PIR, ratio of family income to poverty; WBC, white blood cell count.

* P value < 0.05.

Table 2. Baseline characteristics of participants according to the PNI group.

Variable	Q1 (n = 500)	Q2 (n = 519)	Q3 (n = 515)	Q4 (n = 610)	P value
	PNI < 47.5	47.5 < = PNI < 50.5	50.5 < = PNI <53.5	PNI > = 53.5
Age (years)	74.43 (8.52)	72.56 (10.18)	72.49 (9.76)	70.77 (10.19)	<0.001*
Body mass index (kg/m^2)	29.83 (7.04)	29.42 (6.75)	29.55 (6.26)	29.25 (5.89)	0.813
Waist circumference (cm)	104.46 (15.81)	103.29 (15.05)	103.68 (15.11)	102.42 (13.71)	0.180
WBC (×10 ^9/L)	6.40 (5.40–7.90)	6.60 (5.60–7.80)	6.90 (6.00–8.00)	8.00 (6.90–9.30)	<0.001*
Absolute lymphocyte count (×10 ^9/L)	1.30 (1.00–1.60)	1.60 (1.30–1.90)	1.90 (1.60–2.20)	2.60 (2.10–3.00)	<0.001*
Hemoglobin concentration (mg/dL)	12.82 (1.66)	13.30 (1.64)	13.70 (1.49)	13.71 (1.53)	<0.001*
Hematocrit (%)	37.92 (4.89)	39.30 (4.74)	40.32 (4.40)	40.35 (4.45)	<0.001*
Platelet count (×10 ^9/L)	221.66 (72.53)	228.92 (70.13)	231.53 (64.54)	252.47 (77.80)	<0.001*
Total protein (g/L)	68.22 (5.48)	70.22 (5.01)	71.00 (4.70)	72.58 (4.75)	<0.001*
Albumin (g/L)	37.57 (3.22)	40.72 (2.17)	42.15 (2.25)	43.47 (2.70)	<0.001*
Alanine aminotransferase (U/L)	17.00 (14.00–21.00)	18.00 (15.00–23.00)	19.00 (15.00–23.00)	19.00 (16.00–24.00)	<0.001*
Aspartate aminotransferase (U/L)	22.00 (19.00–27.00)	24.00 (20.00–27.00)	24.00 (20.00–28.00)	24.00 (21.00–28.00)	<0.001*
Alkaline phosphatase (IU/L)	79.37 (33.70)	74.17 (25.86)	68.73 (21.02)	69.65 (21.63)	<0.001*
Gamma glutamyl transferase (U/L)	18.50 (14.00–28.25)	19.00 (14.00–29.00)	19.00 (14.00–27.00)	20.00 (15.00–30.00)	0.133
Total bilirubin (μmol/L)	12.20 (4.92)	12.66 (4.91)	12.79 (4.75)	11.89 (4.42)	0.005*
Blood urea nitrogen (mmol/L)	9.12 (4.19)	8.30 (3.98)	7.88 (3.18)	7.60 (2.88)	<0.001*
Creatinine (μmol/L)	122.88 (106.08–152.05)	114.92 (100.78–132.60)	114.92 (98.12–131.72)	114.04 (99.01–131.50)	<0.001*
Uric acid (μmol/L)	402.22 (102.12)	397.52 (100.11)	387.69 (90.08)	394.77 (94.92)	0.111
Glucose (mmol/L)	5.86 (5.11–7.40)	5.66 (5.00–6.99)	5.61 (5.05–6.83)	5.55 (5.00–6.49)	<0.001*
Triglycerides (mmol/L)	1.22 (0.89–1.79)	1.28 (0.96–1.85)	1.42 (1.12–2.06)	1.53 (1.15–2.20)	<0.001*
Cholesterol (mmol/L)	4.62 (1.13)	4.77 (1.04)	4.89 (1.08)	5.08 (1.20)	<0.001*
Potassium (mmol/L)	4.24 (0.46)	4.17 (0.46)	4.16 (0.43)	4.14 (0.46)	<0.001*
Sodium (mmol/L)	139.50 (2.89)	139.65 (2.55)	139.54 (2.64)	139.35 (2.69)	0.306
Chloride (mmol/L)	104.13 (4.07)	103.99 (3.45)	103.64 (3.33)	103.42 (3.39)	0.004*
Bicarbonate (mmol/L)	25.07 (3.08)	25.15 (2.63)	25.09 (2.40)	24.80 (2.40)	0.107
Total calcium (mmol/L)	2.30 (0.11)	2.36 (0.10)	2.38 (0.12)	2.41 (0.10)	<0.001*
Phosphorus (mmol/L)	1.24 (0.21)	1.23 (0.18)	1.22 (0.19)	1.26 (0.18)	0.006*
Iron (μmol/L)	12.62 (5.27)	13.61 (5.12)	15.11 (5.33)	14.50 (5.38)	<0.001*
Lactate dehydrogenase (U/L)	158.34 (34.37)	142.94 (31.45)	139.84 (30.30)	140.95 (35.87)	<0.001*
C-reactive protein group [n (%)]					<0.001*
<0.50 mg/dL	181 (36.20%)	233 (44.89%)	256 (49.71%)	283 (46.39%)
0.50–1.00 mg/dL	62 (12.40%)	50 (9.63%)	40 (7.77%)	52 (8.52%)
>1.00 mg/dL	80 (16.00%)	46 (8.86%)	25 (4.85%)	30 (4.92%)
Missing	177 (35.40%)	190 (36.61%)	194 (37.67%)	245 (40.16%)
Osmolality (mmol/kg)	284.59 (7.16)	283.53 (6.28)	282.67 (6.18)	281.95 (5.97)	<0.001*
ACR (mg/g)	283.96 (92.38–944.84)	193.92 (84.44–668.67)	144.30 (75.89–413.02)	134.33 (69.21–446.14)	<0.001*
eGFR (mL/min/1.73 m²)	43.70 (12.41)	47.44 (10.71)	47.56 (10.14)	48.79 (9.61)	<0.001*
eGFR group [n (%)]					<0.001*
30–59 mL/min/1.73 m²	431 (86.20%)	473 (91.14%)	477 (96.62%)	574 (94.10%)
15–29 mL/min/1.73 m²	52 (10.40%)	40 (7.71%)	38 (7.38%)	34 (5.57%)
< 15 mL/min/1.73 m²	17 (3.40%)	6 (1.16%)	0 (0.00%)	2 (0.33%)
Male [n (%)]	257 (51.40%)	257 (49.52%)	229 (44.47%)	277 (45.41%)	0.076
Race [n (%)]					0.013*
Mexican American	36 (7.20%)	40 (7.71%)	32 (6.21%)	46 (7.54%)
Other Hispanic	30 (6.00%)	26 (5.01%)	21 (4.08%)	45 (7.38%)
Non-Hispanic White	307 (61.40%)	321 (61.85%)	367 (71.26%)	370 (60.66%)
Non-Hispanic Black	106 (21.20%)	113 (21.77%)	70 (13.59%)	121 (19.84%)
Other, Including Multi-Racial	21 (4.20%)	19 (3.66%)	25 (4.85%)	28 (4.59%)
Smokers [n (%)]	267 (53.40%)	257 (49.52%)	268 (52.04%)	291 (47.70%)	0.291
Drinkers [n (%)]	100 (20.00%)	92 (17.73%)	75 (14.56%)	123 (20.16%)	0.208
Education [n (%)]					0.566
Level 1	94 (18.80%)	80 (15.44%)	75 (14.56%)	99 (16.23%)
Level 2	96 (19.20%)	88 (16.99%)	80 (15.53%)	99 (16.23%)
Level 3	107 (21.40%)	122 (23.55%)	147 (28.54%)	154 (25.25%)
Level 4	113 (22.60%)	134 (25.87%)	129 (25.05%)	151 (24.75%)
Level 5	88 (17.60%)	93 (17.95%)	82 (15.92%)	107 (17.54%)
Marital status [n (%)]					0.051
Married	241 (58.20%)	264 (50.97)	296 (57.48%)	308 (50.49%)
Widowed	170 (34.00%)	141 (27.22%)	133 (25.83%)	170 (27.87%)
Divorced	45 (9.00%)	65 (12.55%)	53 (10.29%)	82 (13.44%)
Separated	10 (2.00%)	9 (1.74%)	7 (1.36%)	14 (2.30%)
Never married	23 (4.60%)	29 (5.60%)	21 (4.08%)	27 (4.43%)
Living with partner	9 (1.80%)	10 (1.93%)	5 (0.97%)	9 (1.48%)
PIR [n (%)]					0.470
0–0.99	71 (14.20%)	74 (14.26%)	77 (14.95%)	105 (17.21%)
1.00–2.99	253 (50.60%)	241 (46.44%)	245 (47.57%)	272 (44.59%)
> =3.00	129 (25.80%)	157 (30.25%)	156 (30.29%)	182 (29.84%)
Missing	47 (9.40%)	47 (9.06%)	37 (7.18%)	51 (8.36%)
Diabetes [n (%)]	181 (36.20%)	150 (28.90%)	138 (26.80%)	172 (28.20%)	0.016*
Hypertension [n (%)]	371 (74.20%)	373 (71.87%)	387 (75.15%)	437 (71.64%)	0.390
Heart failure [n (%)]	101 (20.20%)	78 (15.03%)	63 (12.23%)	58 (9.51%)	<0.001*
Coronary heart disease [n (%)]	89 (17.89%)	80 (15.41%)	75 (14.56%)	72 (11.80%)	0.032*
Angina [n (%)]	50 (10.00%)	55 (10.60%)	51 (9.90%)	37 (6.07%)	0.089
Myocardial infarction [n (%)]	98 (19.60%)	83 (15.99%)	76 (14.76%)	74 (12.13%)	0.051
Stroke [n (%)]	71 (14.20%)	87 (16.76%)	64 (12.43%)	62 (10.16%)	0.091
Emphysema [n (%)]	37 (7.40%)	23 (4.43%)	21 (4.08%)	22 (3.61%)	0.008*
Hepatopathy [n (%)]	11 (2.20%)	9 (1.73%)	11 (2.14%)	20 (3.28%)	0.640
Cancer [n (%)]	142 (28.40%)	124 (23.89%)	113 (21.94%)	120 (19.67%)	0.025*
Gout [n (%)]	66 (13.20%)	52 (10.02%)	57 (11.07%)	75 (12.30%)	0.620
Deceased [n (%)]	230 (46.00%)	157 (30.25%)	121 (23.50%)	141 (23.11%)	<0.001*

Abbreviations: ACR, urinary albumin-to-creatinine ratio; eGFR, estimated glomerular filtration rate; PIR, ratio of family income to poverty; PNI, prognostic nutritional index; WBC, white blood cell count.

* P value < 0.05.

Figure 1. Kaplan–meier survival estimates for the PNI groups.

Table 3. Relationship between prognostic nutritional index and all-cause mortality in different models.

Variable	Crude model (HR; 95% CI; P value)	Minimally adjusted model (HR; 95% CI; P value)	Fully adjusted model (HR; 95% CI; P value)
Prognostic nutritional index	0.96 (0.94, 0.97) <0.001	0.96 (0.95, 0.98) <0.001	0.98 (0.97, 0.99) 0.009
Prognostic nutritional index (quartile)
Q4	Reference	Reference	Reference
Q3	1.03 (0.81, 1.31) 0.812	0.99 (0.78, 1.27) 0.947	0.96 (0.74, 1.24) 0.747
Q2	1.37 (1.09, 1.72) 0.007	1.32 (1.05, 1.66) 0.016	1.20 (0.93, 1.54) 0.170
Q1	2.47 (2.00, 3.05) <0.001	2.29 (1.85, 2.83) <0.001	1.64 (1.26, 2.14) <0.001
P for trend	<0.001	<0.001	<0.001

Abbreviations: HR, hazard ratio; CI, confidence interval.

The crude model was unadjusted.

The minimally adjusted model was adjusted for sex and age group.

Figure 2. Restricted cubic spline for the association between the PNI and all-cause mortality.