The systemic immune-inflammation index was non-linear associated with all-cause mortality in individuals with nonalcoholic fatty liver disease

Figures & data

Figure 1. The visual flow-process diagram of this study.

Table 1. Baseline characteristics of NAFLD individuals according to systemic immune-inflammation index quartiles, weighted.

	Q1 (<8.4)	Q2 (8.4–8.9)	Q3 (8.9–9.4)	Q4 (>9.4)	p For trend
Age (years)	50.19 (49.28, 51.10)	50.08 (49.33, 50.84)	49.64 (48.94, 50.35)	50.52 (49.58, 51.45)	0.7035
BMI (kg/m^2)	32.39 (32.13, 32.65)	32.55 (32.26, 32.84)	33.13 (32.85, 33.41)	34.74 (34.36, 35.12)	<0.0001
Waist circumference (cm)	107.03 (106.33, 107.73)	107.67 (106.99, 108.35)	108.88 (108.26, 109.51)	111.54 (110.73, 112.35)	<0.0001
Family poverty income ratio	2.90 (2.79, 3.01)	3.07 (2.98, 3.17)	3.02 (2.91, 3.12)	2.94 (2.82, 3.07)	0.9219
Total cholesterol (mg/dL)	196.47 (194.56, 198.38)	198.02 (195.83, 200.21)	198.70 (196.71, 200.68)	196.71 (194.74, 198.69)	0.8212
ALT(U/L)	29.60 (28.76, 30.44)	29.18 (28.43, 29.93)	28.52 (27.57, 29.48)	26.53 (25.65, 27.42)	<0.0001
AST(U/L)	26.53 (26.00, 27.06)	25.56 (25.19, 25.93)	25.44 (24.88, 26.01)	24.60 (24.02, 25.17)	<0.0001
HbA1c (%)	5.84 (5.79, 5.88)	5.79 (5.73, 5.84)	5.78 (5.74, 5.83)	5.89 (5.83, 5.94)	0.1711
HDL cholesterol (mg/dL)	48.51 (47.74, 49.29)	47.94 (47.27, 48.61)	48.22 (47.62, 48.81)	48.89 (48.17, 49.61)	0.324
Creatinine (mg/dL)	0.92 (0.91, 0.93)	0.90 (0.89, 0.92)	0.90 (0.88, 0.91)	0.92 (0.90, 0.94)	0.9956
Sex
Female	48.99 (46.66, 51.32)	51.63 (49.16, 54.09)	53.10 (50.81, 55.38)	61.51 (59.07, 63.88)	<0.0001
Male	51.01 (48.68, 53.34)	48.37 (45.91, 50.84)	46.90 (44.62, 49.19)	38.49 (36.12, 40.93)	<0.0001
Race
Mexican American	9.30 (7.50, 11.49)	8.77 (6.96, 10.99)	9.22 (7.45, 11.36)	7.99 (6.33, 10.04)	0.1069
Non-Hispanic Black	22.08 (18.83, 25.71)	11.65 (9.89, 13.69)	9.73 (8.23, 11.48)	9.11 (7.56, 10.93)	<0.0001
Non-Hispanic White	58.47 (53.68, 63.11)	67.91 (64.27, 71.33)	70.87 (67.08, 74.38)	73.13 (69.43, 76.53)	<0.0001
Other	10.15 (8.38, 12.24)	11.67 (10.04, 13.53)	10.18 (8.42, 12.26)	9.78 (8.20, 11.62)	0.3524
Education
Less than high school	20.24 (17.99, 22.69)	17.11 (15.16, 19.24)	16.30 (14.29, 18.54)	17.73 (15.61, 20.07)	0.0696
High school	23.20 (21.09, 25.46)	21.86 (19.51, 24.41)	23.42 (21.11, 25.89)	25.81 (23.78, 27.95)	0.0274
High school above	56.56 (53.38, 59.69)	61.03 (58.18, 63.82)	60.28 (57.07, 63.41)	56.46 (53.63, 59.25)	0.7192
Marital status
Unmarried	31.98 (29.60, 34.46)	29.09 (26.93, 31.36)	31.85 (29.89, 33.87)	36.44 (33.97, 38.99)	0.0005
Married	68.02 (65.54, 70.40)	70.91 (68.64, 73.07)	68.15 (66.13, 70.11)	63.56 (61.01, 66.03)	0.0005
Smoking
Never	60.4 (57.7, 63.0)	59.5 (56.9, 62.0)	58.7 (56.0, 61.4)	56.0 (53.6, 58.4)	0.0112
Former	26.0 (23.7, 28.3)	28.0 (25.6, 30.4)	26.4 (24.3, 28.5)	27.6 (25.1, 30.2)	0.5808
Now	13.6 (11.9, 15.5)	12.6 (11.1, 14.2)	14.9 (13.3, 16.8)	16.4 (14.7, 18.2)	0.0034
Asthma
No	85.47 (83.65, 87.11)	86.86 (85.39, 88.20)	83.77 (81.72, 85.62)	82.09 (79.98, 84.02)	0.0023
Yes	14.53 (12.89, 16.35)	13.14 (11.80, 14.61)	16.23 (14.38, 18.28)	17.91 (15.98, 20.02)	0.0023
CVD
No	88.99 (87.50, 90.32)	90.49 (89.29, 91.57)	90.74 (89.44, 91.89)	87.49 (86.06, 88.79)	0.1264
Yes	11.01 (9.68, 12.50)	9.51 (8.43, 10.71)	9.26 (8.11, 10.56)	12.51 (11.21, 13.94)	0.1264
Diabetes
No	80.89 (79.00, 82.66)	82.42 (80.66, 84.05)	81.18 (79.45, 82.79)	77.52 (75.33, 79.57)	0.0066
Yes	19.11 (17.34, 21.00)	17.58 (15.95, 19.34)	18.82 (17.21, 20.55)	22.48 (20.43, 24.67)	0.0066
Cancer
No	90.81 (89.10, 92.28)	90.87 (89.46, 92.11)	89.85 (88.10, 91.37)	88.42 (86.83, 89.83)	0.0168
Yes	9.19 (7.72, 10.90)	9.13 (7.89, 10.54)	10.15 (8.63, 11.90)	11.58 (10.17, 13.17)	0.0168
Hypertension
No	53.81 (51.56, 56.03)	54.07 (51.42, 56.71)	52.31 (50.28, 54.33)	48.25 (45.46, 51.04)	0.0007
Yes	46.19 (43.97, 48.44)	45.93 (43.29, 48.58)	47.69 (45.67, 49.72)	51.75 (48.96, 54.54)	0.0007
Advanced fibrosis
No	98.33 (97.76, 98.75)	97.22 (96.10, 98.02)	97.15 (96.00, 97.99)	96.00(94.80, 96.93)	0.0001
Yes	1.67 (1.25, 2.24)	2.78 (1.98, 3.90)	2.85 (2.01, 4.00)	4.00(3.07, 5.20)	0.0001

Figure 2. Cox cumulative hazard function for all-cause death stratified by log₂-SII quartiles. Participants with the highest concentrations of log₂-SII (quartile 4) exhibited remarkably worse outcome compared to individuals with lower log₂-SII concentrations.

Table 2. Associations of the SII with all-cause mortality in individuals with NAFLD.

	Non-adjusted	Adjust I	Adjust II
Log SII	1.45 (1.31, 1.59); <0.0001	1.43 (1.29, 1.58); <0.0001	1.41 (1.26, 1.57); <0.0001
Log SII quartile
Q1	1 (Reference)	1 (Reference)	1 (Reference)
Q2	0.91 (0.73, 1.14); 0.4264	1.02 (0.80, 1.30); 0.8752	1.03 (0.79, 1.35); 0.8390
Q3	1.04 (0.84, 1.29); 0.7153	1.17 (0.92, 1.48); 0.1960	1.15 (0.89, 1.50); 0.2907
Q4	1.69 (1.39, 2.06); <0.0001	1.86 (1.50, 2.30); <0.0001	1.86 (1.47, 2.37); <0.0001
p For trend	<0.001	<0.001	<0.001

Non-adjusted model adjust for: None.

Adjust I model adjust for: age, sex, race, BMI, waist circumference, marital status, education, smoking and family poverty income ratio.

Adjust II model adjust for: age, sex, race, BMI, waist circumference, marital status, education, smoking and family poverty income ratio, asthma, cancer, diabetes; hypertension, smoking, creatinine, cholesterol, ALT, AST, HbA1c, HDL, creatinine and advanced fibrosis.

Figure 3. Relationship between log₂-SII and all-cause mortality by smooth curve fitting. Adjustment for age, sex, race, BMI, waist circumference, marital status, education, smoking and family poverty income ratio, asthma, cancer, diabetes; hypertension, smoking, creatinine, cholesterol, ALT, AST, HbA1c, HDL and creatinine. The red line demonstrates the risk of mortality, and the blue dotted lines illustrate its 95% confidence interval.

Table 3. Threshold analysis for the relationship between log₂-SII and all-cause mortality in patients with NAFLD.

Models	Adjusted HR (95% CI); p-value
Model I
One line slope	1.40 (1.25, 1.56); <0.001
Model II
Turning point (K)	8.8
<8.8	0.90 (0.71, 1.15); 0.419
>8.8	1.73 (1.49, 2.02); <0.001
HR between <8.8 and >8.8	1.92 (1.37, 2.69); 0.0002
Logarithmic likelihood ratio test	<0.001

Adjust for: age, sex, race, BMI, waist circumference, marital status, education, smoking and family poverty income ratio, asthma, cancer, diabetes; hypertension, smoking, creatinine, cholesterol, ALT, AST, HbA1c, HDL, creatinine and advanced fibrosis.

Figure 4. Stratification analysis of log₂-SII with all-cause mortality in NAFLD.

Data availability statement

A publicly available dataset was analyzed in this study. The National Health and Nutrition Examination Survey dataset is publicly available at https://www.cdc.gov/nchs/nhanes/index.htm.