Atherogenic index of plasma combined with waist circumference and body mass index to predict metabolic-associated fatty liver disease

Table 1 Baseline characteristics of the study subjects

Variable	Non-MAFLD, n = 352	MAFLD, n = 512	Statistics1	P value
Demographics
Sex			χ2 = 14.020	< 0.001
Male	230 (65.3)	394 (77.0)
Female	122 (34.7)	118 (23.0)
Age in yr	37.750 ± 10.736	41.240 ± 10.852	t = -4.634	< 0.001
Age ≥ 40 yr	115 (32.7)	254 (49.6)	χ2 = 24.461	< 0.001
Age < 40 yr	237 (67.3)	258 (40.4)
Smoking history	81 (23.0)	174 (34.0)	χ2= 12.073	< 0.001
Drinking history	76 (21.6)	145 (28.3)	χ2= 4.962	0.027
Anthropometrics
WC in cm	86.240 ± 9.893	96.790 ± 8.618	t = -16.219	< 0.001
BMI in kg/m2	24.436 ± 3.169	28.028 ± 3.221	t = -16.228	< 0.001
SBP in mmHg	125.880 ± 14.883	133.610 ± 16.859	t = -6.908	< 0.001
DBP in mmHg	77.500 ± 11.658	82.950 ± 12.525	t = -6.461	< 0.001
Laboratory tests
ALT in U/L	21.0 (15.0, 30.0)	34.0 (24.0, 54.0)	Z = -12.276	< 0.001
AST in U/L	19.0 (17.0, 23.0)	23.0 (19.0, 29.0)	Z = -9.058	< 0.001
TC in mmol/L	4.539 ± 0.847	4.783 ± 0.902	t = -4.104	< 0.001
TG in mmol/L	1.1 (0.7, 1.5)	1.8 (1.3, 2.6)	Z = -13.650	< 0.001
HDL-C in mmol/L	1.351 ± 0.283	1.191 ± 0.256	t = 8.321	< 0.001
LDL-C in mmol/L	2.645 ± 0.708	2.906 ± 0.884	t = -4.568	< 0.001
FBG in mmol/L	5.2 (4.9, 5.4)	5.4 (5.1, 5.9)	Z = -7.637	< 0.001
SUA in μmol/L	332.722 ± 86.289	377.836 ± 85.859	t = -7.590	< 0.001
AIP	-0.11 (-0.30, 0.08)	0.20 (0.03, 0.39)	Z = -14.006	< 0.001

¹Comparison of significant differences between the two groups; χ² value calculated by the χ² test; Z value calculated by the Mann-Whitney U test; t value calculated by the independent samples t test. Data are presented as median and interquartile range, mean and standard deviation or frequency (percentage). MAFLD: Metabolic-associated fatty liver disease; WC: Waist circumference; BMI: Body mass index; SBP: Systolic blood pressure; DBP: Diastolic blood pressure; ALT: Alanine aminotransferase; AST: Aspartate aminotransferase; TC: Total cholesterol; TG: Triglyceride; HDL-C: High-density lipoprotein cholesterol; LDL-C: Low-density lipoprotein cholesterol; FBG: Fasting blood glucose; SUA: Serum uric acid; AIP: Atherogenic index of plasma.

Table 2 Multivariate logistic regression of atherogenic index of plasma for the risk of metabolic-associated fatty liver disease

Variable		β	SE	Wald χ2	P value	OR (95%CI)
Model 1	AIP level (per change in SD)	3.918	0.318	151.599	< 0.001	50.286 (26.953-93.819)
	Quartiles of AIP
	A1 (≤ -0.1265)	-	-	-	-	1 (Ref)
	A2 (-0.1265-0.0947)	1.241	0.209	35.108	< 0.001	3.460 (2.295-5.217)
	A3 (0.0947-0.3023)	2.323	0.226	105.794	< 0.001	10.204 (6.554-15.885)
	A4 (> 0.3022)	2.826	0.245	132.611	< 0.001	16.882 (10.436-27.311)
Model 2	AIP level (per change in SD)	3.889	0.32	147.414	< 0.001	48.874 (26.087-91.569)
	Quartiles of AIP
	A1 (≤ -0.1265)	-	-	-	-	1 (Ref)
	A2 (-0.1265-0.0947)	0.847	0.241	12.347	< 0.001	3.218 (2.124-4.876)
	A3 (0.0947-0.3023)	1.690	0.260	42.107	< 0.001	9.774 (6.256-15.270)
	A4 (> 0.3022)	2.103	0.281	55.913	< 0.001	16.514 (10.176-26.799)
Model 3	AIP level (per change in SD)	2.784	0.362	59.147	< 0.001	16.184 (7.961-32.902)
	Quartiles of AIP
	A1 (≤ -0.1265)	-	-	-	-	1 (Ref)
	A2 (-0.1265-0.0947)	0.847	0.241	12.347	< 0.001	2.334 (1.455-3.744)
	A3 (0.0947-0.3023)	1.690	0.260	42.107	< 0.001	5.421 (3.253-9.032)
	A4 (> 0.3022)	2.103	0.281	55.913	< 0.001	8.194 (4.721-14.22)
Model 4	AIP level (per change in SD)	2.519	0.371	46.230	< 0.001	12.420 (6.008-25.675)
	Quartiles of AIP
	A1 (≤ -0.1265)	-	-	-	-	1 (Ref)
	A2 (-0.1265-0.0947)	0.828	0.249	11.088	0.001	2.288 (1.4063-725)
	A3 (0.0947-0.3023)	1.642	0.268	37.636	< 0.001	5.167 (3.058-8.732)
	A4 (> 0.3022)	1.969	0.289	46.343	< 0.001	7.160 (4.062-12.62)

Model 1: Unadjusted. Model 2: Adjusted for age and sex. Model 3: Adjusted for age, sex, smoking history, drinking history, waist circumference and body mass index. Model 4: Adjusted for age, sex, smoking history, drinking history, waist circumference, body mass index, systolic blood pressure, diastolic blood pressure, alanine aminotransferase, aspartate aminotransferase, total cholesterol, triglyceride, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, fasting blood glucose, and serum uric acid. AIP: Atherogenic index of plasma; SE: Standard error; OR: Odds ratio; CI: Confidence interval; SD: Standard deviation.

Table 3 Results analysis of the receiver operating characteristic curves

Variable	AUC (95%CI)	P value	Sensitivity (%)	Specificity (%)	Youden index	Cutoff value
Total
AIP	0.780 (0.751-0.807)	< 0.0001	75.20	69.89	0.4508	0.0340
WC in cm	0.790 (0.761-0.817)	< 0.0001	85.94	58.52	0.4446	88.00
BMI in kg/m2	0.788 (0.759-0.814)	< 0.0001	83.20	59.09	0.4229	25.10
A-W-B	0.833 (0.807-0.858)1,2,3	< 0.0001	86.13	68.47	0.5460	0.5019
Male
AIP	0.755 (0.719-0.788)	< 0.0001	75.89	64.78	0.4067	0.0821
WC in cm	0.770 (0.735-0.803)	< 0.0001	72.59	67.39	0.3998	92.50
BMI in kg/m2	0.773 (0.738-0.805)	< 0.0001	72.34	68.70	0.4103	26.32
A-W-B	0.814 (0.781-0.843)1,2,3	< 0.0001	82.99	65.65	0.4865	0.5932
Female
AIP	0.819 (0.764-0.865)	< 0.0001	82.2	70.49	0.5270	-0.1390
WC in cm	0.820 (0.765-0.866)	< 0.0001	81.36	69.67	0.5103	85.50
BMI in kg/m2	0.804 (0.748-0.852)	< 0.0001	88.98	58.20	0.4718	23.34
A-W-B	0.874 (0.826-0.914)1,2,3	< 0.0001	78.81	83.61	0.6242	0.4105
Age ≥ 40 yr
AIP	0.726 (0.678-0.771)	< 0.0001	71.26	66.96	0.3822	0.0367
WC in cm	0.736 (0.688-0.780)	< 0.0001	82.68	52.17	0.3485	88.00
BMI in kg/m2	0.736 (0.688-0.780)	< 0.0001	71.26	66.96	0.3822	26.03
A-W-B	0.787 (0.742-0.828)1,2,3	< 0.0001	77.56	69.57	0.4712	0.5574
Age < 40 yr
AIP	0.816 (0.779-0.849)	< 0.0001	73.64	77.22	0.5086	0.0814
WC in cm	0.824 (0.787-0.856)	< 0.0001	89.15	61.60	0.5075	88.00
BMI in kg/m2	0.820 (0.783-0.853)	< 0.0001	83.72	66.24	0.4997	25.31
A-W-B	0.863 (0.830-0.892)1,2,3	< 0.0001	89.92	71.73	0.6165	0.4947
BMI ≥ 28 kg/m2
AIP	0.579 (0.519-0.638)	0.0849	25.63	90.91	0.1654	0.4140
WC in cm	0.597 (0.688-0.780)	0.0303	36.97	79.55	0.1652	104.50
BMI in kg/m2	0.648 (0.589-0.704)	0.0005	65.13	68.18	0.3331	29.38
A-W-B	0.644 (0.585-0.700)1	0.0007	43.28	84.09	0.2737	0.9009
BMI < 28 kg/m2
AIP	0.783 (0.747-0.816)3	< 0.0001	69.71	76.30	0.4601	0.0340
WC in cm	0.754 (0.717-0.789)	< 0.0001	78.1	63.31	0.4141	87.50
BMI in kg/m2	0.733 (0.695-0.768)	< 0.0001	77.37	59.42	0.3679	24.56
A-W-B	0.822 (0.789-0.852)1,2,3	< 0.0001	80.66	72.08	0.5273	0.4531

¹Indicates significantly larger compared with atherogenic index of plasma.

²Indicates significantly larger as compared with waist circumference.

³Indicates significantly larger as compared with body mass index.

AUC: Area under the receiver operating characteristic curve; AIP: Atherogenic index of plasma; WC: Waist circumference; BMI: Body mass index; A-W-B: Prediction model combining atherogenic index of plasma, waist circumference, and body mass index; CI: Confidence interval.

Table 4 Establishment of the logistic regression prediction model A-W-B combined with the atherogenic index of plasma, waist circumference, and body mass index

Variable	β	SE	Wald χ2	P value	OR (95%CI)
AIP	2.560	0.345	55.017	< 0.001	12.939 (6.578-25.45)
WC	0.049	0.017	7.951	0.005	1.050 (1.015-1.087)
BMI	0.170	0.051	11.087	0.001	1.186 (1.073-10311)
Constant	-8.782	1.003	76.689

AIP: Atherogenic index of plasma; WC: Waist circumference; BMI: Body mass index; SE: Standard error; OR: Odds ratio; CI: Confidence interval.

Table 5 Spearman’s correlation analysis results between various indicators (r value)

Variable	AIP	WC	BMI	A-W-B
SBP in mmHg	0.299b	0.358b	0.362b	0.392b
DBP in mmHg	0.327b	0.325b	0.315b	0.375b
ALT in U/L	0.470b	0.455b	0.451b	0.530b
AST in U/L	0.306b	0.307b	0.304b	0.351b
TC in mmol/L	0.193b	0.070a	0.056	0.132b
TG in mmol/L	0.954b	0.455b	0.430b	0.763b
HDL-C in mmol/L	-0.617b	-0.365b	-0.373b	-0.543b
LDL-C in mmol/L	0.253b	0.128b	0.105b	0.190b
FBG in mmol/L	0.294b	0.280b	0.274b	0.334b
SUA in μmol/L	0.462b	0.375b	0.358b	0.469b

^aP < 0.05.

^bP < 0.01.

SBP: Systolic blood pressure; DBP: Diastolic blood pressure; ALT: Alanine aminotransferase; AST: Aspartate aminotransferase; TC: Total cholesterol; TG: Triglyceride; HDL-C: High-density lipoprotein cholesterol; LDL-C: Low-density lipoprotein cholesterol; FBG: Fasting blood glucose; SUA: Serum uric acid; AIP: Atherogenic index of plasma; WC: Waist circumference; BMI: Body mass index; A-W-B: Prediction model combining atherogenic index of plasma, waist circumference, and body mass index.

Table 6 Data comparison between training set and validation set

Variable	Training set, n = 864	Validation set, n = 131	P value
Sex, female	240 (27.8)	38 (29.0)	0.770
Age in yr	39.820 ± 10.934	39.660 ± 10.861	0.885
Smoking history	255 (29.5)	38 (29.0)	0.906
Drinking history	221 (25.6)	24 (18.3)	0.072
WC in cm	92.490 ± 10.522	93.690 ± 10.759	0.057
BMI in kg/m2	26.563 ± 3.653	27.055 ± 3.772	0.155
SBP in mmHg	130.460 ± 16.517	129.090 ± 16.822	0.386
DBP in mmHg	80.730 ± 12.464	78.560 ± 12.192	0.063
ALT in U/L	28.0 (19.0, 42.0)	28.0 (19.0, 43.0)	0.837
AST in U/L	21.0 (18.0, 26.0)	22.0 (18.0, 26.0)	0.612
TC in mmol/L	4.683 ± 0.888	4.607 ± 0.865	0.349
TG in mmol/L	1.5 (1.0, 2.2)	1.6 (1.0, 2.5)	0.307
HDL-C in mmol/L	1.256 ± 0.279	1.241 ± 0.293	0.533
LDL-C in mmol/L	2.800 ± 0.826	2.763 ± 0.769	0.651
FBG in mmol/L	5.3 (5.0, 5.7)	5.2 (4.9, 5.8)	0.326
SUA in μmol/L	359.434 ± 88.800	342.901 ± 88.448	0.052
AIP	0.09 (-0.13, 0.30)	0.12 (-0.13, 0.33)	0.306

Data are presented as median and interquartile range, mean ± SD, or n (%). WC: Waist circumference; BMI: Body mass index; SBP: Systolic blood pressure; DBP: Diastolic blood pressure; ALT: Alanine aminotransferase; AST: Aspartate aminotransferase; TC: Total cholesterol; TG: Triglyceride; HDL-C: High-density lipoprotein cholesterol; LDL-C: Low-density lipoprotein cholesterol; FBG: Fasting blood glucose; SUA: Serum uric acid; AIP: Atherogenic index of plasma.