3.1 Baseline features
Table 1 shows the baseline characteristics of the study population, which comprising 5,699 individuals,and stratified into four groups based on their Visceral Adiposity Index (VAI) scores. Of this cohort, 2,798 participants (49.1%) were male, and the average age was 49.2 ± 17.9 years. The overall prevalence of chronic diarrhea (CD) among the participants was 7.4%. Notably, the prevalence of CD escalated from 5.5% in the lowest quartile to 10.6% in the highest quartile (p < 0.0001). Individuals in the highest VAI quartile demonstrated increased levels of age, BMI, belonging to the Mexican American group, waist circumference (WC), CD, smoking, diabetes, hypertension, depression, triglycerides (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), white blood cell count (WBC), and hemoglobin (Hb). Conversely, lower CD levels were observed in non-Hispanic black individuals, those with higher education levels, higher family poverty ratios, and higher HDL-C levels. Except for gender, all variables showed statistical significance across the four VAI quartiles (p < 0.05).
Table 1. Baseline characteristics of population with different VAI levels
visceral adiposity index
|
Total(n=5699)
|
Q1(0.09≤VAI≤0.92)
(n=1425)
|
Q2(0.92<VAI≤1.48)
(n=1424)
|
Q3(1.48<VAI≤2.44)
(n=1425)
|
Q4(2.44<VAI≤12.73)
(n=1425)
|
p
|
Age, Mean ± SD
|
49.2 ± 17.9
|
45.9 ± 17.8
|
49.4 ± 18.2
|
50.4 ± 18.1
|
51.2 ± 16.9
|
< 0.001
|
Gender, n (%)
|
|
|
|
|
|
0.447
|
Male
|
2798 (49.1)
|
714 (50.1)
|
708 (49.7)
|
702 (49.3)
|
674 (47.3)
|
|
Female
|
2901 (50.9)
|
711 (49.9)
|
716 (50.3)
|
723 (50.7)
|
751 (52.7)
|
|
BMI, Median (IQR)
|
27.9 (24.3, 32.2)
|
24.9 (22.0, 28.5)
|
27.0 (23.9, 30.9)
|
29.1 (25.7, 33.3)
|
30.4 (27.1, 34.6)
|
< 0.001
|
Race, n (%)
|
|
|
|
|
|
< 0.001
|
Mexican American
|
1010 (17.7)
|
177 (12.4)
|
218 (15.3)
|
285 (20)
|
330 (23.2)
|
|
Other Hispanic
|
451 ( 7.9)
|
96 (6.7)
|
115 (8.1)
|
109 (7.6)
|
131 (9.2)
|
|
Non-Hispanic White
|
2929 (51.4)
|
676 (47.4)
|
746 (52.4)
|
728 (51.1)
|
779 (54.7)
|
|
Non-Hispanic Black
|
1080 (19.0)
|
417 (29.3)
|
281 (19.7)
|
250 (17.5)
|
132 (9.3)
|
|
Other Race
|
229 ( 4.0)
|
59 (4.1)
|
64 (4.5)
|
53 (3.7)
|
53 (3.7)
|
|
Education, n (%)
|
|
|
|
|
|
< 0.001
|
<High school
|
1544 (27.1)
|
304 (21.3)
|
359 (25.2)
|
398 (27.9)
|
483 (33.9)
|
|
≥High school
|
4155 (72.9)
|
1121 (78.7)
|
1065 (74.8)
|
1027 (72.1)
|
942 (66.1)
|
|
Family poverty ratio, n (%)
|
|
|
|
|
|
< 0.001
|
Low
|
1638 (28.7)
|
351 (24.6)
|
369 (25.9)
|
411 (28.8)
|
507 (35.6)
|
|
Medium
|
2227 (39.1)
|
551 (38.7)
|
542 (38.1)
|
600 (42.1)
|
534 (37.5)
|
|
High
|
1834 (32.2)
|
523 (36.7)
|
513 (36)
|
414 (29.1)
|
384 (26.9)
|
|
WC, Mean ± SD
|
98.9 ± 15.8
|
89.8 ± 13.6
|
96.7 ± 14.8
|
102.8 ± 15.2
|
106.5 ± 14.3
|
< 0.001
|
Chronic diarrhea, n (%)
|
424 ( 7.4)
|
79 (5.5)
|
87 (6.1)
|
107 (7.5)
|
151 (10.6)
|
< 0.001
|
Drinking, n (%)
|
4110 (72.1)
|
1060 (74.4)
|
1038 (72.9)
|
1031 (72.4)
|
981 (68.8)
|
0.008
|
Smoking, n (%)
|
|
|
|
|
|
< 0.001
|
Never
|
2985 (52.4)
|
848 (59.5)
|
751 (52.7)
|
731 (51.3)
|
655 (46)
|
|
Former
|
1487 (26.1)
|
322 (22.6)
|
361 (25.4)
|
381 (26.7)
|
423 (29.7)
|
|
Now
|
1227 (21.5)
|
255 (17.9)
|
312 (21.9)
|
313 (22)
|
347 (24.4)
|
|
Diabetes, n (%)
|
768 (13.5)
|
95 (6.7)
|
155 (10.9)
|
214 (15)
|
304 (21.3)
|
< 0.001
|
Hypertension, n (%)
|
2116 (37.1)
|
383 (26.9)
|
505 (35.5)
|
581 (40.8)
|
647 (45.4)
|
< 0.001
|
Depression, n (%)
|
448 ( 7.9)
|
87 (6.1)
|
95 (6.7)
|
108 (7.6)
|
158 (11.1)
|
< 0.001
|
HDL-C, Mean ± SD
|
1.4 ± 0.4
|
1.8 ± 0.4
|
1.5 ± 0.3
|
1.3 ± 0.3
|
1.1 ± 0.3
|
< 0.001
|
TG, Mean ± SD
|
1.4 ± 0.8
|
0.7 ± 0.2
|
1.1 ± 0.2
|
1.5 ± 0.3
|
2.4 ± 0.7
|
< 0.001
|
TC, Mean ± SD
|
5.1 ± 1.1
|
4.8 ± 1.0
|
4.9 ± 1.0
|
5.1 ± 1.1
|
5.4 ± 1.1
|
< 0.001
|
LDL-C, Mean ± SD
|
3.0 ± 0.9
|
2.7 ± 0.8
|
3.0 ± 0.9
|
3.1 ± 0.9
|
3.1 ± 1.0
|
< 0.001
|
WBC, Mean ± SD
|
6.9 ± 2.4
|
6.2 ± 1.8
|
6.6 ± 2.0
|
7.1 ± 1.9
|
7.5 ± 3.4
|
< 0.001
|
Hb, Mean ± SD
|
14.3 ± 1.6
|
14.1 ± 1.5
|
14.3 ± 1.5
|
14.3 ± 1.6
|
14.4 ± 1.6
|
< 0.001
|
Abbreviations: VAI Visceral adiposity index, SD standard deviation, BMI Body mass index, WC waist circumference, HDL-c High-density lipoprotein-cholesterol, TG Triglyceride, TC Total cholesterol, LDL-c Low-density lipoprotein-cholesterol, WBC White blood count, Hb Hemoglobin.
3.2 Association between VAI and chronic diarrhea
Table 2 presents the results from the multivariable logistic regression analysis exploring the association between VAI and CD. A higher VAI score is significantly correlated with an increased risk of CD. When analyzed as a continuous variable, the risk of CD in the total population escalates incrementally with each unit increase in VAI: by 0.18 times (OR, 1.18; 95% CI, 1.12-1.25; P<0.001) in the crude model, by 0.15 times (OR, 1.15; 95% CI, 1.08-1.22; P<0.001) in the minimally adjusted model, and by 0.12 times (OR, 1.12; 95% CI, 1.05-1.2; P=0.001) in the fully adjusted model.
As a categorical variable, individuals in the highest quartile (Q4) of VAI exhibited a 0.64 times increased risk (OR, 1.64; 95% CI, 1.2-2.24; P=0.002) of CD compared to those in the lowest quartile (Q1), after adjusting for all potential confounders in the fully adjusted model. The trend test confirmed the significance of this association (p < 0.001).
A linear relationship between VAI and the risk of CD was demonstrated in Model 4 (Figure 2), utilizing a restricted cubic spline model (P for non-linearity = 0.762, with the highest and lowest 0.5% of measures trimmed).
Table 2. Logistic regression analysis models showing the associations between visceral adiposity index and diarrhea and chronic diarrhea
|
Model 1
|
Model 2
|
Model 3
|
Model 4
|
|
OR (95%CI)
|
P value
|
OR (95%CI)
|
P value
|
OR (95%CI)
|
P value
|
OR (95%CI)
|
P value
|
VAI
|
1.18 (1.12~1.25)
|
<0.001
|
1.15 (1.08~1.22)
|
<0.001
|
1.11 (1.05~1.19)
|
0.001
|
1.12 (1.05~1.2)
|
0.001
|
Quartile
|
|
|
|
|
|
|
|
|
Q1
|
1(Ref)
|
|
1(Ref)
|
|
1(Ref)
|
|
1(Ref)
|
|
Q2
|
1.11 (0.81~1.52)
|
0.519
|
1.06 (0.77~1.45)
|
0.728
|
1.01 (0.74~1.39)
|
0.942
|
1.02 (0.74~1.42)
|
0.888
|
Q3
|
1.38 (1.02~1.87)
|
0.034
|
1.27 (0.93~1.72)
|
0.128
|
1.20 (0.88~1.63)
|
0.256
|
1.23 (0.89~1.68)
|
0.209
|
Q4
|
2.02 (1.52~2.68)
|
<0.001
|
1.77 (1.32~2.38)
|
<0.001
|
1.57 (1.16~2.12)
|
0.004
|
1.64 (1.20~2.24)
|
0.002
|
Trend.test
|
|
<0.001
|
|
<0.001
|
|
0.001
|
|
0.001
|
Model 1:Unadjusted model.
Model 2:Adjusted for the age, gender, race, education and family poverty ratio.
Model 3:Additionally adjusted for drinking, smoking, diabetes, hypertension and depression.
Model 4:Additionally adjusted for TC, LDL-C, WBC and Hb.
3.3 Subgroup analysis
Following the adjustment for multiple potential confounders, gender, age, hypertension, diabetes, and depression were employed as stratification variables to examine the trend in effect size, with a forest plot illustrating the results (Figure 3). In all subgroups, the associations were positive. There were no significant interactions observed between VAI and any of the stratification variables—age, gender, hypertension, diabetes, or depression.