Association between endometriosis and metabolic syndrome: a cross-sectional study based on the National Health and Nutrition Examination Survey data

Figures & data

Figure 1. The flowchart of participants selection.

Table 1. Characteristics of included participants.

Variables	Total (n = 2389)	No Endometriosis (n = 2212)	Endometriosis (n = 177)	Statistics	p
Age, n (%)				χ^2 = 6.629	.010
≤ 40 years	1553 (58.16)	1465 (59.20)	88 (48.60)
> 40 years	836 (41.84)	747 (40.80)	89 (51.40)
Race, n (%)				χ^2 = 31.430	< .001
Mexican American	566 (7.86)	556 (8.54)	10 (1.55)
Other Hispanic	114 (5.52)	109 (5.91)	5 (1.88)
Non-Hispanic White	1122 (69.13)	1001 (67.53)	121 (84.00)
Non-Hispanic Black	480 (12.12)	445 (12.46)	35 (8.88)
Other Race	107 (5.37)	101 (5.55)	6 (3.69)
Education level				χ^2 = 8.989	.061
Less than 9th grade	210 (4.63)	208 (5.00)	2 (1.20)
9–11th grade	366 (11.52)	348 (11.86)	18 (8.39)
High school graduate/GED or equivalent	522 (23.37)	477 (22.67)	45 (29.87)
Some college or AA degree	777 (34.92)	710 (34.82)	67 (35.92)
College graduate or above	514 (25.55)	469 (25.65)	45 (24.62)
Marital status, n (%)				χ^2 = 5.811	.016
Married	1358 (58.87)	1245 (57.67)	113 (69.93)
Never married	1031 (41.13)	967 (42.33)	64 (30.07)
Family PIR, Mean (S.E)	3.00 (0.05)	2.98 (0.05)	3.26 (0.17)	t = −1.64	.107
Drinking, n (%)				χ^2 = 2.621	.105
No	436 (14.02)	418 (14.54)	18 (9.22)
Yes	1953 (85.98)	1794 (85.46)	159 (90.78)
Smoking, n (%)				χ^2 = 12.533	< .001
No	1472 (56.76)	1388 (58.40)	84 (41.56)
Yes	917 (43.24)	824 (41.60)	93 (58.44)
Age at menarche, n (%)				χ^2 = 4.203	.122
≤ 11 years	550 (21.42)	500 (20.84)	50 (26.79)
12–13 years	1250 (53.54)	1156 (53.47)	94 (54.17)
≥ 14 years	589 (25.04)	556 (25.69)	33 (19.04)
Gravidity, times, Mean (S.E)	2.43 (0.06)	2.42 (0.06)	2.53 (0.10)	t = −1.02	.311
Menopause, n (%)				χ^2 = 30.725	< .001
No	1964 (78.79)	1855 (80.76)	109 (60.54)
Yes	425 (21.21)	357 (19.24)	68 (39.46)
Hysterectomy or oophorectomy, n (%)				χ^2 = 132.092	< .001
No	2097 (84.75)	1996 (88.07)	101 (54.00)
Yes	292 (15.25)	216 (11.93)	76 (46.00)
Female hormones use, n (%)				χ^2 = 41.640	< .001
No	2085 (84.15)	1975 (86.69)	110 (60.65)
Yes	294 (15.27)	228 (12.78)	66 (38.37)
Unknown	10 (0.57)	9 (0.53)	1 (0.97)
Pregnancy status, n (%)				χ^2 = 2.145	.143
No	1917 (93.46)	1759 (93.13)	158 (96.49)
Yes	472 (6.54)	453 (6.87)	19 (3.51)
Diabetes drug use, n (%)				χ^2 = 0.335	.563
No	2309 (97.21)	2139 (97.29)	170 (96.51)
Yes	80 (2.79)	73 (2.71)	7 (3.49)
Dyslipidemia drug use, n (%)				χ^2 = 0.931	.335
No	2269 (94.15)	2106 (94.37)	163 (92.13)
Yes	120 (5.85)	106 (5.63)	14 (7.87)
Hypertension drug use, n (%)				χ^2 = 1.148	.284
No	2121 (87.76)	1979 (88.03)	142 (85.22)
Yes	268 (12.24)	233 (11.97)	35 (14.78)
WC, Mean (S.E)	91.78 (0.40)	91.51 (0.42)	94.31 (1.24)	t = −2.18	.034
SBP, Mean (S.E)	113.99 (0.36)	113.66 (0.37)	117.08 (1.21)	t = −2.75	.008
DBP, Mean (S.E)	70.34 (0.31)	70.06 (0.32)	72.91 (0.97)	t = −2.88	.005
TG, mmol/L, Mean (S.E)	1.38 (0.03)	1.33 (0.02)	1.87 (0.23)	t = −2.30	.025
LDL-C, mmol/L, Mean (S.E)	2.97 (0.03)	2.96 (0.03)	3.09 (0.07)	t = −1.81	.075
HDL-C, mmol/L, Mean (S.E)	1.48 (0.01)	1.48 (0.01)	1.45 (0.04)	t = 0.76	.449
FPG, mg/dL, Mean (S.E)	94.74 (0.55)	94.62 (0.54)	95.84 (2.28)	t = −0.53	.596
Total energy, kcal, Mean (S.E)	1960.89 (16.02)	1965.52 (18.65)	1918.04 (60.87)	t = 0.69	.494
Metabolic syndrome, n (%)				χ^2 = 5.280	.022
No	1783 (75.22)	1666 (76.08)	117 (67.28)
Yes	606 (24.78)	546 (23.92)	60 (32.72)

Mean (S.E): mean (standard error); GED: General Educational Development; AA: Associate of Arts; PIR: poverty income ratio; WC: waist circumference; SBP: systolic blood pressure; DBP: diastolic blood pressure; TG: triglyceride; LDL-C: low-density lipoprotein cholesterol; HDL-C: high-density lipoprotein cholesterol; FPG: fasting plasma glucose.

Table 2. Association between endometriosis and metabolic syndrome.

Variables	Unadjusted Model		Model 1		Model 2
	OR (95%CI)	p	OR (95%CI)	p	OR (95%CI)	p
Non-endometriosis	Ref		Ref		Ref
Endometriosis	1.55 (1.06, 2.25)	.024	1.55 (1.01, 2.35)	.043	1.47 (0.96, 2.25)	.076

Abbreviation. OR: odds ratio; CI: confidence interval.

Note. Model 1 adjusted age, race, education level, family PIR, smoking, age at menarche, gravidity, menopause, female hormones use, dyslipidemia drug use.

Model 2 adjusted age, race, education level, family PIR, smoking, age at menarche, gravidity, menopause, female hormones use, dyslipidemia drug use, hysterectomy or oophorectomy.

Table 3. Association between endometriosis and metabolic syndrome indicators.

Variables	Unadjusted model		Model 1		Model 2
	β (95%CI)	p	β (95%CI)	p	β (95%CI)	p
WC^a	2.80 (0.22, 5.37)	.034	4.42 (−0.14, 8.98)	0.057	4.48 (−0.06, 9.02)	.053
SBP^b	3.42 (0.93, 5.91)	.008	3.21 (−1.35, 7.77)	0.165	2.62 (−2.08,7.32)	.268
DBP^c	2.87 (0.88, 4.87)	.006	2.28 (−1.32, 5.88)	0.210	1.30 (−2.17, 4.77)	.456
FPG^d	1.23 (−3.39, 5.84)	.597	2.14 (−4.75, 9.03)	0.537	1.00 (−5.82, 6.41)	.770
TG^e	0.54 (0.07, 1.01)	.025	0.42 (0.08, 0.76)	0.015	0.38 (0.06, 0.70)	.023
HDL-C^f	−0.03 (−0.12, 0.05)	.449	−0.03 (−0.84, 0.79)	0.470	−0.03 (−0.12,0.05)	.412

Abbreviation. CI: confidence interval; WC: waist circumference; SBP: systolic blood pressure; DBP: diastolic blood pressure; FPG: fasting plasma glucose; TG: triglyceride; HDL-C: high-density lipoprotein cholesterol.

Note. Model^1a adjusted age, race, education level, family PIR, drinking, age at menarche, gravidity, menopause, female hormones use, pregnancy status, diabetes drug use, dyslipidemia drug use, and hypertension drug use;.

Model^1b age, race, education level, gravidity, menopause, female hormones use, pregnancy status, diabetes drug use, dyslipidemia drug use, and hypertension drug.

Model^1c adjusted age, race, marital status, family PIR, gravidity, menopause, female hormones use, pregnancy status, dyslipidemia drug use, hypertension drug use, and total energy.

Model^1d adjusted age, race, education level, age at menarche, menopause, female hormones use, pregnancy status, dyslipidemia drug use, hypertension drug use, and diabetes drug use.

Model^1e adjusted age, race, education level, family PIR, smoking, age at menarche, gravidity, menopause, female hormones use, pregnancy status, dyslipidemia drug use, hypertension drug use, and diabetes drug use.

Model^1f adjusted age, race, education level, family PIR, drinking, smoking, age at menarche, gravidity, pregnancy status, dyslipidemia drug use, hypertension drug use, and diabetes drug use.

Model 2 adjusted hysterectomy or oophorectomy based on Model 1.

Data availability statement

The datasets generated and/or analyzed in this study are available in the NHANES database, https://wwwn.cdc.gov/nchs/nhanes/.