Table 2.

ORs and 95% CIs for CVDs according to BLL stratified by vitamin B6 deficiency and median value of vitamin B6

Lead (ug/dL) Quartile Range	Total		Crude			Model 1			Model 2			Model 3
	CVD (n (%))	No CVD (n (%))	OR (95% CI)	P value	P trend	OR (95% CI)	P value	P trend	OR (95% CI)	P value	P trend	OR (95% CI)	P value	P trend
Overall
Q1: 0.18–0.92	39 (3.4)	1096 (96.6)	1 (ref)		<0.0001	1 (ref)		0.02	1 (ref)		0.01	1 (ref)		0.006
Q2: 0.93–1.49	85 (7.6)	1029 (92.4)	2.4 (1.3 to 4.7)	0.008		0.9 (0.5 to 1.7)	0.8		1.1 (0.6 to 2.1)	0.8		1.1 (0.6 to 2.0)	0.9
Q3: 1.50–2.36	160 (14.3)	957 (85.7)	4.7 (2.5 to 8.7)	<0.0001		1.3 (0.7 to 2.4)	0.3		1.6 (0.7 to 3.1)	0.3		1.6 (0.9 to 2.9)	0.1
Q4: 2.37–26.4	213 (19.1)	903 (80.9)	6.8 (4.0 to 11.1)	<0.0001		1.3 (0.9 to 2.0)	0.2		1.7 (0.9 to 2.9)	0.06		1.7 (1.1 to 2.5)	0.01
Stratified by vitamin B6 deficiency (plasma PLP<20 nmol/L)
Vitamin B6-normal
Q1: 0.18–0.92	32 (3.3)	930 (96.7)	1 (ref)		<0.0001	1 (ref)		0.02	1 (ref)		0.01	1 (ref)		0.008
Q2: 0.93–1.49	64 (6.7)	892 (93.3)	2.0 (1.0 to 4.0)	0.0600		0.7 (0.3 to 1.4)	0.3		0.8 (0.4 to 1.8)	0.6		0.8 (0.4 to 1.8)	0.7
Q3: 1.50–2.36	119 (12.5)	831 (87.5)	3.9 (1.9 to 7.7)	0.0001		1.0 (0.5 to 1.9)	0.9		1.1 (0.5 to 2.4)	0.9		1.2 (0.6 to 2.3)	0.6
Q4: 2.37–26.4	161 (17.4)	762 (82.6)	5.7 (3.3 to 10.0)	<0.0001		1.0 (0.6 to 1.7)	0.8		1.3 (0.7 to 2.3)	0.4		1.4 (1.0 to 2.1)	0.08
Vitamin B6-deficiency
Q1: 0.18–0.92	7 (4.0)	166 (96.0)	1 (ref)		0.0002	1 (ref)		0.2	1 (ref)		0.2	1 (ref)		0.1
Q2: 0.93–1.49	21 (13.3)	137 (86.7)	6.9 (2.7 to 17.9)	<0.0001		2.6 (1.2 to 5.9)	0.02		4.2 (1.4 to 12.0)	0.008		3.1 (0.9 to 10.6)	0.07
Q3: 1.50–2.36	41 (24.5)	126 (75.5)	11.8 (5.0 to 28.1)	<0.0001		3.4 (1.3 to 9.0)	0.01		7.3 (2.0 to 27.3)	0.003		6.5 (1.4 to 30.8)	0.02
Q4: 2.37–26.4	52 (26.9)	141 (73.1)	14.4 (4.9 to 42.2)	<0.0001		3.5 (1.1 to 11.3)	0.04		7.3 (1.6 to 32.2)	0.009		5.5 (1.4 to 21.7)	0.01
P value for interaction*					0.06			0.2			0.3			0.4
Stratified by median value of vitamin B6 deficiency (plasma PLP=42.5 mol/L)
Vitamin B6≥Median
Q1: 0.18–0.92	16 (2.9)	539 (97.1)	1 (ref)		<0.0001	1 (ref)		0.9	1 (ref)		0.8	1 (ref)		0.9
Q2: 0.93–1.49	37 (6.4)	545 (93.6)	2.5 (1.1 to 5.8)	0.03		0.9 (0.4 to 1.8)	0.8		0.9 (0.4 to 1.9)	0.8		1.0 (0.4 to 2.4)	0.9
Q3: 1.50–2.36	58 (9.8)	534 (90.2)	3.9 (1.9 to 8.3)	0.0004		1.1 (0.5 to 2.3)	0.8		1.0 (0.5 to 2.1)	0.9		1.1 (0.5 to 2.6)	0.8
Q4: 2.37–26.4	70 (13.6)	445 (86.4)	5.3 (2.7 to 10.7)	<0.0001		1.0 (0.5 to 1.9)	0.9		0.9 (0.5 to 1.8)	0.7		1.0 (0.5 to 2.3)	0.9
Vitamin B6<Median
Q1: 0.18–0.92	23 (4.0)	557 (96.0)	1 (ref)		<0.0001	1 (ref)		0.02	1 (ref)		0.07	1 (ref)		0.004
Q2: 0.93–1.49	48 (9.0)	484 (91.0)	2.4 (1.1 to 5.5)	0.03		1.0 (0.4 to 2.2)	0.9		1.4 (0.5 to 3.4)	0.5		1.2 (0.4 to 3.2)	0.7
Q3: 1.50–2.36	102 (19.4)	423 (80.6)	5.6 (2.4 to 13.0)	<0.0001		1.6 (0.7 to 3.5)	0.2		2.2 (0.8 to 6.4)	0.1		2.1 (0.7 to 6.3)	0.2
Q4: 2.37–26.4	143 (23.8)	458 (76.2)	7.8 (3.7 to 16.4)	<0.0001		1.7 (0.8 to 3.4)	0.1		2.8 (1.1 to 6.9)	0.003		2.7 (1.1 to 7.2)	0.04
P value for interaction*					0.009			0.01			0.005			0.003

Model 1: adjusted for all the sociodemographic variables (age, gender, race, education, family income).

Model 2: further adjusted for lifestyle variables (smoking, alcohol use, BMI, activity level, dietary supplement).

Model 3: further adjusted for stress variables, comorbidities, and biomarkers (sleep, depression, hypertension, diabetes, CRP, homocysteine, cholesterol).

Bold texts indicate significant p value, defined as p < 0.05.

*P value for interaction was calculated by adding and testing the significance of the interaction term (vitamin B6 deficiency* BLL/ median vitamin B6 *BLL) in the overall regression model.

BLL, blood lead level; BMI, body mass index; CRP, C reactive protein; CVD, cardiovascular disease; PLP, pyridoxal 5'-phosphate.