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.