Appendix Table 1.
Associations between serum folate, vitamin B-12, total homocysteine levels and PHQ score: Multiple logistic and zero-inflated poisson regression models (exposures expressed as 1=upper tertile; 0=lower or middle tertile)a
| PHQ score ≥ 10 |
PHQ continuous score |
||||||||
|---|---|---|---|---|---|---|---|---|---|
| All (n=2,178) | Men (n=918) | Women (n=1,260) | All (n=2,178) | Men (n=918) | Women (n=1,260) | ||||
| Loge (OR) | 95% CI | Loge (OR) | 95% CI | Loge (OR) | 95% CI | β±SEE | β±SEE | β±SEE | |
| Serum folate (FOL) | −0.84b | (−1.47; −0.20) | 0.27 | (−0.81; 1.36) | −1.33b | (−2.28; −0.40) | −0.16±0.06b | 0.04±0.13 | −0.23±0.07b |
| Serum vitamin B-12 (B-12) | 0.08 | (−0.34; 0.50) | 0.27 | (−1.07; 1.62) | 0.02 | (−0.56; 0.61) | 0.06±0.06 | 0.04±0.14 | 0.06±0.11 |
| Serum total homocysteine (tHcy) | 0.10 | (−0.51; 0.70) | 0.58 | (−0.60; 1.76) | −0.22 | (−0.84; 0.41) | 0.03±0.10 | 0.03±0.15 | 0.03±0.08 |
| FOL×B-12 | 0.27 | (−1.03; 1.56) | −0.34 | (−1.70; 1.01) | 0.44 | (−1.20; 2.09) | 0.02±0.14 | −0.07±0.16 | 0.02±0.15 |
| FOL× tHcy | 0.56 | (−0.34; 1.47) | −0.45 | (−1.67; 0.77) | 1.03 | (−0.38; 2.45) | 0.11±0.08 | −0.14±0.13 | 0.21±0.15 |
| B-12×tHcy | −0.09 | (−0.59; 0.42) | −0.74 | (−2.14; 0.66) | 0.90 | (−0.18; 1.99) | 0.08±0.10 | 0.04±0.15 | 0.22±0.16 |
| FOL×B-12× tHcy | −0.08 | (−1.57; 1.41) | 1.32 | (−1.30; 3.94) | −1.42 | (−3.30; 0.45) | −0.16±0.20 | 0.27±0.36 | −0.49±0.28 |
Abbreviations: B-12=Serum vitamin B-12; CI=confidence interval; FOL=Serum folate; NHANES=National Health and Nutrition Examination Survey;
OR=odds ratio; SEE=Standard error of the estimate; T=tertile; tHcy=Total homocysteine level.
Values are Loge of odds ratios with 95% confidence intervals or β±SEE. Means for upper tertile of serum folate, vitamin B-12 and tHcy were 21.1, 807.2, and 11.5, respectively. Sampling design complexity is taken into account in all analyses.
P<0.05 for null hypothesis that β=0 or Loge(OR)=0 based on Wald test.
Models adjusted for socio-demographic factors: age, sex, race/ethnicity, marital status, educational level and poverty income ratio, lifestyle and health-related factors (smoking status, BMI, physical activity: Mets.hr.wk−1, recoded as “0–<5”; “5–10”; “>10”) and dietary intakes (total energy intake, alcohol, caffeine, vitamin B-6, β-carotene, vitamin C, vitamin E and n-3 HUFA intakes, expressed as tertiles).