TABLE 2.
Unadjusted and multivariable ORs (95% CIs) for early menopause according to quartile of total and free 25(OH)D and VDBP concentrations: NHS2 (1996–2011)1
| Quartile | ||||||
|---|---|---|---|---|---|---|
| Biomarker | n/Q1 = 169 | n/Q2 = 175 | n/Q3 = 153 | n/Q4 = 159 | P 2 | Continuous3 |
| Total 25(OH)D | ||||||
| Median, nmol/L | 44.2 | 59.8 | 71.7 | 90.4 | ||
| Cases:controls, n:n | 86:83 | 92:83 | 71:82 | 79:80 | ||
| Unadjusted OR4 (95% CI) | 1 | 1.07 (0.70, 1.64) | 0.81 (0.51, 1.29) | 0.91 (0.56, 1.48) | 0.69 | 1.02 (0.83, 1.25) |
| MV1 | 1 | 1.21 (0.75, 1.93) | 0.93 (0.56, 1.54) | 1.04 (0.60, 1.81) | 0.75 | 1.12 (0.89, 1.42) |
| MV2 | 1 | 1.18 (0.73, 1.89) | 0.88 (0.53, 1.46) | 0.96 (0.55, 1.69) | 0.70 | 1.09 (0.85, 1.38) |
| Free 25(OH)D | ||||||
| Median, pmol/L | 13.9 | 18.7 | 24.2 | 32.4 | ||
| Cases:controls, n:n | 94:83 | 91:85 | 81:80 | 62:80 | ||
| Unadjusted OR4 (95% CI) | 1 | 0.92 (0.60, 1.40) | 0.87 (0.56, 1.34) | 0.65 (0.41, 1.05) | 0.32 | 0.82 (0.67, 0.99) |
| MV1 | 1 | 1.02 (0.64, 1.62) | 0.98 (0.61, 1.57) | 0.70 (0.41, 1.20) | 0.44 | 0.85 (0.68, 1.05) |
| VDBP | ||||||
| Median, µg/mL | 145.4 | 203.0 | 248.2 | 305.3 | ||
| Cases:controls, n:n | 56:81 | 87:81 | 86:83 | 99:83 | ||
| Unadjusted OR4 (95% CI) | 1 | 1.54 (0.99, 2.41) | 1.49 (0.96, 2.34) | 1.75 (1.11, 2.77) | 0.10 | 1.16 (0.99, 1.36) |
| MV1 | 1 | 1.54 (0.94, 2.51) | 1.80 (1.10, 2.95) | 1.80 (1.09, 2.98) | 0.07 | 1.17 (0.99, 1.39) |
| MV2 | 1 | 1.50 (0.92, 2.46) | 1.77 (1.08, 2.90) | 1.77 (1.06, 2.94) | 0.09 | 1.16 (0.98, 1.38) |
1MV1 adjusted for matching factors plus physical activity (<9, 9 to <42, or ≥42 MET-h/wk), duration of breastfeeding at blood draw (0, >0–6, >6–18, or >18 mo), smoking status at blood draw (nonsmoker or current smoker), BMI (kg/m2; <25 or ≥25), and intakes of alcohol (0, 0.1–9.9, 10.0–29.9, or ≥30.0 g/d) and percentage of vegetable protein (continuous) at blood draw. MV2 adjusted for covariates in MV1 plus mutual adjustment for total 25(OH)D and VDBP. MET, metabolic equivalent task; MV, multivariable; NHS2, Nurses’ Health Study II; Q, quartile; VDBP, vitamin D–binding protein; 25(OH)D, 25-hydroxyvitamin D.
2 P values correspond to likelihood ratio tests comparing models with and without indicator variables for exposures.
3ORs correspond to a 1-SD increase in exposure.
4Model adjusted for matching factors only [i.e., age at blood collection (within 4 mo), time of day of blood collection, month of collection (within 3 mo), sample type (luteal phase or untimed), and fasting status].