. Author manuscript; available in PMC: 2014 Oct 9.

Published in final edited form as: Cancer Causes Control. 2014 Apr 20;25(7):819–827. doi: 10.1007/s10552-014-0383-5

Table 2.

Plasma calculated free 25(OH)D and risk of breast cancer overall and by tumor subtypes in the NHS II

Cut-off points (pmol/L)	Quartile 1 < 13.3	Quartile 2 13.3 to < 19.2	Quartile 3 19.2 to < 25.5	Quartile 4 ≥ 25.5	Trend test p value
All cases
Cases/controls	124/145	162/147	139/146	159/146
Simple^a	1.00^Ref	1.29 (0.93–1.79)	1.15 (0.81–1.63)	1.30 (0.92–1.85)	0.26
Multivariate^b	1.00^Ref	1.24 (0.87–1.76)	1.09 (0.75–1.58)	1.21 (0.83–1.77)	0.50
Invasive
Cases/controls	89/145	107/147	98/146	104/146
Multivariate^c	1.00^Ref	1.25 (0.85–1.82)	1.14 (0.77–1.69)	1.15 (0.77–1.72)	0.69
ER+/PR+
Cases/controls	54/145	65/147	71/146	70/146
Multivariate^c	1.00^Ref	1.27 (0.81–2.00)	1.41 (0.89–2.23)	1.31 (0.82–2.09)	0.32
ER−/PR−
Cases/controls	17/145	23/147	10/146	16/146
Multivariate^d	1.00^Ref	1.26 (0.62–2.57)	0.49 (0.20–1.16)	0.85 (0.37–1.93)	0.35

Univariate conditional logistic regression model

Multivariate conditional logistic regression model adjusted for BMI at age 18 (<20, 20 to<23, ≥23 kg/m²), BMI at blood drawn (continuous), age at menarche (<12, 12, 13, >13 years), parity and age at first birth (nulliparous, 1–2 children and <25 years, 1–2 children and 25–29 years, 1–2 children and ≥30 years, ≥3 children and <25 years, ≥3 children and ≥25 years), family history of breast cancer, history of benign breast disease, and alcohol consumption at blood collection (none, 1–3 drinks/month, 1 drink/week, 2–4 drinks/week, >4 drinks/week)

Multivariate unconditional logistic regression models adjusted for the same covariates in b and matching factors: age at blood collection (continuous), race (white, other), date of blood collection (February–April, May–July, August–October, November–January), time of blood collection (1–4 a.m., 5–6 a.m., 7 a.m. to 12 p.m., treated as continuous), fasting status (>8 h, ≤8 h), luteal day (<8, ≥8, untimed collection), and menopausal status at blood collection (premenopausal, postmenopausal, unknown)

Multivariate unconditional logistic regression model adjusted for the same covariates and matching variables in c except that alcohol consumption was adjusted using three categories (none, 1–3 drinks/month, ≥1 drink/week)

Ref referent