Predicted 25-hydroxyvitamin D in relation to incidence of breast cancer in a large cohort of African American women

Table 3 Cumulative predicted vitamin D status in relation to breast cancer incidence, within strata of age and vitamin D supplement use

Predicted 25(OH)D (quartiles)	Breast cancer cases	Person-years	MV^a IRR	95 % CI	P trend
Age <45 years
4 (highest)	86	89,683	1.00	Ref	0.20
3	100	89,686	1.20	0.89, 1.62
2	98	89,675	1.19	0.87, 1.63
1 (lowest)	107	89,651	1.28	0.90, 1.82
Age ≥45 years
4 (highest)	262	93,921	1.00	Ref	0.045
3	275	93,922	1.13	0.95, 1.35
2	254	93,949	1.09	0.91, 1.31
1 (lowest)	272	93,924	1.25	1.03, 1.51
BMI^b <25 kg/m²
4 (highest)	126	72,829	1.00	Ref	0.99
3	112	72,853	0.98	0.75, 1.27
2	130	72,830	1.13	0.87, 1.46
1 (lowest)	133	72,824	1.09	0.83, 1.42
BMI^b 25 to <30 kg/m²
4 (highest)	133	57,686	1.00	Ref	0.89
3	126	57,701	1.03	0.80, 1.32
2	114	57,708	0.96	0.75, 1.25
1 (lowest)	121	57,708	1.04	0.80, 1.35
BMI^b ≥30 kg/m²
4 (highest)	108	53,074	1.00	Ref	0.0003
3	109	53,078	1.19	0.91, 1.56
2	115	53,065	1.36	1.04, 1.79
1 (lowest)	127	53,054	1.66	1.25, 2.19
No vitamin D supplementation
4 (highest)	270	156,422	1.00	Ref	0.048
3	302	156,416	1.10	0.93, 1.30
2	297	156,415	1.06	0.89, 1.27
1 (lowest)	338	156,372	1.23	1.02, 1.49
Vitamin D supplementation, yes
4 (highest)	53	27,203	1.00	Ref	0.31
3	60	27,206	1.13	0.77, 1.65
2	64	27,201	1.14	0.77, 1.70
1 (lowest)	70	27,176	1.25	0.82, 1.90

^aAdjusted for age (continuous), family history of breast cancer, age at menarche, age at menopause, parity, age at first birth, oral contraceptive use, body mass index (BMI), and use of estrogen and progesterone female hormones. ^bAnalyses stratified by baseline BMI group were also adjusted for continuous BMI
25(OH)D 25-hydroxyvitamin D, IRR incident rate ratio, MV Multivariate model, CI Confidence interval

ISSN: 1465-542X