Table 3.

Association of factors with mammographic breast density using odds ratios (OR) and 95% confidence intervals (CI), among women in Karachi, Pakistan

Variable	Category	Heterogeneously dense		Dense
		OR	95%CI	OR	95%CI
Age (years)	< 35	2.18	0.81, 5.85	12.00	4.04, 35.65
	35–45	2.93	1.65, 4.92	9.91	4.71, 20.84
	46–54	1.14	0.69, 1.87	3.29	1.58, 6.86
	55 and above	Ref		Ref
Socioeconomic status	Upper	0.94	0.38, 2.32	0.73	0.24, 2.17
	Middle	0.95	0.41, 2.22	1.00	0.37, 2.71
	Lower	Ref		Ref
Parity	Nullipara	0.95	0.47, 1.93	2.79	1.32, 5.91
	< 3	1.63	1.05, 2.53	1.94	1.10, 3.41
	> 3	Ref		Ref
AFB* (years)	< 20	0.42	0.18, 0.97	0.28	0.10, 0.76
	20–29	0.79	0.38, 1.65	0.54	0.23, 1.22
	> 30	Ref		Ref
Breastfeeding duration	< 12 months	1.13	0.65, 1.95	1.09	0.55, 2.16
	> 12 months	Ref		Ref
Age at menarche	< 12yrs	0.61	0.30, 1.23	0.56	0.25, 1.29
	12-13yrs	0.8	0.49, 1.31	0.65	0.37, 1.17
	> 14yrs	Ref		Ref
Menopause	Menopause	0.38	0.24, 0.59	0.21	0.13, 0.36
	Premenopause	Ref		Ref
Age at menopause	< 45	0.92	0.48, 1.78	2.02	0.82, 5.01
	> 45	Ref		Ref
History of benign	Yes	1.72	1.08, 2.73	2.99	1.76, 5.09
	No	Ref		Ref
Breast cancer	Yes	1.71	0.77, 1.77	0.66	0.39, 1.13
	No	Ref		Ref
BMI (kg/m2)*		0.94	0.90, 0.98	0.80	0.75, 0.86
Physical activity* (h/week)	Walking	0.99	0.89, 1.09	0.95	0.83, 1.09
	Moderate exercise	1.02	0.98, 1.05	1.00	0.96, 1.05
	Vigorous exercise	Ref		Ref
Vitamin D (ng/ml)	< 20	1.02	0.59, 1.77	1.12	0.58, 2.14
	20–30	1.39	0.68, 2.85	1.67	0.73, 3.82
	> 30	1 (Ref)		1 (Ref)

Fatty and scattered glandular combined as the reference group. BI-RADS: Breast Imaging Reporting and Data System (fatty and scattered glandular dense = categories A and B, heterogeneously dense = C, dense = D); BMI: body mass index OR: odds ratio; 95% CI: 95% confidence interval AFB Age at first birth* mean (SD)*