Table 4.

Adjusted Longitudinal Analyses of Measures of Mammographic Density (Natural Logarithm Scale)^a by Changes of Physical Activity Indices, Study of Women's Health Across the Nation, 1996–2004

Physical Activity Indexb	Dense Area		Nondense Area		Total Area
	β	95% Confidence Interval	β	95% Confidence Interval	β	95% Confidence Interval
Total activity	0.0019	−0.0009, 0.0046	−0.0030	−0.0049, −0.0011	−0.0014	−0.0025, −0.0003
Sports/exercise	0.0029	−0.0016, 0.0075	−0.0030	−0.0061, 0.0001	−0.0012	−0.0030, 0.0006
Daily routine	0.0017	−0.0045, 0.0078	−0.0060	−0.0101, −0.0018	−0.0030	−0.0054, −0.0006
Household/caregiving	0.0024	−0.0035, 0.0083	−0.0039	−0.0079, 0.0002	−0.0013	−0.0037, 0.0010

^aValues are maximum likelihood estimates of coefficients for modification to annual change in dependent variables (dense, nondense, and total area) and 95% confidence intervals from mixed-effects regression models. The dependent variables, originally measured on a centimeter-squared scale, were log transformed to normalize distribution. Single models for each mammographic density measure were adjusted for age, body mass index, menopausal status, race/ethnicity, study site, parity, past use of hormones (contraceptive and postmenopausal hormones), smoking, change in body mass index, and change in menopausal status.

^bOne unit change in index measured on a 1–15 scale for total activity and a 1–5 scale for individual domains.