Table 2.

Adjusted relative risks of cholecystectomy according to statin use among US women in the Nurses’ Health Study: retrospective analysis ^a

	Nonuse	Current use
Variable		< 2 years	≥ 2 yearsc	Total
Cases	2,412	113	54	167
Person-years	283,633	13,907	7,657	21,564
Model 1: Age-adjusted (95% C.I.)b	1.00 (referent)	0.97 (0.80, 1.18)	0.93 (0.71, 1.22)	0.96 (0.82, 1.12)
Model 2: Multivariate (95% C.I.)b	1.00 (referent)	0.83 (0.68, 1.01)	0.81 (0.62, 1.06)	0.82 (0.70, 0.96)

Model 2: Relative risk adjusting for age, time period, body mass index at the beginning of each two-year follow-up interval, weight change in the previous two years, parity, oral contraceptive use, hormone replacement therapy, physical activity, pack-years of smoking, thiazide diuretics, non-steroidal anti-inflammatory drugs, intake of total energy, energy-adjusted dietary fiber, energy-adjusted protein, energy-adjusted carbohydrate, alcohol, coffee, saturated fat, trans fat, and polyunsaturated fat.

^aRetrospective assessment between 1994 and 2000

^bC.I. = confidence interval.

^cThe categories of 2-4 years and >4 years were collapsed into one category due to few cases in the category of >4 years.