American Association for Cancer Research

Table 1

Demographic characteristics and breast cancer risk factors by duration of NSAID exposure in the WHI Observational Study

Characteristic or breast cancer risk factor^a	Duration of NSAID exposure
		0–11 mo			1 to <5 yr			>5 yr		Total
		n	%	n	%	n	%	n	%
Age at screening, yr
50–59	18,999	72.0	3,207	12.2	4,176	15.8	26,382	32.7
60–69^b	23,586	66.3	5,607	15.8	6,401	18.0	35,594	44.1
70–79^b	11,517	61.4	3,433	18.3	3,815	20.3	18,765	23.2
Race/ethnicity
White	43,723	65.1	10,569	15.7	12,884	19.2	67,176	83.2
Black^b	4,834	74.3	893	13.7	775	11.9	6,502	8.1
Hispanic^b	2,404	76.5	390	12.4	347	11.0	3,141	3.9
Native American	246	69.7	45	12.7	62	17.6	353	0.4
Asian/Pacific Islander^b	2,088	85.8	195	8.0	151	6.2	2,434	3.0
Unknown^b	807	71.1	155	13.7	173	15.2	1,135	1.4
Education
≤HS diploma/GED	11,173	65.2	2,817	16.4	3,143	18.3	17,133	21.4
Some school after HS	19,159	65.7	4,568	15.7	5,418	18.6	29,145	36.4
College degree or higher^b	23,321	69.0	4,763	14.1	5,725	16.9	33,809	42.2
BMI (kg/m²)
<27	31,622	69.2	6,366	13.9	7,710	16.9	45,698	57.3
≥27^b	21,825	64.0	5,756	16.9	6,520	19.1	34,101	42.7
HRT use (ever)
No	22,340	70.3	4,514	14.2	4,915	15.5	31,769	39.3
Yes^b	31,762	64.9	7,733	15.8	9,477	19.4	48,972	60.7
Family history of breast cancer
No	41,813	67.4	9,347	15.1	10,890	17.6	62,050	81.2
Yes	9,407	65.7	2,203	15.4	2,710	18.9	14,320	18.8
Parous under age 30
No	11,204	69.3	2,265	14.0	2,688	16.6	16,157	22.3
Yes^b	37,228	66.0	8,759	15.5	10,406	18.5	56,393	77.7
Episodes/wk of exercise (≥20 min)
<2	27,105	65.8	6,420	15.6	7,649	18.6	41,174	51.6
≥2^b	26,266	68.1	5,706	14.8	6,623	17.2	38,595	48.4
Total	54,102	67.0	12,247	15.2	14,292	17.8	80,741	100.0

Characteristic or breast cancer risk factor^a	Duration of NSAID exposure
		0–11 mo			1 to <5 yr			>5 yr		Total
		n	%	n	%	n	%	n	%
Age at screening, yr
50–59	18,999	72.0	3,207	12.2	4,176	15.8	26,382	32.7
60–69^b	23,586	66.3	5,607	15.8	6,401	18.0	35,594	44.1
70–79^b	11,517	61.4	3,433	18.3	3,815	20.3	18,765	23.2
Race/ethnicity
White	43,723	65.1	10,569	15.7	12,884	19.2	67,176	83.2
Black^b	4,834	74.3	893	13.7	775	11.9	6,502	8.1
Hispanic^b	2,404	76.5	390	12.4	347	11.0	3,141	3.9
Native American	246	69.7	45	12.7	62	17.6	353	0.4
Asian/Pacific Islander^b	2,088	85.8	195	8.0	151	6.2	2,434	3.0
Unknown^b	807	71.1	155	13.7	173	15.2	1,135	1.4
Education
≤HS diploma/GED	11,173	65.2	2,817	16.4	3,143	18.3	17,133	21.4
Some school after HS	19,159	65.7	4,568	15.7	5,418	18.6	29,145	36.4
College degree or higher^b	23,321	69.0	4,763	14.1	5,725	16.9	33,809	42.2
BMI (kg/m²)
<27	31,622	69.2	6,366	13.9	7,710	16.9	45,698	57.3
≥27^b	21,825	64.0	5,756	16.9	6,520	19.1	34,101	42.7
HRT use (ever)
No	22,340	70.3	4,514	14.2	4,915	15.5	31,769	39.3
Yes^b	31,762	64.9	7,733	15.8	9,477	19.4	48,972	60.7
Family history of breast cancer
No	41,813	67.4	9,347	15.1	10,890	17.6	62,050	81.2
Yes	9,407	65.7	2,203	15.4	2,710	18.9	14,320	18.8
Parous under age 30
No	11,204	69.3	2,265	14.0	2,688	16.6	16,157	22.3
Yes^b	37,228	66.0	8,759	15.5	10,406	18.5	56,393	77.7
Episodes/wk of exercise (≥20 min)
<2	27,105	65.8	6,420	15.6	7,649	18.6	41,174	51.6
≥2^b	26,266	68.1	5,706	14.8	6,623	17.2	38,595	48.4
Total	54,102	67.0	12,247	15.2	14,292	17.8	80,741	100.0

NSAID exposure includes aspirin, ibuprofen, prescription NSAIDs, and the related analgesic, acetaminophen. Subgroup comparisons of the distribution of duration of NSAID exposure were assessed using χ² tests. Each subgroup is compared with the underlined reference subgroup.

Subgroup comparisons with P < 0.0001.

HS, high school; GED, General Equivalency Diploma.

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