Table 1.

Characteristics of study participants at their baseline screening mammogram at ages 35 to 39, overall and by whether they returned to a BCSC facility for future mammography between ages 40 and 45^a

	Overall		Had future mammography at ages 40–45 as captured in the BCSC		Did not have future mammography at ages 40–45 as captured in the BCSC
	n	%^b	n	%	n	%
Total	29,390		20,192		9,198
Age at baseline mammogram
35	3,294	11.2	2,095	10.4	1,199	13.0
36	4,291	14.6	2,701	13.4	1,590	17.3
37	5,712	19.4	3,835	19.0	1,877	20.4
38	6,737	22.9	4,751	23.5	1,986	21.6
39	9,356	31.8	6,810	33.7	2,546	27.7
Race/ethnicity
White	22,888	77.9	15,794	78.2	7,094	77.1
AA	2,609	8.9	1,585	7.8	1,024	11.1
Asian	2,002	6.8	1,581	7.8	421	4.6
Hispanic	1,891	6.4	1,232	6.1	659	7.2
Education level
Less than high school graduate	1,057	4.5	681	4.1	376	5.7
High school graduate/GED	5,307	22.8	3,759	22.5	1,548	23.5
Some college/technical school	6,526	28.0	4,559	27.3	1,967	29.9
College graduate	10,388	44.6	7,700	46.1	2,688	40.9
Unknown	6,112		3,493		2,619
Rural/urban status
Urban focused	20,461	70.1	13,296	66.3	7,165	78.7
Large rural	4,178	14.3	3,232	16.1	946	10.4
Small/isolated rural	4,536	15.6	3,538	17.7	998	11.0
Unknown	215		126		89
First-degree family history of breast cancer
No	18,294	90.1	13,200	90.2	5,094	89.8
Yes	2,009	9.9	1,430	9.8	579	10.2
Unknown	9,087		5,562		3,525
Baseline mammography outcome
False positive	3,357	11.4	2,445	12.1	912	9.9
True negative	26,033	88.6	17,747	87.9	8,286	90.1
Additional screening before age 40
No	25,678	87.4	17,062	84.5	8,616	93.7
Yes	3,712	12.6	3,130	15.5	582	6.3
Number of mammograms (any type) before age 40
Baseline mammogram only	23,146	78.8	15,124	74.9	8,022	87.2
2	4,411	15.0	3,522	17.4	889	9.7
3+	1,833	6.2	1,546	7.7	287	3.1

↵^aData years: 1994–2008.
↵^bColumn percentages are calculated among the nonmissing values.