Space-time clusters of breast cancer using residential histories: A Danish case–control study

BMC Cancer

Table 1 Descriptive statistics of breast cancer cases and matched controls by factors used for adjustment

Descriptive statistics		Cases	Controls
Full data set		3138	6276
Women with missing data on adjustment variables		1060	2121
Women with data on adjustment variables		2078	4155
Age at diagnosis/index date^a		62.6 (41.5 - 85.9)	62.6 (41.5 - 85.9)
Adjustment variables				p-value
Child birth yes/no		1838/240 (88%/12%)	3734 / 421 (90%/10%)	0.09^d
Number of children				0.01^e
	0	240 (12%)	421 (10%%)	-
	1	328 (16%)	623 (15%)	-
	2	953 (46%)	1910 (46%)	-
	≥3	557 (27%)	1201 (29%)	-
Age at first child birth^a,b		24.1 (18.6 - 33.5)	23.6 (18.3 - 32.7)	0.0004^e
Area-level education^a,c		6.5 (1–31)	5.9 (1–28.2)	0.007^e
Area-level income in 100.000 DKK^a		4.9 (2.9 - 7.6)	4.8 (2.8 - 7.4)	0.052^e

^aNumbers are medians (5% - 95% percentiles).
^bAmong parous women.
^cPercentage of households in the area having the highest possible educational level.
DKK: the Danish currency.
^dUnivariate χ²-test of categorical variable.
^eUnivariate Wilcoxon test of linear variables.

ISSN: 1471-2407