Table 2.

Results of the matched logistic regression evaluating the association between screening attendance and breast cancer mortality.

Exposure	Category of exposure	Controls (n = 15,202)	Cases (n = 8288)	OR (95% CI)	OR (95% CI) corrected for self-selectiona	OR (95% CI) corrected for self-selectionb
Ever screened	No	1803	1 741	1.00	–	–
	Yes	13,399	6 547	0.49 (0.45–0.53)	0.62 (0.56–0.69)	0.63 (0.55–0.71)

^aSelf-selection correction performed using our first method (variant of Duffy et al.¹⁵), with the OR of 0.78 associated with participation in cervical screening.

^bSelf-selection correction performed using our second method (Duffy et al.¹⁵).