Table 2. Numbers and percentages of cases and controls and univariate and multivariate odds ratios for breast cancer recurrence.

Medication-taking behaviour	Cases (%)a (n=94)	Controls (%)a (n=458)	Univariate odds ratio (95% CI)	Multivariate odds ratio (95% CI)b
Persistence and compliance
Hormonal therapy persistencec,d
Persistent	86 (91.5)	444 (96.9)	Ref	Ref
Non-persistent (>180 day gap)	8 (8.5)	14 (3.1)	3.00 (1.18, 7.60)	2.88 (1.11, 7.46)
Hormonal therapy compliancee,f
High (98–100%)	30 (31.9)	154 (33.6)	Ref	Ref
Intermediate (90–98%)	28 (29.8)	156 (34.1)	0.96 (0.53, 1.71)	0.95 (0.53, 1.71)
Low (0–90%)	36 (38.3)	148 (32.3)	1.24 (0.71, 2.14)	1.30 (0.74, 2.30)
Cumulative exposure
Cumulative hormonal therapy exposureg
High (98–100%)	24 (25.5)	144 (31.4)	Ref	Ref
Intermediate (90–98%)	27 (28.7)	153 (33.4)	1.04 (0.57, 1.91)	1.02 (0.55, 1.90)
Low (0–90%)	43 (45.7)	161 (35.2)	1.60 (0.91, 2.81)	1.62 (0.91, 2.88)

Abbreviations: CI=confidence interval; Ref: referent group.

*P-trend <0.05.

^aCases: women with a breast cancer recurrence within 4 years of hormonal therapy initiation. Controls: women without a breast cancer recurrence at the time of a matched case's recurrence. Controls were randomly matched to cases in a ratio of 5 : 1, on tumour stage at diagnosis and age within a calliper of 5 years, using incidence density sampling without replacement.

^bAdjusted for tumour grade (low, intermediate, high and unspecified), progesterone receptor status (positive, negative and unspecified) and comorbidity score.

^cThe number of consecutive non-persistent days from the last day of hormonal therapy availability to the index date, stratified as persistent (<180 day gap) and non-persistent (⩾180 day gap).

^dAdjusted for hormonal therapy compliance.

^eThe proportion of days covered up to the first of either the date of non-persistence or the case/control index date, stratified by tertiles.

^fAdjusted for hormonal therapy persistence.

^gThe proportion of days covered up to the case/control index date.