Table 2. Hazard ratios for heart diseases in breast cancer patients compared to the matched cohort.

		Arrhythmia		Heart failure		Ischemic heart disease
	No.	HR (95% CI)	No.	HR (95% CI)	No.	HR (95% CI)
Time since diagnosis
<1 year	64	2.14 (1.63–2.81)	22	2.71 (1.70–4.33)	38	1.45 (1.03–2.04)
1–2 years	34	1.08 (0.76–1.53)	19	2.07 (1.27–3.37)	34	1.12 (0.79–1.61)
2–5 years	107	1.07 (0.88–1.30)	38	1.14 (0.82–1.59)	72	0.84 (0.66–1.07)
5–10 years	204	1.13 (0.98–1.30)	78	1.02 (0.81–1.29)	104	0.82 (0.67–1.00)
10–17 years	161	1.42 (1.21–1.67)	86	1.28 (1.03–1.59)	59	0.79 (0.61–1.03)

Abbreviations: No. = number of cases. HR = hazard ratio. CI = confidence interval. The HRs are estimated using flexible parametric model and conditioned on matching criteria (year of birth). In all models, time since index date was the underlying time scale and a restricted cubic spline with four internal and two boundary knots (five degrees of freedom) placed at quintiles of the event times was used for the baseline hazard. All analyses were stratified by time since index date. Statistically significant results with p-value<0.05 are bolded.