Table 4.

Risk of atrial fibrillation among patients with Graves’ disease according to cumulative dose and treatment duration of anti-thyroid drug.

	n	AF	PYs	IR per 1,000 PYs	Model 1	Model 2	P for interaction
					Hazard ratio (95% CI)	Hazard ratio (95% CI)
Controls	470,300	5,209	3,299,357	1.58	Reference	Reference
Cumulative dose							< 0.01
Lowest	29,995	595	196,805	3.02	1.93 (1.77–2.09)	1.60 (1.47–1.74)
Middle	29,998	835	205,483	4.06	2.58 (2.39–2.77)	2.42 (2.25–2.61)
Highest	29,998	933	223,345	4.18	2.63 (2.45–2.82)	2.66 (2.48–2.86)
Treatment duration							< 0.01
Lowest	30,045	552	207,042	2.67	1.69 (1.55–1.84)	1.62 (1.48–1.77)
Middle	29,938	693	206,628	3.35	2.13 (1.96–2.30)	2.10 (1.94–2.27)
Highest	30,008	1,118	211,963	5.27	3.34 (3.13–3.56)	2.83 (2.65–3.02)

AF, atrial fibrillation; PYs, person-years; IR, incidence rate.

Cumulative doses were <5,743 mg (lowest), 5,743–22,055 mg (middle), and >22,055 mg (highest).

Treatment durations were <11.5 months (lowest tertile), 11.5–33.4 months (middle tertile), and >33.4 months (highest tertile).

Model 1: not adjusted.

Model 2: adjusted for household income and comorbidities