Table 3. Incidence and Relative Hazards of AF Among Participants Randomized to Vitamin D₃ vs Placebo.

End points	Vitamin D3 (n = 12 553)			Placebo (n = 12 566)			Vitamin D3 vs placebo
	No. of events	Total person-years	Events per 1000 person-years	No. of events	Total person-years	Events per 1000 person-years	Difference in events per 1000 person-years (95% CI)	Hazard ratio (95% CI)a	P value
Primary end point
All incident AF	469	65 046	7.2	431	65 137	6.6	0.6 (−0.3 to 1.5)	1.09 (0.96-1.25)	.19
Sensitivity analyses of primary end point
AF events excluding those with symptoms preceding randomization	438	64 948	6.7	404	65 046	6.2	0.5 (−0.3 to 1.4)	1.09 (0.95-1.25)	.22
AF events excluding those detected by CMS linkage data alone	373	64 727	5.8	361	64 919	5.6	0.2 (−0.6 to 1.0)	1.04 (0.90-1.20)	.60
AF events excluding atrial flutter alone and postoperative AFb	404	64 815	6.2	380	64 962	5.8	0.4 (−0.5 to 1.2)	1.07 (0.93-1.23)	.36
AF events excluding those confirmed by medical record aloneb	343	64 671	5.3	313	64 790	4.8	0.5 (−0.3 to 1.2)	1.10 (0.95-1.28)	.22
On-treatment analysisc	383	50 540	7.6	336	48 640	6.9	0.7 (−0.4 to 1.7)	1.09 (0.94-1.27)	.24
Secondary end points
Paroxysmal AF	267	65 046	4.1	259	65 137	4.0	0.1 (−0.6 to 0.8)	1.03 (0.87-1.23)	.71
Nonparoxysmal AF	188	65 046	2.9	158	65 137	2.4	0.5 (−0.1 to 1.0)	1.20 (0.97-1.48)	.10

Abbreviations: AF, atrial fibrillation; CMS, Centers for Medicare & Medicaid Services.

^aThe hazard ratio for each intervention was estimated in Cox models using indicators for treatment group, controlling for the second intervention, age, and sex.

^bPost hoc analyses.

^cAdherence-based analyses that censored follow-up data when a participant discontinued trial capsules or began taking more than 800 IU/d of nonstudy vitamin D₃.