Table 2. Cox proportional hazard ratio with 95% CI of incident hospitalized HF events by quartiles of baseline RMSSD, SDNN and rHR.

Quartiles	All HF subtypes (n = 28,603)
	n	Person-years	Rate per 1000 person-years (95% CI)	Model 1 HR (95% CI)	Model 2 HR (95% CI)	Model 3 HR (95% CI)
RMSSD (ms)
Q1 (1.24–10.51)	612	104,894	5.83 (5.38–6.31)	1.27 (1.13–1.44)*	1.17 (1.02–1.33)*	1.17 (1.02–1.33)*
Q2	511	108,109	4.72 (4.33–5.15)	1.09 (0.96–1.24)	1.04 (0.91–1.20)	1.04 (0.91–1.19)
Q3	534	115,874	4.61 (4.23–5.01)	0.95 (0.83–1.08)	0.95 (0.82–1.10)	0.95 (0.83–1.10)
Q4 (ref) (25.61–361.23)	365	120,365		1	1	1
P-trend			3.03 (2.73–3.35)	<0.001	0.034	0.037
SDNN (ms)
Q1 (0.91–10.19)	649	105,052	6.17 (5.71–6.66)	1.39 (1.22–1.57)*	1.23 (1.08–1.40)*	1.22 (1.07–1.39)*
Q2	494	109,599	4.51 (4.12–4.92)	1.10 (0.97–1.25)	1.04 (0.91–1.20)	1.04 (0.91–1.19)
Q3	442	115,940	3.81 (3.47–4.18)	0.99 (0.87–1.13)	0.96 (0.83–1.10)	0.95 (0.82–1.09)
Q4 (ref) (24.17 –	437	118,651	3.68 (3.35–4.04)	1	1	1
313.20)				<0.001	0.004	0.005
P-trend
rHR (bpm)
Q1 (Ref) (33–59)	454	116,582	3.89 (3.54–4.26)	1	1	1
Q2	424	108,439	3.91 (3.55–4.29)	1.03 (0.90–1.17)	1.02 (0.89–1.18)	1.02 (0.89–1.18)
Q3	510	113,278	4.50 (4.12–4.91)	1.17 (1.03–1.33)*	1.08 (0.94–1.24)	1.08 (0.94–1.24)
Q4 (73–123)	634	110,943	5.71 (5.28–6.17)	1.61 (1.42–1.81)*	1.32 (1.15–1.50)*	1.31 (1.15–1.50)*
P-trend
				<0.001	<0.001	<0.001

Model 1: adjusted for age and race

Model 2: Model 1 + adjusted for smoking status, alcohol, education, physical activity, BMI, hyperlipidemia, hypertension, diabetes mellitus, LVH, beta-blocker use, calcium channel blocker use, hormone therapy use

Model 3: model 2 + adjusted for time-varying incident CHD

HF: heart failure; ms: millisecond; SDNN: standard deviation of normal-to-normal RR interval; RMSSD: root mean square of successive difference of RR intervals; rHR: resting heart rate

*p < 0.05