Table 3. Hazard ratio for mortality within three weeks after admission using Cox-regression.

	Cox regression				Cox regression
	Unadjusted	Model 1	Model 2		Unadjusted	Model 1	Model 2
SDNN				RMSSD
≤8	reference	reference	reference	≤8	reference	reference	reference
>8	0.70 (0.41–1.19)	0.53 (0.31–0.92)	0.55 (0.32–0.95)	>8	0.99 (0.59–1.67)	0.63 (0.36–1.11)	0.61 (0.35–1.07)

Model 1 adjusted for age.

Model 2 adjusted for age and chronic heart disease.

Note: SDNN = standard deviation of normal to normal heartbeat intervals; RMSSD = root mean square of successive differences between adjacent heartbeats. Both SDNN and RMSSD cut-offs are in msec.