Table 3.

Risk factors for death by 30 days subsequent to any ED visit for syncope during the study period (proportional hazards model).

Characteristics	Death by 30 days
	HR	(95% CI)	P-value
Male	1.36^ˆ	1.08-1.72	0.009
Age^*
60-79 years	6.59^ˆ	3.83-11.34	<0.001
80 plus years	11.73^ˆ	6.58-20.92	<0.001
Recent visit for syncope^†	1.86^ˆ	1.08-3.18	0.024
Diabetes	1.49^ˆ	1.16-1.90	0.002
Hypertension	0.79	0.57-1.10	0.161
Dysrhythmia	1.14	0.88-1.48	0.318
Valvular heart disease	1.16	0.86-1.56	0.332
Myocardial infarction	1.16	0.83-1.62	0.380
Cerebrovascular disease	0.92	0.66-1.28	0.622
Seizure	1.65^ˆ	1.10-2.48	0.016
Dementia	1.41^ˆ	1.03-1.94	0.034
Gastrointestinal hemorrhage	0.88	0.52-1.51	0.652
Heart failure^‡
18-59 years	14.3^ˆ	6.28-32.5	<0.001
60-79 years	3.09^ˆ	2.12-4.49	<0.001
80 plus years	2.34^ˆ	1.63-3.36	<0.001

Reference group: age 18-59 years.

^†

Defined as one or more visits within the 30 days of the index ED visit.

^‡

HR for presence vs. absence of the comorbidity within the same age group.

^ˆ

Significant associations (P<0.05).

Multivariable Cox proportional hazards model using all ED visits for syncope during the study period. Multiple visits by a participant were clustered for correction of standard errors using the robust, sandwich estimator. ED visits among 415 patients during the first month of the study (Jan 2002) were dropped from analysis so that all patients included in the regression model had at least one month of observation to determine a history of prior syncope visits within 30 days of the index ED visit. Among the 21,774 patients included in the model, there were 23,491 visits, 103 deaths at 7 days, and 307 deaths at 30 days.

Comorbidity definitions are provided in the Data Supplement.