Patterns and preexisting risk factors of 30-day mortality after a primary discharge diagnosis of syncope or near syncope

Objectives: The risk of short-term mortality after an emergency department (ED) visit for syncope is poorly understood, resulting in prognostic uncertainty and frequent hospital admission. The authors determined patterns and risk factors for short-term mortality after a diagnosis of syncope or near syncope to aid in medical decision-making. Methods: A retrospective cohort study was performed of adult members of Kaiser Permanente Southern California seen at 11 EDs from 2002 to 2006 with a primary discharge diagnosis of syncope or near syncope (International Classification of Diseases, Ninth Revision [ICD-9] 780.2). The outcome was 30-day mortality. Proportional hazards time-to-event regression models were used to identify risk factors. Results: There were 22,189 participants with 23,951 ED visits, resulting in 307 deaths by 30 days. A relatively lower risk of death was reached within 2 weeks for ages 18 to 59 years, but not until 3 months or more for ages 60 and older. Preexisting comorbidities associated with increased mortality included heart failure (hazard ratio [HR] = 14.3 in ages 18 to 59 years, HR = 3.09 in ages 60 to 79 years, HR = 2.34 in ages 80 years plus; all p < 0.001), diabetes (HR = 1.49, p = 0.002), seizure (HR = 1.65, p = 0.016), and dementia (HR = 1.41, p = 0.034). If the index visit followed one or more visits for syncope in the previous 30 days, it was associated with increased mortality (HR = 1.86, p = 0.024). Absolute risk of death at 30 days was under 0.2% in those under 60 years without heart failure and more than 2.5% across all ages in those with heart failure. Conclusions: The low risk of death after an ED visit for syncope or near syncope in patients younger than 60 years old without heart failure may be helpful when deciding who to admit for inpatient evaluation. The presence of one or more comorbidities that predict death and a prior visit for syncope should be considered in clinical decisions and risk stratification tools for patients with syncope. Close clinical follow-up seems advisable in patients 60 years and older due to a prolonged risk of death.