Association Between Psychiatric Comorbidities and Mortality in Epilepsy

Abstract

Objective: To explore the impact of psychiatric comorbidities on all-cause mortality in adults with epilepsy from a cohort of patients admitted for video-EEG monitoring (VEM) over 2 decades.

Methods: A retrospective medical record audit was conducted on 2,709 adults admitted for VEM and diagnosed with epilepsy at 3 Victorian comprehensive epilepsy programs from 1995 to 2015. A total of 1,805 patients were identified in whom the record of a clinical evaluation by a neuropsychiatrist was available, excluding 27 patients who died of a malignant brain tumor known at the time of VEM admission. Epilepsy and lifetime psychiatric diagnoses were determined from consensus opinion of epileptologists and neuropsychiatrists involved in the care of each patient. Mortality and cause of death were determined by linkage to the Australian National Death Index and National Coronial Information System.

Results: Compared with the general population, mortality was higher in people with epilepsy (PWE) with a psychiatric illness (standardized mortality ratio [SMR] 3.6) and without a psychiatric illness (SMR 2.5). PWE with a psychiatric illness had greater mortality compared with PWE without (hazard ratio 1.41, 95% confidence interval 1.02-1.97) after adjusting for age and sex. No single psychiatric disorder by itself conferred increased mortality in PWE. The distribution of causes of death remained similar between PWE with psychiatric comorbidities and those without.

Conclusion: The presence of comorbid psychiatric disorders in adults with epilepsy is associated with increased mortality, highlighting the importance of identifying and treating psychiatric comorbidities in these patients.

Figure 1. Kaplan-Meier Plots of Survival Comparing PWE With and PWE Without Psychiatric Comorbidities

(A–F) The navy line represents the cumulative probability of death for people with epilepsy (PWE) with no psychiatric comorbidities admitted for video-EEG monitoring (VEM) over a period of 20 years. The maroon lines represent the cumulative probability of death in the groups of PWE with any psychiatric comorbidity, PWE with only depressive disorders, PWE with only anxiety disorders, PWE with only psychotic disorders, PWE with only substance misuse disorders, and PWE with only personality disorders admitted for VEM over a period of 20 years in parts A–F, respectively. Univariable Cox proportional hazards regression was used to compare the mortality between PWE with no psychiatric comorbidities and the respective group in each part. (A) In comparison to PWE with no psychiatric comorbidities, a significantly increased hazard ratio of mortality was observed in PWE with any psychiatric comorbidity (hazard ratio [HR] 1.41, 95% confidence interval [CI] 1.02–1.97). (B) In comparison to PWE with no psychiatric comorbidities, no significant difference was observed in the hazard ratio of mortality in PWE with comorbid depressive disorders only (HR 1.45, 95% CI 0.96–2.21). (C) In comparison to PWE with no psychiatric comorbidities, no significant difference was observed in the hazard ratio of mortality in PWE with comorbid anxiety disorders only (HR 0.77, 95% CI 0.24–2.47). (D) In comparison to PWE with no psychiatric comorbidities, no significant difference was observed in the hazard ratio of mortality in PWE with comorbid psychotic disorders only (HR 1.66, 95% CI 0.72–3.86). (E) In comparison with PWE with no psychiatric comorbidities, no significant difference was observed in the hazard ratio of mortality in PWE with comorbid substance misuse disorders only (HR 1.26, 95% CI 0.50–3.14). (F) In comparison with PWE with no psychiatric comorbidities, no significant difference was observed in the hazard ratio of mortality in PWE with comorbid personality disorders only (HR 1.35, 95% CI 0.58–3.16).