Predictors of Mortality in Older Adults With Epilepsy: Implications for Learning Health Systems.

Abstract

To determine the incidence of epilepsy and subsequent 5-year mortality among older adults, as well as characteristics associated with mortality. This was a retrospective cohort study of Medicare beneficiaries age 65 or above with at least 2 years enrollment before January 2009. Incident epilepsy cases were identified in 2009 using ICD-9-CM code-based algorithms; death was assessed through 2014. Cox regression models examined the association between 5-year mortality and incident epilepsy, and whether mortality differed by sociodemographic characteristics or comorbid disorders. Among the 99,990 of 33,615,037 beneficiaries who developed epilepsy, most were White (79.7%), female (57.3%), urban (80.5%), and without Medicaid (71.3%). The 5-year mortality rate for incident epilepsy was 62.8% (62,838 deaths). In multivariable models, lower mortality was associated with female sex (adjusted hazards ratio [AHR] 0.85, 95% confidence interval [CI] 0.84-0.87), Asian race (AHR 0.82, 95% CI 0.76-0.88), and Hispanic ethnicity (AHR 0.81, 95% CI 0.76-0.84). Hazard of death increased with comorbid disease burden (per 1-point increase: AHR 1.27, 95% CI 1.26-1.27) and Medicaid coinsurance (AHR 1.17, 95% CI 1.14-1.19). Incident epilepsy was particularly associated with higher mortality when diagnosed after another neurologic condition: Parkinson disease (AHR 1.29, 95% CI 1.21-1.38), multiple sclerosis (AHR 2.13, 95% CI 1.79-2.59), dementia (AHR 1.33, 95% CI 1.31-1.36), traumatic brain injury (AHR 1.55, 95% CI 1.45-1.66), and stroke/TIA (AHR 1.20, 95% CI 1.18-1.21). Newly diagnosed epilepsy is associated with high 5-year mortality among Medicare beneficiaries. Future studies that parse the interplay of effects from underlying disease, race, sex, and poverty on mortality will be critical in the design of learning health care systems to reduce premature deaths.