Compared with the general population, patients with newly diagnosed symptomatic epilepsy have reduced life expectancy, according to an investigation published in the November 2017 issue of Epilepsia. Patients with newly diagnosed idiopathic or cryptogenic epilepsy, however, have a normal or prolonged life expectancy. The year of diagnosis and the type of epilepsy appear to influence life expectancy.
Previous Estimates Had Weaknesses
Many studies have suggested increased mortality among patients with epilepsy. Two previous investigations have reported the more specific measure of life expectancy in epilepsy, but both had methodologic weaknesses and were prone to substantial bias, said Claudia A. Granbichler, MD, PhD, a neurology resident in Tel-Aviv.
Dr. Granbichler and colleagues examined data for all patients visiting the epilepsy outpatient clinic of Innsbruck Medical University in Austria to calculate their life expectancy. They included 1,112 adults who presented between January 1, 1970, and December 31, 2010, in their analysis. Patient data were recorded and updated continuously over time. Dr. Granbichler and colleagues compared patients’ life expectancies at the year of diagnosis and at five, 10, 15, and 20 years following diagnosis to those of the general population.
The authors classified patients’ epilepsies as symptomatic, idiopathic, or cryptogenic. They defined symptomatic epilepsy as the result of a known or suspected CNS disorder. Epilepsies not preceded by another disorder were considered idiopathic. The authors defined epilepsies of unknown cause as cryptogenic.
Life Expectancy Improved With Time
The difference in life expectancy between patients with epilepsy and the general population depended on the type of epilepsy and the time of diagnosis. Between 1970 and 1980, patients diagnosed with symptomatic epilepsy had a substantially greater reduction in life expectancy (–7.4 years in women and –7.2 years in men) than people diagnosed with idiopathic epilepsy (–5.5 years in women and –5.2 years in men) and people diagnosed with cryptogenic epilepsy (–1.8 years in women and –1.4 years in men).
Regardless of the type of epilepsy, patients diagnosed in subsequent decades had progressively smaller reductions in life expectancy, relative to the general population, or prolonged life expectancy. For all three groups, life expectancy increased with increasing duration of epilepsy.
Participants diagnosed with cryptogenic epilepsy between 2001 and 2010 had increased life expectancy, compared with the general population (2.5 years in women and 3.4 years in men). This increased life expectancy could be explained by lower mortality resulting from decreased engagement in risky activities such as driving motorcycles, skiing, and mountain climbing, said Dr. Granbichler. People with epilepsy also may benefit from more frequent medical follow-ups and laboratory testing.
A potential limitation of the study is that patients had different follow-up durations because of their varying dates of entry and the investigation’s fixed end date. The comparatively short follow-up duration may have introduced positive bias into the estimates of life expectancy for patients diagnosed after 2000, said Dr. Granbichler.
Granbichler CA, Zimmermann G, Oberaigner W, et al. Potential years lost and life expectancy in adults with newly diagnosed epilepsy. Epilepsia. 2017;58(11):1939-1945.