Comorbid and underlying diseases--major determinants of excess mortality in epilepsy

The reasons why the mortality of patients with epilepsy is significantly increased, even many years after seizure onset, are not fully understood. The aim of this study was to compare the distribution of the causes of death (COD) in an epilepsy population with that in the general population and with previous findings in other epilepsy populations. In addition, we investigated the chronological relationship between the onset of epilepsy and the onset of the diseases leading to death.

The COD for patients who were registered with a diagnosis of epilepsy at Stavanger University Hospital from August 1 1995-July 31 2005 and died during the same period were obtained from the Norwegian Cause of Death Registry and the hospital records were reviewed. The distribution of the corresponding COD in the general population was obtained from Statistics Norway.

At least 6.8% (18/266) of the deaths of epilepsy patients were directly related to seizures. Epilepsy patients who had died from brain tumors (n=46) were excluded from further analysis. Of the remaining 220 deceased epilepsy patients, 39 (17.7%) had died from heart disease, compared with 27.8% in the general population (p<0.001). No other significant differences in the distribution of COD in the epilepsy population and the general population were identified. The majority of the epilepsy patients who died from heart disease (71.8%) and cerebrovascular disease (72%) had cardiovascular disease prior to seizure onset and in at least 43% of those who died from neoplasms the onset of malignancy occurred before the first seizure.

Comorbid diseases and underlying conditions were the major determinants of mortality in this population of epilepsy patients. Conditions that are not caused by epilepsy or its treatment may represent an important explanation for the previously documented excess mortality in people with epilepsy.