Abstracts

Rationale: To investigate whether insurance status is associated with the receipt of presurgical evaluations and epilepsy surgery in the United States.Methods: We performed a retrospective study using data from the National Inpatient Sample (NIS) database between 1998 and 2008. The NIS database is an administrative data for all hospital discharges from a weighted sample of approximately 20% of all hospitals in the United States. Our study population includes hospital discharges of patients with a diagnostic code related to epilepsy or convulsions (ICD-9-CM, 345.xx, 780.3, or 780.39), representing approximately 2.78 million discharges from 1998 to 2008. The primary outcome of interest was brain lobectomy (ICD-9-CM procedure code 01.53). The main independent variable of interest was primary payer (private insurance versus public insurance such as Medicaid and Medicare). In addition, utilization of pre-surgical evaluation procedures including video/EEG telemetry (ICD-9-CM code 89.19), Wada test (ICD-9-CM code 89.10), and intracranial EEG monitoring (ICD-9-CM code 02.93) were analyzed by payer type. Multiple logistic regressions were used to estimate odds ratios and to adjust for other covariates such as age, gender, race, and income. Differences across groups among categorical and continuous variables were tested using Chi-square test and t-test, respectively. Temporal trends in epilepsy surgery by payer type were analyzed to test for change over time. All our analyses incorporated survey weights to account for the sampling design.Results: There were 5,902 discharges of epilepsy-related lobectomy. There were significant differences based on age, race, gender, median household income, and primary payer between the surgery and the non-surgery group. Interestingly, over one-half of the epilepsy population in the dataset is on public insurance, yet less than one-third of surgeries were performed on these patients. Compared to public health insurance, private insurance status was associated with higher likelihood to receive epilepsy surgery (OR 2.15; 95% CI 1.62-2.86), undergo video-EEG telemetry (OR 1.64; 95%CI 1.47-1.84), receive a Wada test (OR 1.75; 95% CI 1.12-2.75), and intracranial EEG monitoring (OR 1.77; 95% CI 1.44-2.11). In contrast, African-American race (OR 0.22; 95%PI 0.13-0.37) and age 65 (OR 0.01, 95%CI 0.00-0.07) were associated with lower likelihood of receiving epilepsy surgery. Analysis of temporal trends among persons receiving lobectomy surgery did not show significant change in payer type over time.Conclusions: Our analysis clearly demonstrates disparities on presurgical evaluations and epilepsy surgery among patients who enroll in Medicaid or Medicare program compared to those who have private insurance plan. These findings are significant because over half of the population with epilepsy is on public insurance, yet this group has less access to a highly effective treatment for intractable epilepsy.