First-Year Medical Student University of Pittsburgh
Rationale: In the 30% of epilepsy patients who are drug-resistant, randomized clinical trials have shown surgical resection to significantly improve seizure outcomes as opposed to continued antiepileptic drug therapy. Studies have shown that invasive monitoring, which is crucial for identifying the seizure focus and neighboring eloquent cortex in patients with drug-resistant epilepsy (DRE), and surgical treatment are often undervalued as effective interventions. Stereoelectroencephalography (SEEG) and subdural electrodes (SDE) are the most common invasive monitoring methods; however, the relative safety and efficacy of their use continues to be debated. As SEEG utilization increases in across the globe, it is important to understand how outcomes following invasive monitoring vary across countries and what regional factors contribute to these disparities. This is crucial given the differences in both surgeon experience and institutional variation in healthcare system structure. Methods: In a large cross-national database of patients undergoing invasive monitoring for epilepsy surgery, we sought to evaluate the association between social, economic, and educational indicators of the country of treatment and patient outcomes following invasive monitoring. We performed a mixed-effects analysis of an individual patient database of 595 subjects enrolled in 33 studies encompassing 25 neurosurgical centers in ten countries of invasive monitoring for epilepsy from 1996 to 2019. The dataset was structured hierarchically, with patients nested by their study country of origin. Explanatory variables were included for statistical analysis as either patient- or nation-level covariates, with patient-level consisting of clinical and procedural characteristics of individual patients and nation-level consisting of national social, economic, and educational indicators. Results: In the cohort of 595 patients undergoing invasive monitoring, twenty national socioeconomic indicators were studied. The average number of physicians per 100,000 population was 2.807 [range 1.710 (China) — 4.188 (Italy)], the median GDP growth was 2.012% annually [range -0.188% (Japan) — 10.702% (China)], and the average rate of unemployment was 6.568% of the total population [range 3.384% (Germany) — 10.387% (Italy)]. Upon preliminary univariable analysis, significant nation-level predictors of seizure outcome following either SEEG or SDE were hospital beds per 100,000 population, physician density, gross domestic product (GDP) growth, male and female educational attainment, and unemployment rate. On multivariable mixed-effects logistic regression, physician density (b=-0.5112, p< 0.00697) and GDP growth (b=0.53822, p< 0.00404) were the only nation-level covariates of significance associated with seizure outcome. A higher physician density was associated with lesser seizure freedom rates, while higher GDP growth was associated with greater seizure freedom rates. Conclusions: While patient-specific variables were the primary determinant of seizure outcomes, cross-national disparities also contribute to heterogeneity. Our findings highlight the importance of a systems-level dialogue to improve surgical outcomes for DRE patients. These results are important and consistent with literature examining system-level outcome discrepancies in other types of specialty care.9 However, interpretation of these findings suggest that in addition to patient-level covariates, there may be a large array of influencing factors associated with differences in rates of seizure freedom in DRE. Future work should examine causal mechanisms of these systems-level disparities to devise strategies for optimizing epilepsy surgery care. Funding: Please list any funding that was received in support of this abstract.: None.