Article In Brief
Lower socioeconomic status was associated with higher rates of sudden death due to epilepsy, reflecting disparities in care that deserve attention, experts say.
Epilepsy patients in the poorest communities are more than twice as likely to suffer sudden unexplained death due to epilepsy (SUDEP) than their counterparts at the highest end of the socioeconomic ladder, although the reasons for this are difficult to ascertain, according to a review of medico-legal claims and medical examiners' office records in three geographically diverse areas across the United States.
A team of researchers led by Daniel Friedman, MD, an associate clinical professor of neurology at NYU Langone School of Medicine's Epilepsy Center, studied all medico-legal investigations for SUDEP at medical examiner (ME) offices in New York City, Maryland, San Diego County, in 2009 and 2010, and again between 2014 and 2015.
The investigators found 159 SUDEP cases in neighborhoods with the lowest socioeconomic status compared with 43 cases in the highest income brackets. The ratio between the lowest and highest socioeconomic status quartiles was 2.6 in 2009 and 2010, and 3.3 in 2014 and 2015. And although overall cases fell by 36 percent between the two study periods, the disparity between groups remained similar over the full five-year study period, the researchers reported in the April 23 online edition of Neurology.
Epilepsy Status by Zip Codes
The researchers identified all decedents for whom epilepsy/seizure was listed on death certificates as a cause/contributor to death, or as a comorbid condition, as well as coding reports and data pertaining to overall socioeconomic status (SES) in each area by ZIP code. The team also utilized data from the Centers for Disease Control and Prevention and the U.S. Census Bureau.
“We found that community socioeconomic status has a significant impact on SUDEP rates,” Dr. Friedman told Neurology Today. “Further studies are needed to understand the causes of disparities in poorer communities in order to identify potential targets for intervention.”
Several possible factors can influence seizure control, he said, including the inability to afford or obtain seizure control drugs, poorer adherence to drug regimens, and limited access to specialty care for treatment-resistant seizures. Mental illness and substance abuse can also interfere with the ability of individuals to self-manage their epilepsy.
Yet, even when the data was adjusted for these factors, the researchers did not find age, adherence to anti-seizure medications, substance abuse history, or comorbidity between the lowest and highest income areas that might explain the SUDEP disparities, especially to the degree that the calculations indicated.
Unfortunately, the team was unable to determine disability status, seizure frequency, or seizure severity for a majority of the cases, Dr. Friedman said. ME reports and death certificates likely underestimate the true number of SUDEP cases, he added.
“Because SUDEP rates were calculated on the basis of ME investigation and coding of death certificates, we very likely did not ascertain all SUDEPs. Moreover, the observed overall SUDEP rate of 0.33 to 0.66 per 1,000 patient-years was lower than the rate by patient-years reported in earlier population-based studies that have examined medical and vital records,” Dr. Friedman noted.
Limitations, More Questions
It is difficult to ascertain the exact scope of SUDEP for a number of reasons, not the least of which is a lack of specific mention of epilepsy or seizure on death certificates, Dr. Friedman told Neurology Today.
“MEs and coroners may underrecognize epilepsy as a cause of sudden expected death, and/or may not view epilepsy as having been significantly associated with a death,” he noted. “Also, some may not obtain a history of seizures or epilepsy due to insufficient access to medical history of the decedent.”
For example, the review of all 2014 and 2015 San Diego County cases involving patients with a known history of seizure/epilepsy but where seizure/epilepsy was not mentioned on the death certificate, none were determined to be SUDEP.
In another example, they prospectively analyzed all 2016 ME cases in Maryland with a history of seizure or epilepsy, and found 28 definite/probable SUDEP cases, but in 17.9 percent, neither seizure nor epilepsy was mentioned on the death certificate.
A national study from Sweden, published in Neurology in 2017, indicated that epilepsy was not mentioned on the death certificates for almost 40 percent of SUDEP cases, Dr. Friedman said.
“Taking all of this into account, there may be more missing cases in certain areas that affected our results. Also, our estimate of the prevalent epilepsy population is extrapolated from CDC telephone surveys and US Census data. And while we adjusted for factors associated with epilepsy prevalence such as region, age, and household income, the inherent imprecision in these estimates could have affected our results,” he explained.
In addition, because the records that were reviewed were those used for medico-legal investigation, information was not readily available about certain key SES factors that can limit access to care, such as insurance status, and this may have influenced the results.
He noted that all three ME offices were in states that opted to receive federal funds to expand Medicaid eligibility under the Affordable Care Act in 2014.
“However, despite possible improved access under expanded Medicaid, the disparities in SUDEP rates between the poorest and wealthiest persisted, suggesting that other factors besides insurance and access influence community socioeconomic status on epilepsy mortality.”
Camilo Gutierrez, MD, an associate professor of neurology at the University of Maryland School of Medicine, called the study, “a robust analysis that works to account for many limitations and reveals a clear disparity in SUDEP rates by socioeconomic status.”
He noted that even though severity of epilepsy could not be accounted for by the research team, nor other variables that might impact incidence, the data point to inherent difficulties in studying SUDEP as well as bridging the socioeconomic status gap among patients.
“This is especially true when it is increasingly clear that access to medical care is likely not driving this difference,” he told Neurology Today. “We need to look at other factors. This study mentions increased physician awareness to SUDEP and educational efforts as a potential reason for decreased SUDEP. It is critical to educate all providers about cultural competency and [other] social determinants of health,” he said.
To increase awareness of strategies to decrease the influence of socioeconomic disparities, Dr. Gutierrez said all clinicians must continue to educate themselves about SUDEP and be aware of just how much disparities in socioeconomic risk can influence patient risk.
“Above all, providers can learn to appreciate that health disparities are not just a social issue. Clinicians have the capacity and responsibility to create change by personally working to mitigate physician bias and improving their cultural competency in the community they serve.”
Barbara Jobst, MD, PhD, FAAN, professor of neurology at Dartmouth University and director of the Dartmouth-Hitchcock Epilepsy Center in Lebanon, NH, also applauded the investigators.
“This is a very important paper,” she told Neurology Today. “The study was very well conducted, included a large sample size, and corrected for possible bias with statistical modeling. Also, efforts for case ascertainment were conducted in a reliable and comprehensive manner.”
While the study clearly demonstrated disparities between higher and lower income areas, reasons for this remain speculative,” she said, but could include access to specialized care in epilepsy centers, access to anti-seizure medications, or disparities in patient supervision.
“Regardless the reasons, the study clearly demonstrates that disparities in epilepsy care are prominent and deserve attention,” Dr. Jobst said.
She also noted that the study authors reported that the overall SUDEP rate declined from 2010 to 2015. “This could be a result of educational efforts aimed at patients and providers, even though, as the authors discussed, it might potentially reflect improved access to care through the Affordable Care Act and Medicaid expansion. Access to care remains a factor that does not only affect overall health, but this study shows it also affects mortality in epilepsy patients.”
Jerzy P. Szaflarski, MD, PhD, professor and director of the University of Alabama Epilepsy Center, in Birmingham, agreed that many possible contributors to the observed disparities can be difficult to quantify.
“One of the biggest drivers of SUDEP is lack of seizure control,” he said. “As the authors emphasized in the introduction to the report, the SUDEP rate in newly-diagnosed patients with epilepsy is many-fold lower than in those who have chronic, poorly controlled, and treatment-resistant epilepsy.”
To increase awareness of strategies to address the problem, he told Neurology Today that two main strategies can be employed—the first is educating patients on the dangers of having uncontrolled seizures/epilepsy and reminding providers about the need to control all seizures.
“The second is to aggressively treat all patients with uncontrolled seizures by adjusting their medications, referring them to physicians who specialize in epilepsy care, and for epilepsy surgery evaluation,” Dr. Szaflarski said. “Freedom from all seizures should be the ultimate goal for patients and providers. However, even modest improvements in seizure control have been shown to reduce SUDEP rates,” he said, citing a 2011 study in Lancet Neurology.