ORLANDO — Sleep disorders in people with epilepsy are linked to a significantly higher risk for sudden unexplained death in epilepsy (SUDEP) and all-cause mortality, new research shows.
SUDEP is a major concern for epilepsy patients, study investigator Marion Lazaj, MSc, Center for Neuroscience Studies, Queen’s University, Kingston, Ontario, Canada, told Medscape Medical News, but she believes that SUDEP risk assessment is overly focused on seizure control.
"We want to push the idea that this mortality risk assessment needs to be widened to include sleep factors, and not just sleep disorders but even sleep disturbances," said Lazaj.
She also believes physicians should routinely discuss SUDEP with their patients with epilepsy. Given that the incidence of SUDEP is only about 1%, many clinicians don’t want to unduly frighten their patients, she added.
The findings were presented here at the American Epilepsy Society (AES) 2023 Annual Meeting.
The retrospective study included chart data from 1506 consecutive patients diagnosed with epilepsy at a single center over 4 years. The mean age of participants was about 37 years but there was a large age range, said Lazaj.
The cohort was divided into two groups. Group 1 included 1130 patients without a comorbid sleep disorder, and Group 2 had 376 patients with a primary comorbid sleep disorder, mostly obstructive sleep apnea (OSA) but also restless leg syndrome or insomnia.
They gathered demographic information including age, sex, employment status, education, and epilepsy-related data such as epilepsy type, duration, the number of anti-seizure medications and relevant information from hospital and emergency room (ER) records.
SUDEP Inventory
Researchers assessed SUDEP risk using the revised SUDEP-7 risk inventory. The first four items on this inventory focus on generalized tonic clonic seizure activity and occurrence while others assess the number of anti-seizure medicines, epilepsy duration, and the presence of other developmental delays.
Investigators then stratified patients into high risk (score on the SUDEP-7 of 5 or greater) and low mortality risk (score less than 5).
Results showed a significant association between a high mortality risk and having a comorbid sleep disorder (P = .033). Researchers also looked at all-cause mortality, including drownings and suicides, and found a similar significant association (P = .026). There was also an association between high risk and accidents and trauma (P = .042).
The researchers had access to overnight diagnostic polysomnography data for a smaller group of patients. Here, they found decreased sleep efficiency (P =.0098), increased spontaneous arousal index (P = .034), and prolonged sleep onset latency (P = .0000052) were all significantly associated with high SUDEP risk.
From the polysomnographic data, researchers found high SUDEP risk was significantly associated with a diagnosis of OSA (P = .034).
Powerful Study
Commenting on the findings for Medscape Medical News, Gordon F. Buchanan, MD, PhD, Beth L. Tross epilepsy associate professor, Department of Neurology, University of Iowa Carver College of Medicine, Iowa City, said he was "very excited" by the research.
"That this study attempts to look through data in a retrospective way and see if there’s additional risk with having comorbid sleep disorders is really interesting and I think really powerful," he said.
Sleep disorders "are potentially a really simple thing that we can screen for and test for," he added. He also noted that additional research is needed to replicate the findings.
Buchanan acknowledged that the SUDEP-7 inventory is not a particularly good tool and said there is a need for a better means of assessment that includes sleep disorders and other factors like sleep states and circadian rhythm, which he said affect SUDEP risk.
Lazaj and Buchanan report no relevant financial relationships.
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