Monday July 22 2013
Epilepsy is a condition that affects the brain, causing seizures
"People with epilepsy 11 times more likely to die prematurely, study finds," is the news in The Daily Telegraph. The story comes from a large long-term study of records of people with epilepsy. The study compared them with their unaffected siblings and the general population.
Of the people with epilepsy, 8.8% died prematurely, compared with just 0.7% in others. After taking social and demographic factors into account, the researchers estimated that people with epilepsy were 11 times more likely to die prematurely compared with people who did not have epilepsy.
This increased risk appeared to be across all causes of death, though the second most common cause of death after cancer was from neurological causes. This suggests that the underlying disease causing the person's epilepsy could be related to the increased risk.
Mental health conditions also had an impact on premature death rates. People with epilepsy had three times the odds of suicide compared with controls. Rates of death from "external" causes, such as accidents, were also significantly higher.
It's clear from this study that people with epilepsy need their condition to be identified, monitored and treated, with particular attention paid to their mental wellbeing.
Where did the story come from?
The study was carried out by researchers from the University of Oxford and the Karolinska Institutet, Stockholm, and was funded by the Wellcome Trust, the Swedish Prison and Probation Service, and the Swedish Research Council.
It was published in the peer-reviewed medical journal, The Lancet.
The Daily Telegraph coverage of the study is accurate and informative, containing some additional useful advice from the deputy chief executive of the epilepsy charity Epilepsy Action: "Getting the best possible support and treatment is important to help to reduce the likelihood of people with epilepsy experiencing mental illness".
What kind of research was this?
The researchers estimate that epilepsy accounts for 0.7% of the disease burden worldwide and is associated with a substantial premature mortality. Almost half of the deaths associated with epilepsy are among people aged under 55. Around 16% of all epilepsy-related deaths are caused by accidents (vehicle or otherwise) and 5% of deaths are estimated to be from suicide.
This prospective cohort study used national population data to follow almost 70,000 people with epilepsy for 40 years. This was to examine the prevalence of premature death among people with epilepsy and look into what factors are associated with these deaths.
What did the research involve?
The researchers linked several nationwide population registers in Sweden:
- the national patient register
- the national censuses from 1970 and 1990
- the multigeneration register (which connects all Swedish residents to their parents)
- the cause of death register
The study population included more than seven million people born between 1954 and 2009. The patient registers started in 1969, so their follow-up covered the 40 years from 1969 to 2009 (children who were born and died between 1954 and 1969 were excluded).
The researchers identified people with epilepsy using the national patient register, which has recorded people hospitalised with epilepsy in Sweden since 1969, and since 2001 has recorded people having outpatient appointments with specialists. Epilepsy diagnosis was made according to the International Classification of Diseases (ICD) codes.
The cause of death register, which is based on death certificates, was used to identify all deaths and causes of death between 1969 and 2009.
The researchers also gathered data on confounding factors that could be associated with premature death.
- measures of disposable income
- marital status
- immigrant status
- inpatient or outpatient diagnosis of any mental health condition
- history of alcohol abuse
- history of substance use
For each person with epilepsy, up to 10 controls without epilepsy from the general population were matched by birth year and gender. The researchers also analysed data on the people against that from unaffected siblings. The researchers then looked at the association between epilepsy diagnosis and cause of death, taking into account the confounders listed above.
What were the basic results?
The researchers identified 69,995 individuals with epilepsy and compared them with 660,869 age- and gender-matched controls. Though the entire length of follow-up of the study was 40 years, most individuals in the study were followed for an average of nine years each.
During the course of follow-up, 8.8% of the people with epilepsy died (6,155) compared with 0.7% of controls (4,892). With adjustment for sociodemographic factors, people with epilepsy were 11 times more likely to die from any cause than people without epilepsy (odds ratio (OR) 11.1, 95% confidence interval (CI) 10.6 to 11.6).
When looking at cause of death, people with epilepsy had a significantly increased risk of death from all causes.
The most common cause of death among people with epilepsy was cancer (23% of deaths), followed by diseases of the brain or nervous system (21% of deaths) and "external" causes (16% of deaths), including accidents and suicides.
People with epilepsy had three times the risk of suicide (OR 3.7, 95% CI 3.3 to 4.2) and five times the risk of "non-vehicle accidents" (OR 5.5, 95% CI 4.7 to 6.5), which included accidental falls, poisoning or drowning.
Among controls, the most common cause of death was in fact external causes (43% of control deaths), followed by cancer (23%) and cardiovascular diseases (13% of control deaths). While this may seem unusual, accidental deaths and suicides are a leading cause of death in younger adults.
Similar results were obtained when people with epilepsy were compared with their unaffected siblings. This showed that the results were not being influenced by genetic factors and upbringing.
Overall, 41% of people with epilepsy had a lifetime diagnosis of a mental health condition – 18% of sufferers had a mental health diagnosis before their epilepsy was diagnosed and 23% had a mental health diagnosis after their epilepsy diagnosis. This compared with 10% of controls having any lifetime diagnosis of a mental health condition.
When the researchers looked at the risk of death from an external cause, mental health diagnosis appeared to have greater influence on risk than epilepsy.
For example, compared with someone without epilepsy and without a mental health diagnosis:
- someone with epilepsy but without a mental health diagnosis had twice the risk of death from an external cause (OR 2.3, 95% CI 1.9 to 2.8)
- someone without epilepsy but with a mental health diagnosis had almost six times the risk of death from an external cause (OR 5.8, 95% CI 5.2 to 6.6)
- someone with epilepsy and with a mental health diagnosis had more than 10 times the risk of death from an external cause (OR 10.6, 95% CI 9.2 to 12.2)
Looking specifically at diagnosis of depression or substance use disorder, the risk figures for death from external causes were higher, but with the same pattern of risk as above.
How did the researchers interpret the results?
The researchers conclude that, "Reducing premature mortality from external causes of death should be a priority in epilepsy management. Psychiatric comorbidity plays an important part in the premature mortality seen in epilepsy. The ability of health services and public health measures to prevent such deaths requires review."
This is a valuable review that uses reliable Swedish national data sources to examine the causes of premature death for almost 70,000 people with epilepsy.
The results clearly suggest that premature death is more likely among people with epilepsy compared with people in the general population who do not have epilepsy. This increased risk appears to be across all causes of death. The second most common cause of death after cancer was from neurological causes. This could therefore be associated with the underlying disease process responsible for the person's epilepsy.
However, the study also highlights the contribution of mental health diagnoses (diagnosed in 41% of people with epilepsy) to the increased risk of early death, particularly when it comes to deaths from external causes, such as accidents. People with epilepsy also had three times the odds of suicide.
This research was conducted in Sweden, and it would be useful to see statistics from the UK to see if this country follows a similar pattern. Also, as the researchers say, there are limitations related to how health conditions are recorded (called "coding"), which means that there may not be fully reliable data on the subtypes of epilepsy. Similarly, there may also have been people with epilepsy who were missed altogether, having never presented to hospital services.
The study also didn't look at whether people were receiving treatment for epilepsy or mental illness, and what impact this may have on reducing the risk of premature death. It could be the case that many people who respond well to epilepsy treatment (most commonly anti-epileptic drugs) do not have an increased risk of premature death.
Nevertheless, the researchers' conclusion is apt: "The importance of identifying, monitoring, and treating [mental health illness in people with epilepsy] is underscored by these results."
If you are living with epilepsy and feel that the condition is adversely affecting your mental health, you should discuss your concerns with the doctor in charge of your care.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.