Verbal autopsy and SUDEP
[Part 1: Facts; Lathers CM & Schraeder PL]
Sudden unexpected death in epilepsy (SUDEP) refers to the sudden death of an individual with a clinical history of epilepsy, in whom a post-mortem examination fails to uncover a gross anatomic, toxicological, or environmental cause of death (Shields et al., 2002). Lathers et al. (2015) propose a new Risk Factor Cluster and Identification Method and Classification to demystify SUDEP. Classifying such deaths is made difficult in the absence of a post-mortem. However, research suggests that SUDEP is under-reported even when a post-mortem is available. In the US, Schraeder et al. (2006, 2009, 2011) concluded that the incidence for SUDEP most likely is not accurately reflected in any data utilizing death certificate diagnoses. The incidence of SUDEP is probably higher than assumed since many SUDEP deaths are missed (Lathers & Schraeder, 2009).
Data for third world countries is even more limited than that in Europe and North America, and commonly does not utilize post-mortem examinations (Lathers & Schraeder, 2009). In general, developing countries do not have a complete civil registration system in place to collect and provide data regarding public health issues (Hill et al., 2007). SUDEP under-reporting has been noted in Nigeria, where most deaths in individuals with epilepsy occur at home (Sanyo, 2005). Autopsies are not usually conducted to determine the cause of death and deaths may never be reported.
To improve understanding of SUDEP deaths and to glean information about the circumstances of the ‘sudden death event’ in epilepsy, the verbal autopsy may be used. The methodology emphasizes the importance of talking with members of the family and/or close friends of the patient who has died unexpectedly. Discussions must include facts about the longitudinal history of epilepsy in the deceased, especially including information about the clinical events at the time of a witnessed death. Verbal autopsies are used to determine likely cause of death for individuals with no direct clinical observation regarding the terminal event (Snow et al., 1993). In such situations, the interview conducted during the verbal autopsy seeks key symptoms and signs cited by the relatives and friends of the deceased. Final diagnosis of cause of death is assigned according to the symptom complexes. The technique of verbal autopsy makes the assumption that individual disease entities have discrete symptom complexes that can be easily and accurately recognized and remembered. However, in assessing responses it is necessary to consider the influence of the setting on the responses (Snow et al., 1993). When it comes to classifying the cause of death using data provided by the verbal autopsy, physician review may not be available in developing countries. Quigley et al. (1999) compared the diagnostic accuracy of physician review, expert algorithms, and data-derived algorithms in adult verbal autopsies conducted in hospitals in Tanzania, Ethiopia, and Ghana, concluding that where physician review is not feasible, expert and data-derived algorithms provide an alternative approach for assigning many causes of death. However, verbal autopsy methods need to be standardized and validated to generate accurate global estimates to determine policy and resource allocation in developing countries.
In rural Kenya, Ngugi et al. (2014) estimated premature mortality and identified causes of death and associated factors in people with active convulsive epilepsy (ACE). People with ACE were identified in a cross-sectional survey and followed up regularly for 3 years. A validated verbal autopsy tool was used to establish putative causes of death. There were 61 deaths among 754 people with ACE, yielding a rate of 33.3/1,000 persons/year. Overall standardized mortality ratio was 6.5. Mortality was higher across all ACE age groups. Nonadherence to antiepileptic drugs (adjusted rate ratio [aRR] 3.37), cognitive impairment (aRR 4.55), and age (50+ years) (rate ratio 4.56) were risk factors for premature mortality. Most deaths (56%) were directly related to epilepsy, with prolonged seizures/possible status epilepticus (38%) most frequently associated with death; some of these may have been due to sudden unexpected death in epilepsy (SUDEP). Possible SUDEP was the likely cause in another 7%. Mortality in people with ACE was more than 6-fold greater than expected (Ngugi et al., 2014).
Whilst in developing countries verbal autopsy may be the only means of establishing a possible or probable cause of death, the technique of verbal autopsy may have a different use in more affluent countries. As a defined technique it can help to clarify questions not answered by the standard methods of coroner’s and post-mortem reports and not available in medical records, an outcome that has been observed in epilepsy-related death.
Coyle et al. (1994) observed that the incidence of SUDEP might be difficult to ascertain due to variations in reporting the cause of death when investigated by coroners. They examined this problem using a ‘cuttings service’ in the UK press, during 1992, to identify all likely cases of SUDEP. As required by UK law, these unexplained deaths were investigated by pathologists and coroners. All relevant information, including post-mortem reports and witness statements were considered in the 40 SUDEP cases. It was noted that there were inconsistencies in the investigations performed and the observations documented at the time of death, with widely differing degrees of detail concerning the type and history of epilepsy being found. In 70% of these cases, the type of seizure was not documented. Inconsistencies were also found concerning details of AED use, position of the body, toxicology reporting and the detailed exams of organs, including the brain. The causes of death attributed to the cases varied greatly, with epilepsy noted as a primary cause of death in less than half of the cases. Coroner verdicts varied, with no distinct pattern emerging in relation to attributed cause of death. Wide variation in practice of individual corners and pathologists in the investigation and registering of sudden deaths reflected inconsistent quality of performance.
The verbal autopsy was utilised by Nashef et al. (1998) to glean information about the circumstances of sudden death in epilepsy in the UK. Interviews were conducted with relatives of epilepsy patients who had died suddenly. These data were combined with information derived from coroners’ reports, post-mortem reports, previous medical records, and EEG data allowing for more detailed information than would normally be available. Thus, the verbal autopsy was a useful supplement to the other data available and was helpful in addressing the importance to bereaved relatives of having ante-mortem knowledge of the possible risk. Most relatives stated they would have preferred to have been told that epilepsy could be fatal. The interviews emphasized the needs of the bereaved relatives and their sense of isolation in the face of an unexpected death (Nashef et al., 1998).
The purpose of verbal autopsy can be multifaceted. When used in conjunction with post-mortem autopsy data from persons with SUDEP, such retrospective data can provide additional help in identifying more accurately the cause of death and in conducting retrospective analysis of these post-mortem examinations. The value of this cumulative data from all sources is that it provides information for future preventative policy. In circumstances where post-mortem information was not or could not be collected, verbal autopsies offer a method to find useful information regarding the cause of death, whether conducted in developing countries or in developed countries. In either case, filling so many of the gaps in the worldwide database on persons with epilepsy who die suddenly and unexpectedly will help in determining the prevalence of SUDEP and the quest for identification of preventive interventions.
How to cite:
Lathers CM & Schraeder PL. Verbal autopsy and SUDEP. In: Hanna J, Panelli R, Jeffs T, Chapman D, editors. Continuing the global conversation [online]. SUDEP Action, SUDEP Aware & Epilepsy Australia; 2014 [retrieved day/month/year]. Available from: www.sudepglobalconversation.com.