Year : 2021 | Volume
: 24 | Issue : 3 | Page : 313--314
Predicting the unpredictable: Utility of outcome prediction scores in status epilepticus
Lakshminarayanan Kannan1, Chaturbhuj Rathore2,
1 Advanced Centre for Epilepsy, Gleneagles Global Health City, Chennai, Tamil Nadu, India
2 Department of Neurology, Smt. B. K. Shah Medical Institute and Research Center, Sumandeep Vidyapeeth, Vadodara, Gujarat, India
Dr. Chaturbhuj Rathore
Department of Neurology, Smt. B. K. Shah Medical Institute and Research Center, Sumandeep Vidyapeeth, Piparia, Waghodiya, Vadodara, Gujarat - 391760
|How to cite this article:|
Kannan L, Rathore C. Predicting the unpredictable: Utility of outcome prediction scores in status epilepticus.Ann Indian Acad Neurol 2021;24:313-314
|How to cite this URL:|
Kannan L, Rathore C. Predicting the unpredictable: Utility of outcome prediction scores in status epilepticus. Ann Indian Acad Neurol [serial online] 2021 [cited 2021 Aug 3 ];24:313-314
Available from: https://www.annalsofian.org/text.asp?2021/24/3/313/316501
Status epilepticus (SE) is one of the commonest neurological emergencies that is associated with significant morbidity and mortality. In-hospital mortality rates in SE vary from 10% to 35%, largely determined by the underlying etiology. Apart from treating the underlying etiology, the major focus during the management of SE is on the early and aggressive control of seizures. While aggressive seizure control may prevent neuronal damage and improve the outcome, it may also lead to treatment-related complications especially with the prolonged use of the anesthetic agents. This fact underscores the importance of early prediction of prognosis in SE which can help in management decisions as well as in counseling the family.
Many attempts have been made to develop prognostic scores to predict short-term mortality and long-term functional outcomes in patients with SE. To be clinically useful, such a score should be clinically relevant, comprehensive yet simple to apply, and have a good predictive value. Status epilepticus severity score (STESS) was the first such score developed in 2006 to predict the risk of mortality in patients with SE. This score was based on four variables: (i) age, (ii) extent of consciousness impairment, (iii) seizure type, and (iv) the past history of epilepsy. It is a six-point score and a score of ≥3 predicted a high risk of death in patients with SE. The score showed a negative predictive value of 100% suggesting that a score of <3 always predicted survival. Although future studies with different population groups have shown relatively less robust results,,, its simple design and ability to predict the outcome at the time of presentation without the need for any investigation make it a useful tool. Subsequently, with an aim to include the etiology in predicting prognosis, Epidemiology-based mortality score in SE (EMSE) was developed in 2015. This score is based on four parameters; etiology, age, co-morbidities, and EEG findings. This is a more elaborate score and has been shown to have a better predictive value compared to STESS and it can predict both good and poor outcomes.,
Encephalitis-nonconvulsive status epilepticus-Diazepam resistance-imaging-tracheal intubation (END-IT) score was developed in 2016 in a retrospective exploratory analysis among patients aged >12 years with an aim to predict long-term functional outcomes. END-IT score utilizes five independent clinical parameters that are mostly available in any setting caring for the patients with SE. Thus END-IT score is simple, based on readily available variables, easy to compute, and can be utilized routinely at the bedside to predict outcomes. Although it showed a better predictive value compared to STESS and EMSE in the original cohort, this finding has not been replicated in other external validity studies. It is also dependent on EEG and imaging results which may not be readily available early in the course of SE and the score may have a lower predictive value in settings where encephalitis is not a predominant etiology. Moreover, the score does not differentiate between acute and chronic imaging findings, both of which have different prognostic values.
As these scores were mainly developed in the adult population, researchers have made attempts to validate these scores in the pediatric population. In the current issue of the journal, Sharma and colleagues report a retrospective study validating END-IT score in SE among pediatric patients aged <12 years. They used the same retrospective cohort which they have used earlier to validate STESS in the pediatric population. Study population and their baseline characteristics including the etiological break-up are relatable to the usual scenario in developing countries. They report that a score of >2 has an NPV of 99% to predict mortality as well as the poor functional outcome at the time of discharge. Similar to the study in the adults, it had a low positive predictive value and an accuracy of 0.76. The study shows that the utility of the END-IT score in pediatric patients is similar to that of adults.
However, the study has certain limitations. The authors have used only a retrospective cohort and have not tried to validate the score in an additional prospective cohort. Additionally, majority of the patients having mild and benzodiazepine responsive SE, non-availability of EEG and MRI in all the patients, and EEG recordings of only 1 h also limit the generalizability of the results. The authors have assessed the outcomes at the time of discharge and not at 3 months as it was done in the original study. Although the effort by the authors, especially in the low resource setting, is commendable, these drawbacks call for a prospective study to validate END-IT score in pediatric patients with SE of variable severity.
This leaves us with the question of the utility of these prognostic scores in the real-world clinical setting. As is true with all the conditions in medicine, each patient with SE is different and the treatment decisions need to be individualized especially in the setting of refractory and super-refractory SE. The approximate 80% accuracy of all these scores suggests that these scores can only provide broad guidelines at group levels and will not be useful in making treatment decisions in an individual patient. For the same reason, these scores are not widely used by clinicians. In developing countries, these scores may be used for deciding the referral of the patients from the primary care setting to a more advanced setting after proper validation. Further development of the scores to predict long-term seizure, cognitive, memory, and behavior outcomes may be more clinically relevant. Until then researchers will continue to predict the unpredictable while clinicians will continue to strike a compromise between Scylla and Charybdis.
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