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Role of EMSE and STESS scores in the outcome evaluation of status epilepticus
Epilepsy & Behavior 64 (2016) 140–142
Contents lists available at ScienceDirect
Epilepsy & Behavior journal homepage: www.elsevier.com/locate/yebeh
Brief Communication
Role of EMSE and STESS scores in the outcome evaluation of status epilepticus María Sol Pacha a,⁎, Lucas Orellana b, Emanuel Silva a, Glenda Ernst a, Fatima Pantiu a, Julieta Quiroga Narvaez a, Ricardo Reisin a, Oscar Martinez a,b a b
Department of Neurology, Hospital Británico, Buenos Aires, Argentina Epilepsy Area, Department of Neurology, Hospital de Clínicas “José de San Martín”, Buenos Aires, Argentina
a r t i c l e
i n f o
Article history: Received 28 August 2016 Revised 20 September 2016 Accepted 20 September 2016 Available online xxxx Keywords: Mortality STESS EMSE Outcome Score Status epilepticus
a b s t r a c t Status epilepticus (SE) is a severe neurological condition with significant morbidity and mortality. A reliable tool for prognosis is needed to take decision regarding treatment strategies. We compared 2 available prognostic scores of outcome: the Status Epilepticus Severity Score (STESS) and the Epidemiology-based Mortality score in SE (EMSE). We included 46 patients with SE evaluated out the last 5 years in our hospital. We excluded patients with postanoxic encephalopathy or incomplete data. Among the 46 patients with SE, in-hospital mortality was 28%. The receiver operating characteristic (ROC) curve for predicting of death by STESS had an area under the curve (AUC) of 0.80 with cutoff point ≥4. The best EMSE variable combination to predict mortality was EMSE-AEL using an optimized cutoff point of 34 (age/etiology/loss of consciousness) with an area under the ROC of 0.79. The STESS and EMSE would be useful tools to predict in-hospital mortality in SE. © 2016 Elsevier Inc. All rights reserved.
1. Introduction Status epilepticus (SE) is a neurological emergency, and many patients who survive have persistent neurological deficits. It is crucial to have a clinical tool to predict the risk of death at SE onset. Only 2 clinical scoring systems are available: “The Status Epilepticus Severity Score (STESS)” and “The Epidemiology-based Mortality score in SE (EMSE)” [1,2]. The STESS has been previously validated by Rossetti et al. in a prospective cohort and in three other studies [3,4]. The second scoring system was published by Leitinger et al. through a retrospective study and was validated in a multicenter study [3]. We compared these two scoring systems to predict the risk of death in our population. 2. Methods 2.1. Design We performed a retrospective analysis of our clinical and electroencephalographic (EEG) database for all adults with SE from January
⁎ Corresponding author at: Hospital Británico de Buenos Aires, Buenos Aires, Perdriel 74, 1° Floor, CP 1280AEB, Argentina. E-mail address: [email protected] (M.S. Pacha).
http://dx.doi.org/10.1016/j.yebeh.2016.09.036 1525-5050/© 2016 Elsevier Inc. All rights reserved.
2009 to December 2014. The study received the approval of the institutional review board. 2.2. Patients and variables Status epilepticus was defined as clinical and EEG evidence of seizure activity that lasted at least 5 min or as a series of epileptic seizures without complete clinical recovery in between. The EEGs were reviewed by two electroencephalographers; EEGcriteria for NCSE were based on Beniczky et al. [5]. Demographic data recorded included the following: age, gender, level of consciousness, seizure type, history of previous seizures, etiology of SE, comorbidity by Charlson Comorbidity Index [6], and onset EEG. The STESS score included the following: level of consciousness (alert or somnolent/confused = 0 points, stuporous or comatose = 1 point), “worst” seizure type (simple-partial, complex-partial, absence, myoclonic as complicating idiopathic generalized epilepsy = 0 points; generalized–convulsive = 1 point; nonconvulsive SE in coma = 2 points), age (under 65 years = 0 points, 65 or older = 2 points), and history of previous seizures (yes = 0 points, no or unknown = 1 point). A score of three points or higher indicates risk of death. The EMSE score included the following: etiology, age, comorbidity, EEG, duration, and level of consciousness. The EMSE-EAC (etiology–age– comorbidity) score of ≥27 or EMSE-EACE (etiology–age–comorbidity– EEG) score of ≥64 indicates risk of death.
M.S. Pacha et al. / Epilepsy & Behavior 64 (2016) 140–142 Table 1 Characteristics in survivor and nonsurvivor patients. Survival
Nonsurvival
p
Patients [n, (%)] Gender (F) Age, year (mean)
33 (71.7%) 23 68.9
13 (28%) 9 76.9
b1.0 b1.0
Etiology Acute symptomatic Remote unprovoked Symptomatic seizure/progress disease Unprovoked unknown etiology History of previous seizures
17 (51.5%) 4 (12.1%) 5 (15.1%) 7 (21.21%) 4 (12.1%)
10 (76.9%) 1 (7.7%) 1 (7.7%) 1 (7.7%) 0
b0.18 b1.0 b0.65 b0.41 b0.43
23 (69.7%)
5 (38%)
b0.09
8 (24.2%) 2 (6%)
2 (15.38%) 6 (46.1%)
b0.70 b0.004
3 (9%) 20 (60.6%) 9 (27.2%) 1 (3%) 8 (24.2%) 18 (54.5%) 7 (21.2%)
0 4 (30.7%) 4 (30.7%) 5 (38.4%) 0 7 (53.8%) 6 (46.2%)
b0.54 b0.067 b1.0 b0.05 b1.0 b0.084 b0.14
Seizure type Simple-partial, complex-partial, absence, myoclonic Generalized–convulsive NCSE Level of consciousness Awake Somnolent/confused Stupor Coma CCI 0 (% of patients) CCI 1–2 CCI 3 or more
NCSE: nonconvulsive status epilepticus; CCI: Charlson Comorbidity Index.
2.3. Outcome The primary outcome parameter of STESS and EMSE was in-hospital death. 2.4. Statistical analyses Data were presented as percentage for categorical variables or as mean and standard error for numerical variables. Areas under receiver operating characteristic (ROC) curves, sensitivity (S), specificity (Sp), likelihood ratios (LR + and LR −), positive and negative predictive values (PPV and NPV, respectively), and accuracy were calculated for the EMSE and STESS.
A)
For categorical variables, Fisher test was performed. Probability values of b 0.05 were considered statistically significant. The statistical analysis was carried out with SPSS 22.0 (SPSS Inc.) software and MedCalc Statistical Software version 14. To determine the optimal combination of EMSE variables, we chose EMSE combinations for in-hospital death that had a high sensitivity (N0.7) and specificity (N0.7) at the calculated cutoff point [3]. 3. Results We identified 65 patients with SE in our database; nevertheless, 15 of them were excluded because of incomplete clinical or EEG information as well as 4 patients with postanoxic encephalopathy. Among the 46 patients (32 females), the mean age was 70.9 ± 2.2 years old (range: 16–99); the most frequent etiologies of SE were systemic infection (23.9%), stroke (19.5%), and cryptogenic (10.8%). Only 12.1% of the patients had a history of previous seizures (Table 1). In the evaluation of comorbidity by Charlson Comorbidity Index (CCI), the survivor group had 24.2% of noncomorbidity (p b 1.0), 54.5% had 1 or 2 comorbidity (p b 0.084), and 21.2% had 3 or more comorbidity (p b 0.14); these findings were not statistically significant. Nonconvulsive SE and coma were associated with in-hospital mortality (p b 0.005). The sensitivity (S) and specificity (Sp) of STESS with cutoff point ≥3 were 61.5% and 75.7%, respectively. Additionally, using STESS with a cutoff point ≥ 4, we found an S of 96.9% and a Sp of 53.8% with an AUC-ROC curve of 0.80 with a 95% confidence interval (CI 95%) of 0.66–0.90. However, EMSE-EAC with a cutoff value of 37 points showed a S of 43.7% with a Sp of 92.3% (AUC-ROC: 0.69 with CI 95%: 0.53–0.82), and EMSE-EACE with a cutoff value of 64 points has a S of 24.2% with a Sp of 92.3% (AUC-ROC: 0.70 with CI 95%: 0.55–0.83). Our findings showed that the best EMSE variable combination was EMSE-AEL (age/etiology/ loss of consciousness) with an optimized cutoff point of 34, S of 78.9%, and Sp of 69.2% (AUC-ROC: 0.79 with CI 95%: 0.65–0.90) (Fig. 1). 4. Discussion Status epilepticus is a serious neurologic emergency with a shortterm mortality of 7–39%; we found 28% in-hospital mortality in accordance with previous findings [7,8]. Although, it has been previously described as variables of poor outcome: older age, acute symptomatic
B)
AUC-ROC: 0.80 ±0.07 p< 0.0001 S: 53.8 95% CI: 25.1 -80.8 Sp: 96.9. 95% CI: 84.2 -99.9 LR+: 17.77 LR-: 0.48 PPV: 34.5 NPV: 80.8
141
AUC-ROC: 0.70 ±0.08 p< 0.001 S: 24.2 95% CI: 9.0 -38.9 Sp: 92.3 95% CI: 64.0 -99.8 LR+: 1.17 LR-: 0.36 PPV: 29.5 NPV: 95.7
C)
AUC-ROC: 0.79 ±0.07 p< 0.0001 S:78.9 95% CI: 61.1 -91.0 Sp: 69.2 95% CI: 38.6 -90.9 LR+: 2.5 LR-: 0.3 PPV: 45.4 NPV: 91.3
Fig. 1. Receiver operating characteristics for STESS, EMSE-EACE and EMSE-EAL.
142
M.S. Pacha et al. / Epilepsy & Behavior 64 (2016) 140–142
etiology, type of SE, and degree of alteration of consciousness [9]; in our population, we identified only NCSE and coma. Findings of this study have shown that STESS score could contribute to predict bad outcome using both cutoff points ≥ 3 and ≥ 4. The first report of STESS score used a cutoff point ≥3 [1]; however, it has been recently published that a cutoff point ≥ 4 from STESS score would be the better predictor of survival in SE [2–4]. We observed that the best combination of EMSE score variables was given excluding comorbidity as a variable. We did not find statistical differences between the CCI score survival group and CCI nonsurvival group. Moreover, in this studied population, only 24.2% had noncomorbidity compared with 43.5% showed previously by Leitinger [2]. In fact, Alvarez et al. evaluated the importance of comorbidities in outcome prediction after status epilepticus, and they concluded that medical comorbidities increase relatively marginally the prediction accuracy of SE outcome [10]. Sutter et al. found that Charlson Comorbidity Index would be an independent variable of poor outcome [11]. Predicting outcome in SE has become a challenge. To improve the medical strategies, the score must be analyzed according to different demographic characteristics. 5. Conclusion This present study showed that, in our population, STESS and EMSE scores are useful tools to predict mortality. New studies with a higher number of patients with SE would be necessary to confirm our results. Disclosure None of the authors has any conflict of interest to disclose.
We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this report is consistent with those guidelines.
References [1] Rossetti AO, Logroscino G, Milligan TA, Michaelides C, Ruffieux C, Bromfield EB. Status epilepticus severity score (STESS): a tool to orient early treatment strategy. J Neurol 2008;255(10):1561–6. [2] Leitinger M, Höller Y, Kalss G, Rohracher A, Novak HF, Höfler J. Epidemiology-based mortality score in status epilepticus (EMSE). Neurocrit Care 2015;22:273–82. [3] Kang BS, Kim DW, Kim KK, Moon HJ, Kim Y-S, Kim HK, et al. Prediction of mortality and functional outcome from status epilepticus and independent external validation of STESS and EMSE scores. Crit Care 2015;20(1):25. [4] Sutter R, Kaplan PW, Rüegg S. Independent external validation of the status epilepticus severity score. Crit Care Med 2013;41(12):e475–9 [Internet]. [5] Beniczky S, Hirsch LJ, Kaplan PW, Pressler R, Bauer G, Aurlien H, et al. Unified EEG terminology and criteria for nonconvulsive status epilepticus. Epilepsia 2013; 54(Suppl. 6):28–9. [6] Charlson ME, Pompei P, Ales KL, MacKenzie CR. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chronic Dis 1987;40(5):373–83. [7] Logroscino G, Hesdorffer DC, Cascino G, Annegers JF, Hauser WA. Short-term mortality after a first episode of status epilepticus. Epilepsia 1997;38(12): 1344–9. [8] Coeytaux A, Jallon P, Galobardes B, Morabia A. Incidence of status epilepticus in French-speaking Switzerland: (EPISTAR). Neurology 2000;55(5):693–7. [9] Chin RFM, Neville BGR, Scott RC. A systematic review of the epidemiology of status epilepticus. Eur J Neurol 2004;11(12):800–10. [10] Alvarez V, Januel JM, Burnand B, Rossetti AO. Role of comorbidities in outcome prediction after status epilepticus. Epilepsia 2012;53(5):89–92. [11] Sutter R, Valenca M, Tschudin-Sutter S, Ruegg S, Marsch S. Procalcitonin and mortality in status epilepticus: an observational cohort study. Crit Care 2015;19(1): 1–10.
Contents lists available at ScienceDirect
Epilepsy & Behavior journal homepage: www.elsevier.com/locate/yebeh
Brief Communication
Role of EMSE and STESS scores in the outcome evaluation of status epilepticus María Sol Pacha a,⁎, Lucas Orellana b, Emanuel Silva a, Glenda Ernst a, Fatima Pantiu a, Julieta Quiroga Narvaez a, Ricardo Reisin a, Oscar Martinez a,b a b
Department of Neurology, Hospital Británico, Buenos Aires, Argentina Epilepsy Area, Department of Neurology, Hospital de Clínicas “José de San Martín”, Buenos Aires, Argentina
a r t i c l e
i n f o
Article history: Received 28 August 2016 Revised 20 September 2016 Accepted 20 September 2016 Available online xxxx Keywords: Mortality STESS EMSE Outcome Score Status epilepticus
a b s t r a c t Status epilepticus (SE) is a severe neurological condition with significant morbidity and mortality. A reliable tool for prognosis is needed to take decision regarding treatment strategies. We compared 2 available prognostic scores of outcome: the Status Epilepticus Severity Score (STESS) and the Epidemiology-based Mortality score in SE (EMSE). We included 46 patients with SE evaluated out the last 5 years in our hospital. We excluded patients with postanoxic encephalopathy or incomplete data. Among the 46 patients with SE, in-hospital mortality was 28%. The receiver operating characteristic (ROC) curve for predicting of death by STESS had an area under the curve (AUC) of 0.80 with cutoff point ≥4. The best EMSE variable combination to predict mortality was EMSE-AEL using an optimized cutoff point of 34 (age/etiology/loss of consciousness) with an area under the ROC of 0.79. The STESS and EMSE would be useful tools to predict in-hospital mortality in SE. © 2016 Elsevier Inc. All rights reserved.
1. Introduction Status epilepticus (SE) is a neurological emergency, and many patients who survive have persistent neurological deficits. It is crucial to have a clinical tool to predict the risk of death at SE onset. Only 2 clinical scoring systems are available: “The Status Epilepticus Severity Score (STESS)” and “The Epidemiology-based Mortality score in SE (EMSE)” [1,2]. The STESS has been previously validated by Rossetti et al. in a prospective cohort and in three other studies [3,4]. The second scoring system was published by Leitinger et al. through a retrospective study and was validated in a multicenter study [3]. We compared these two scoring systems to predict the risk of death in our population. 2. Methods 2.1. Design We performed a retrospective analysis of our clinical and electroencephalographic (EEG) database for all adults with SE from January
⁎ Corresponding author at: Hospital Británico de Buenos Aires, Buenos Aires, Perdriel 74, 1° Floor, CP 1280AEB, Argentina. E-mail address: [email protected] (M.S. Pacha).
http://dx.doi.org/10.1016/j.yebeh.2016.09.036 1525-5050/© 2016 Elsevier Inc. All rights reserved.
2009 to December 2014. The study received the approval of the institutional review board. 2.2. Patients and variables Status epilepticus was defined as clinical and EEG evidence of seizure activity that lasted at least 5 min or as a series of epileptic seizures without complete clinical recovery in between. The EEGs were reviewed by two electroencephalographers; EEGcriteria for NCSE were based on Beniczky et al. [5]. Demographic data recorded included the following: age, gender, level of consciousness, seizure type, history of previous seizures, etiology of SE, comorbidity by Charlson Comorbidity Index [6], and onset EEG. The STESS score included the following: level of consciousness (alert or somnolent/confused = 0 points, stuporous or comatose = 1 point), “worst” seizure type (simple-partial, complex-partial, absence, myoclonic as complicating idiopathic generalized epilepsy = 0 points; generalized–convulsive = 1 point; nonconvulsive SE in coma = 2 points), age (under 65 years = 0 points, 65 or older = 2 points), and history of previous seizures (yes = 0 points, no or unknown = 1 point). A score of three points or higher indicates risk of death. The EMSE score included the following: etiology, age, comorbidity, EEG, duration, and level of consciousness. The EMSE-EAC (etiology–age– comorbidity) score of ≥27 or EMSE-EACE (etiology–age–comorbidity– EEG) score of ≥64 indicates risk of death.
M.S. Pacha et al. / Epilepsy & Behavior 64 (2016) 140–142 Table 1 Characteristics in survivor and nonsurvivor patients. Survival
Nonsurvival
p
Patients [n, (%)] Gender (F) Age, year (mean)
33 (71.7%) 23 68.9
13 (28%) 9 76.9
b1.0 b1.0
Etiology Acute symptomatic Remote unprovoked Symptomatic seizure/progress disease Unprovoked unknown etiology History of previous seizures
17 (51.5%) 4 (12.1%) 5 (15.1%) 7 (21.21%) 4 (12.1%)
10 (76.9%) 1 (7.7%) 1 (7.7%) 1 (7.7%) 0
b0.18 b1.0 b0.65 b0.41 b0.43
23 (69.7%)
5 (38%)
b0.09
8 (24.2%) 2 (6%)
2 (15.38%) 6 (46.1%)
b0.70 b0.004
3 (9%) 20 (60.6%) 9 (27.2%) 1 (3%) 8 (24.2%) 18 (54.5%) 7 (21.2%)
0 4 (30.7%) 4 (30.7%) 5 (38.4%) 0 7 (53.8%) 6 (46.2%)
b0.54 b0.067 b1.0 b0.05 b1.0 b0.084 b0.14
Seizure type Simple-partial, complex-partial, absence, myoclonic Generalized–convulsive NCSE Level of consciousness Awake Somnolent/confused Stupor Coma CCI 0 (% of patients) CCI 1–2 CCI 3 or more
NCSE: nonconvulsive status epilepticus; CCI: Charlson Comorbidity Index.
2.3. Outcome The primary outcome parameter of STESS and EMSE was in-hospital death. 2.4. Statistical analyses Data were presented as percentage for categorical variables or as mean and standard error for numerical variables. Areas under receiver operating characteristic (ROC) curves, sensitivity (S), specificity (Sp), likelihood ratios (LR + and LR −), positive and negative predictive values (PPV and NPV, respectively), and accuracy were calculated for the EMSE and STESS.
A)
For categorical variables, Fisher test was performed. Probability values of b 0.05 were considered statistically significant. The statistical analysis was carried out with SPSS 22.0 (SPSS Inc.) software and MedCalc Statistical Software version 14. To determine the optimal combination of EMSE variables, we chose EMSE combinations for in-hospital death that had a high sensitivity (N0.7) and specificity (N0.7) at the calculated cutoff point [3]. 3. Results We identified 65 patients with SE in our database; nevertheless, 15 of them were excluded because of incomplete clinical or EEG information as well as 4 patients with postanoxic encephalopathy. Among the 46 patients (32 females), the mean age was 70.9 ± 2.2 years old (range: 16–99); the most frequent etiologies of SE were systemic infection (23.9%), stroke (19.5%), and cryptogenic (10.8%). Only 12.1% of the patients had a history of previous seizures (Table 1). In the evaluation of comorbidity by Charlson Comorbidity Index (CCI), the survivor group had 24.2% of noncomorbidity (p b 1.0), 54.5% had 1 or 2 comorbidity (p b 0.084), and 21.2% had 3 or more comorbidity (p b 0.14); these findings were not statistically significant. Nonconvulsive SE and coma were associated with in-hospital mortality (p b 0.005). The sensitivity (S) and specificity (Sp) of STESS with cutoff point ≥3 were 61.5% and 75.7%, respectively. Additionally, using STESS with a cutoff point ≥ 4, we found an S of 96.9% and a Sp of 53.8% with an AUC-ROC curve of 0.80 with a 95% confidence interval (CI 95%) of 0.66–0.90. However, EMSE-EAC with a cutoff value of 37 points showed a S of 43.7% with a Sp of 92.3% (AUC-ROC: 0.69 with CI 95%: 0.53–0.82), and EMSE-EACE with a cutoff value of 64 points has a S of 24.2% with a Sp of 92.3% (AUC-ROC: 0.70 with CI 95%: 0.55–0.83). Our findings showed that the best EMSE variable combination was EMSE-AEL (age/etiology/ loss of consciousness) with an optimized cutoff point of 34, S of 78.9%, and Sp of 69.2% (AUC-ROC: 0.79 with CI 95%: 0.65–0.90) (Fig. 1). 4. Discussion Status epilepticus is a serious neurologic emergency with a shortterm mortality of 7–39%; we found 28% in-hospital mortality in accordance with previous findings [7,8]. Although, it has been previously described as variables of poor outcome: older age, acute symptomatic
B)
AUC-ROC: 0.80 ±0.07 p< 0.0001 S: 53.8 95% CI: 25.1 -80.8 Sp: 96.9. 95% CI: 84.2 -99.9 LR+: 17.77 LR-: 0.48 PPV: 34.5 NPV: 80.8
141
AUC-ROC: 0.70 ±0.08 p< 0.001 S: 24.2 95% CI: 9.0 -38.9 Sp: 92.3 95% CI: 64.0 -99.8 LR+: 1.17 LR-: 0.36 PPV: 29.5 NPV: 95.7
C)
AUC-ROC: 0.79 ±0.07 p< 0.0001 S:78.9 95% CI: 61.1 -91.0 Sp: 69.2 95% CI: 38.6 -90.9 LR+: 2.5 LR-: 0.3 PPV: 45.4 NPV: 91.3
Fig. 1. Receiver operating characteristics for STESS, EMSE-EACE and EMSE-EAL.
142
M.S. Pacha et al. / Epilepsy & Behavior 64 (2016) 140–142
etiology, type of SE, and degree of alteration of consciousness [9]; in our population, we identified only NCSE and coma. Findings of this study have shown that STESS score could contribute to predict bad outcome using both cutoff points ≥ 3 and ≥ 4. The first report of STESS score used a cutoff point ≥3 [1]; however, it has been recently published that a cutoff point ≥ 4 from STESS score would be the better predictor of survival in SE [2–4]. We observed that the best combination of EMSE score variables was given excluding comorbidity as a variable. We did not find statistical differences between the CCI score survival group and CCI nonsurvival group. Moreover, in this studied population, only 24.2% had noncomorbidity compared with 43.5% showed previously by Leitinger [2]. In fact, Alvarez et al. evaluated the importance of comorbidities in outcome prediction after status epilepticus, and they concluded that medical comorbidities increase relatively marginally the prediction accuracy of SE outcome [10]. Sutter et al. found that Charlson Comorbidity Index would be an independent variable of poor outcome [11]. Predicting outcome in SE has become a challenge. To improve the medical strategies, the score must be analyzed according to different demographic characteristics. 5. Conclusion This present study showed that, in our population, STESS and EMSE scores are useful tools to predict mortality. New studies with a higher number of patients with SE would be necessary to confirm our results. Disclosure None of the authors has any conflict of interest to disclose.
We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this report is consistent with those guidelines.
References [1] Rossetti AO, Logroscino G, Milligan TA, Michaelides C, Ruffieux C, Bromfield EB. Status epilepticus severity score (STESS): a tool to orient early treatment strategy. J Neurol 2008;255(10):1561–6. [2] Leitinger M, Höller Y, Kalss G, Rohracher A, Novak HF, Höfler J. Epidemiology-based mortality score in status epilepticus (EMSE). Neurocrit Care 2015;22:273–82. [3] Kang BS, Kim DW, Kim KK, Moon HJ, Kim Y-S, Kim HK, et al. Prediction of mortality and functional outcome from status epilepticus and independent external validation of STESS and EMSE scores. Crit Care 2015;20(1):25. [4] Sutter R, Kaplan PW, Rüegg S. Independent external validation of the status epilepticus severity score. Crit Care Med 2013;41(12):e475–9 [Internet]. [5] Beniczky S, Hirsch LJ, Kaplan PW, Pressler R, Bauer G, Aurlien H, et al. Unified EEG terminology and criteria for nonconvulsive status epilepticus. Epilepsia 2013; 54(Suppl. 6):28–9. [6] Charlson ME, Pompei P, Ales KL, MacKenzie CR. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chronic Dis 1987;40(5):373–83. [7] Logroscino G, Hesdorffer DC, Cascino G, Annegers JF, Hauser WA. Short-term mortality after a first episode of status epilepticus. Epilepsia 1997;38(12): 1344–9. [8] Coeytaux A, Jallon P, Galobardes B, Morabia A. Incidence of status epilepticus in French-speaking Switzerland: (EPISTAR). Neurology 2000;55(5):693–7. [9] Chin RFM, Neville BGR, Scott RC. A systematic review of the epidemiology of status epilepticus. Eur J Neurol 2004;11(12):800–10. [10] Alvarez V, Januel JM, Burnand B, Rossetti AO. Role of comorbidities in outcome prediction after status epilepticus. Epilepsia 2012;53(5):89–92. [11] Sutter R, Valenca M, Tschudin-Sutter S, Ruegg S, Marsch S. Procalcitonin and mortality in status epilepticus: an observational cohort study. Crit Care 2015;19(1): 1–10.