The Established Status Epilepticus Treatment Trial was a blinded, comparative-effectiveness study of fosphenytoin, levetiracetam, and valproic acid in benzodiazepine-refractory status epilepticus. The primary outcome was clinical seizure cessation and increased responsiveness without additional anticonvulsant medications. Weight-based dosing was capped at 75 kg. Hence, patients weighing >75 kg received a lower mg/kg dose. Logistic regression models were developed in 235 adults to determine the association of weight (≤ or >75 kg, ≤ or >90 kg), sex, treatment, and weight-normalized dose with the primary outcome and solely seizure cessation. The primary outcome was achieved in 45.1% and 42.5% of those ≤75 kg and >75 kg, respectively. Using univariate analyses, the likelihood of success for those >75 kg (odds ratio [OR] = 0.9, 95% confidence interval [CI] = 0.54-1.51) or >90 kg (OR = 0.85, 95% CI = 0.42-1.66) was not statistically different compared with those ≤75 kg or ≤90 kg, respectively. Similarly, other predictors were not significantly associated with primary outcome or clinical seizure cessation. Our findings suggest that doses, capped at 75 kg, likely resulted in concentrations greater than those needed for outcome. Studies that include drug concentrations and heavier individuals are needed to confirm these findings.

Objective

This study was undertaken to describe patterns of benzodiazepine use as first-line treatment of status epilepticus (SE) and test the association of benzodiazepine doses with response to second-line agents in patients enrolled in the Established Status Epilepticus Treatment Trial (ESETT).

Methods

Patients refractory to an adequate dose of benzodiazepines for the treatment of SE were enrolled in ESETT. Choice of benzodiazepine, doses given prior to administration of second-line agent, route of administration, setting, and patient weight were characterized. These were compared with guideline-recommended dosing. Logistic regression was used to determine the association of the first dose of benzodiazepine and the cumulative benzodiazepine dose with the response to second-line agent.

Results

Four hundred sixty patients were administered 1170 doses of benzodiazepines (669 lorazepam, 398 midazolam, 103 diazepam). Lorazepam was most frequently administered intravenously in the emergency department, midazolam intramuscularly or intravenously by the emergency medical services personnel, and diazepam rectally prior to ambulance arrival. The first dose of the first benzodiazepine (N = 460) was lower than guideline recommendations in 76% of midazolam administrations and 81% of lorazepam administrations. Among all administrations, >85% of midazolam and >76% of lorazepam administrations were lower than recommended. Higher first or cumulative benzodiazepine doses were not associated with better outcomes or clinical seizure cessation in response to second-line medications in these benzodiazepine-refractory seizures.

Significance

Benzodiazepines as first-line treatment of SE, particularly midazolam and lorazepam, are frequently underdosed throughout the United States. This broad and generalizable cohort confirms prior single site reports that underdosing is both pervasive and difficult to remediate. (ESETT ClinicalTrials.gov identifier: NCT01960075.).

Fosphenytoin (FOS) and its active form, phenytoin (PHT), levetiracetam (LEV), and valproic acid (VPA) are commonly used second-line treatments of status epilepticus. However, limited information is available regarding LEV and VPA concentrations following high intravenous doses, particularly in young children. The Established Status Epilepticus Treatment Trial, a blinded, comparative effectiveness study of FOS, LEV, and VPA for benzodiazepine-refractory status epilepticus provided an opportunity to investigate early drug concentrations. Patients aged ≥2 years who continued to seizure despite receiving adequate doses of benzodiazepines were randomly assigned to FOS, LEV, or VPA infused over 10 minutes. A sparse blood-sampling approach was used, with up to 2 samples collected per patient within 2 hours following drug administration. The objective of this work was to report early drug exposure of PHT, LEV, and VPA and plasma protein binding of PHT and VPA. Twenty-seven children with median (interquartile range) age of 4 (2.5-6.5) years were enrolled. The total plasma concentrations ranged from 69 to 151.3 μg/mL for LEV, 11.3 to 26.7 μg/mL for PHT and 126 to 223 μg/mL for VPA. Free fraction ranged from 4% to 19% for PHT and 17% to 51% for VPA. This is the first report in young children of LEV concentrations with convulsive status epilepticus as well as VPA concentrations after a 40 mg/kg dose. Several challenges limited patient enrollment and blood sampling. Additional studies with a larger sample size are required to evaluate the exposure-response relationships in this emergent condition.

Convulsive status epilepticus (SE) is a relatively common emergency condition affecting individuals of all ages. The primary goal of treatment is prompt termination of seizures. Where first-line treatment with benzodiazepine has failed to achieve this, a condition known as established SE (ESE), there is uncertainty about which agent to use next. The Established Status Epilepticus Treatment Trial (ESETT) is a 3-arm (valproate (VPA), fosphenytoin (FOS), levetiracetam (LEV)), phase III, double-blind randomized comparative effectiveness study in patients aged 2 years and above with established convulsive SE. Enrollment was completed in January 2019, and the results are expected later this year. We discuss lessons learnt during the conduct of the study in relation to the following: ethical considerations; trial design and practical implementation in emergency settings, including pediatric and adult populations; quality assurance; and outcome determination where treating emergency clinicians may lack specialist expertise. We consider that the ESETT is already informing both clinical practice and future trial design. This article is part of the Special Issue "Proceedings of the 7th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures".

Objective

To quantify the association between early neurologic recovery, practice pattern variation, and endotracheal intubation during established status epilepticus, we performed a secondary analysis within the cohort of patients enrolled in the Established Status Epilepticus Treatment Trial (ESETT).

Methods

We evaluated factors associated with the endpoint of endotracheal intubation occurring within 120 minutes of ESETT study drug initiation. We defined a blocked, stepwise multivariate regression, examining 4 phases during status epilepticus management: (1) baseline characteristics, (2) acute treatment, (3) 20-minute neurologic recovery, and (4) 60-minute recovery, including seizure cessation and improving responsiveness.

Results

Of 478 patients, 117 (24.5%) were intubated within 120 minutes. Among high-enrolling sites, intubation rates ranged from 4% to 32% at pediatric sites and 19% to 39% at adult sites. Baseline characteristics, including seizure precipitant, benzodiazepine dosing, and admission vital signs, provided limited discrimination for predicting intubation (area under the curve [AUC] 0.63). However, treatment at sites with an intubation rate in the highest (vs lowest) quartile strongly predicted endotracheal intubation independently of other treatment variables (adjusted odds ratio [aOR] 8.12, 95% confidence interval [CI] 3.08-21.4, model AUC 0.70). Site-specific variation was the factor most strongly associated with endotracheal intubation after adjustment for 20-minute (aOR 23.4, 95% CI 6.99-78.3, model AUC 0.88) and 60-minute (aOR 14.7, 95% CI 3.20-67.5, model AUC 0.98) neurologic recovery.

Conclusions

Endotracheal intubation after established status epilepticus is strongly associated with site-specific practice pattern variation, independently of baseline characteristics, and early neurologic recovery and should not alone serve as a clinical trial endpoint in established status epilepticus.

Trial registration information

ClinicalTrials.gov Identifier: NCT01960075.