Identification of Generalized Convulsive Status Epilepticus from Emergency Medical Service Records: A Validation Study of Diagnostic Coding.

BACKGROUND: Generalized convulsive status epilepticus (GCSE) is a neurologic emergency demanding prehospital identification and treatment. Evaluating real-world practice requires accurately identifying the target population; however, it is unclear whether emergency medical services (EMS) documentation accurately identifies patients with GCSE. OBJECTIVE: To evaluate the validity of EMS diagnostic impressions for GCSE. METHODS: This was an analysis of electronic medical records of a California county EMS system from 2013 to 2018. We identified all cases with a primary diagnostic impression of "seizure-active," "seizure-post," or "seizure-not otherwise specified (NOS)" and within each diagnostic category, we randomly selected 75 adult and 25 pediatric records. Two authors reviewed the provider narrative of these 300 charts to determine a clinical seizure diagnosis according to prespecified definitions. We calculated a kappa for interrater reliability of the clinical diagnosis. We then calculated the positive predictive value (PPV), sensitivity, and specificity of an EMS diagnosis of "seizure-active" diagnosis for identifying GCSE. Sensitivity and specificity calculations were weighted according to the distribution of seizure cases in the overall population. We performed a descriptive analysis of records with an incorrect EMS diagnosis of GCSE or seizure. RESULTS: Of 38,995 total records for seizure, there were 3401 (8.7%) seizure-active cases, 12,478 (32.0%) seizure-NOS cases, and 23,116 (59.4%) seizure-post cases. An EMS diagnosis of "seizure-active" had a PPV of 65.0% (95% CI 54.8-74.3), sensitivity of 54.6% (95% confidence interval [CI] 39.3-69.0), and specificity of 96.6% (95% CI 95.1-97.6) for capturing GCSE. Limiting the case definition to patients who received an EMS diagnosis of "seizure-active" and were treated with a benzodiazepine increased the PPV (80.2%; 95% CI 69.9-88.2) and specificity (99.3%; 95% CI 98.7-99.6) while the sensitivity decreased (25.1%; 95% CI 17.0-35.3). Across the 300 records reviewed, there were 19 (6.3%) patients who had a non-seizure related diagnosis including non-epileptic spells (7 records), altered mental status (8 records), tremors (2 records), anxiety (1 record), and stroke (1 record). CONCLUSIONS: EMS diagnostic impressions have reasonable PPV and specificity but low sensitivity for GCSE. Improved coding algorithms and training will allow for improved benchmarking, quality improvement, and research about this neurologic emergency.

Prehospital midazolam use and outcomes among patients with out-of-hospital status epilepticus.

OBJECTIVE: To examine the use of benzodiazepines and the association between low benzodiazepine dose, breakthrough seizures, and respiratory support in patients with status epilepticus. METHODS: In this cross-sectional analysis of adult patients with status epilepticus treated by an emergency medical services agency from 2013 to 2018, the primary outcome was treatment with a second benzodiazepine dose, an indicator for breakthrough seizure. The secondary outcome was receiving respiratory support. Midazolam was the only benzodiazepine administered. RESULTS: Among 2,494 patients with status epilepticus, mean age was 54.0 years and 1,146 (46%) were female. There were 1,537 patients given midazolam at any dose, yielding an administration rate of 62%. No patients received a dose and route consistent with national guidelines. Rescue therapy with a second midazolam dose was required in 282 (18%) patients. Higher midazolam doses were associated with lower odds of rescue therapy (odds ratio [OR], 0.8; 95% confidence interval [CI], 0.7-0.9) and were not associated with increased respiratory support. If anything, higher doses of midazolam were associated with decreased need for respiratory support after adjustment (OR, 0.9; 95% CI, 0.8-1.0). CONCLUSIONS: An overwhelming majority of patients with status epilepticus did not receive evidence-based benzodiazepine treatment. Higher midazolam doses were associated with reduced use of rescue therapy and there was no evidence of respiratory harm, suggesting that benzodiazepines are withheld without clinical benefit. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that for patients with status epilepticus, higher doses of midazolam led to a reduced use of rescue therapy without an increased need for ventilatory support.