Status epilepticus in Auckland, New Zealand: Incidence, etiology, and outcomes

Objective: To determine the incidence, etiology, and outcome of status epilepticus (SE) in Auckland, New Zealand, using the latest International League Against Epilepsy (ILAE) SE semiological classification.

Methods: We prospectively identified patients presenting to the public or major private hospitals in Auckland (population = 1.61 million) between April 6, 2015 and April 5, 2016 with a seizure lasting 10 minutes or longer, with retrospective review to confirm completeness of data capture. Information was recorded in the EpiNet database.

Results: A total of 477 episodes of SE occurred in 367 patients. Fifty-one percent of patients were aged <15 years. SE with prominent motor symptoms comprised 81% of episodes (387/477). Eighty-four episodes (18%) were nonconvulsive SE. Four hundred fifty episodes occurred in 345 patients who were resident in Auckland. The age-adjusted incidence of 10-minute SE episodes and patients was 29.25 (95% confidence interval [CI] = 27.34-31.27) and 22.22 (95% CI = 20.57-23.99)/100 000/year, respectively. SE lasted 30 minutes or longer in 250 (56%) episodes; age-adjusted incidence was 15.95 (95% CI = 14.56-17.45) SE episodes/100 000/year and 12.92 (95% CI = 11.67-14.27) patients/100 000/year. Age-adjusted incidence (10-minute SE) was 25.54 (95% CI = 23.06-28.24) patients/100 000/year for males and 19.07 (95% CI = 16.91-21.46) patients/100 000/year for females. The age-adjusted incidence of 10-minute SE was higher in Māori (29.31 [95% CI = 23.52-37.14]/100 000/year) and Pacific Islanders (26.55 [95% CI = 22.05-31.99]/100 000/year) than in patients of European (19.13 [95% CI = 17.09-21.37]/100 000/year) or Asian/other descent (17.76 [95% CI = 14.73-21.38]/100 000/year). Seventeen of 367 patients in the study died within 30 days of the episode of SE; 30-day mortality was 4.6%.

Significance: In this population-based study, incidence and mortality of SE in Auckland lie in the lower range when compared to North America and Europe. For pragmatic reasons, we only included convulsive SE if episodes lasted 10 minutes or longer, although the 2015 ILAE SE classification was otherwise practical and easy to use.