Status epilepticus outcomes among vaccinated and unvaccinated children: A population-based study.

Aim: To determine the proportion of first status epilepticus (SE) cases that are vaccine-proximate (VP-) and compare clinical outcomes to non-vaccine-proximate (NVP-) cases.

Methods: Birth records for 1,440,807 Australian children born in 1998-2012, were probabilistically linked to hospitalizations, deaths, and vaccination history available to 2013. First SE coded hospitalizations were categorized as VP-SE or NVP-SE; clinical severity and post-SE vaccination coverage were compared. SE rates were calculated.

Results: Of 867 first SE cases (7.9 per 100,000 person-years), 31 (3.6%) were VP-SE; 16 followed dose-1 measles vaccine (1.2 SE per 100,000 doses). Compared with NVP-SE, VP-SE cases were younger (1.0 vs 2.6 years, P < 0.0001) and had longer hospitalizations (4 vs 3 days, P = 0.005). There was no difference in the proportion of VP-SE cases with a coinfection diagnosis compared to NVP-SE (25.8% vs 19.9%, P = 0.42). Controlling for age and history of hospitalization for a neurological condition, intensive care unit (ICU) admission had a stronger association with coinfection (aOR 2.52 (95%CI 1.78-3.57)) than having VP-SE (aOR 1.41 (0.66-3.01)). Groups had similar SE recurrence rates at 12-months (12.9% VP vs 16.9% NVP, P = 0.56) and reduced vaccine uptake following initial SE (from 93.5% to 56.3%).

Conclusion: Proportionally few first SE cases were VP-SE, with higher ICU admission rates mostly explained by younger age and higher coinfection rates. Vaccination plans are needed to improve vaccine uptake following SE.