Introduction Status epilepticus (SE) can be life-threatening in epilepsy. For some people however, SE is their first presentation of epilepsy and it is unclear whether their prognosis differs from people with pre-existing epilepsy and SE.

Methods Using the Secure Anonymised Information Linkage (SAIL) databank, we scrutinised primary care records in Wales for patients who have had an episode of SE. In order to better understand the prognosis of epilepsy following SE we looked at linked co-morbidity and mortality records.

Results Since 1991 there have been 2.9/100 000 episodes of SE recorded in Wales. 732 people were identified as having SE and there were 174 deaths recorded; 15.5% were within 6 months of SE. There were 13 potential cases of SUDEP. 12.8% of people who first presented in SE (and later died) had epilepsy as a cause of death compared to 3.1% of those who had pre-existing epilepsy prior to SE (p>0.02). Brain tumours were 2.5 times more people common in people with SE as their first presentation of epilepsy (n=10, 3.6%). More than seven times more people with epilepsy had a change of medication a month before SE (32%) than people who had SE without a history of epilepsy (4%; p>0.0001).

Discussion This nationwide informatics study has identified that SE as a first presentation of epilepsy is associated with an increased risk of SUDEP although not all cause mortality. We believe that SE occurring from pre-existing epilepsy may be triggered by poor medication concordance or a change in drug regimen, rather than a new symptomatic cause such as tumour or stroke.