Abstracts

Rationale: Understanding the long-term outcomes of newly diagnosed epilepsy (NDE) is paramount for formulating treatment strategies and for patients counseling. Differences in methodology and seizure freedom (SF) measures used in different studies have contributed to a wide variation in reported outcomes. It is unclear how these SF measures compare against one another and in different onset age groups, and whether the outcomes have changed over time. A systematic review and meta-analysis of NDE cohorts will allow exploration of the heterogeneity of results, an estimate of pooled effect size for various outcomes and a clearer insight and breakdown of the existing evidence.

Methods: Observational studies of children and adults with NDE and >12 month follow-up providing clear definitions of seizure freedom outcomes were selected by two independent reviewers from a search of PubMed and EMBASE databases between 1/1/1995 and 1/1/2021. Primary outcomes were cumulative 1-year SF, 1-year terminal remission (1YRTR) and 5-year terminal remission(5YRTR). Secondary outcomes included the pooled proportion of patients with early sustained remission, the proportion of patients in remission off anti-seizure medications (ASMs) at end-follow-up, and the incident proportion of drug resistant epilepsy according to ILAE criteria. Random-effects meta-analysis was used to estimate pooled proportions and between study heterogeneity was assessed by I² and Cochran’s Q.

Results: 32 cohorts (total 15,321 patients; 45.3% female) were included and classified into either adult, children or mixed age subgroups. Cumulative 1-year SF estimate was 80% (95% confidence [CI] 75 – 84%). Terminal remission for at least 1 and 5 years were 69% (95% CI 64 –74) and 69% (95% CI 62 – 76%) respectively. High heterogeneity was observed in all primary outcomes with an I² of >90%. Across age subgroups, children showed a higher 1YRTR (75% vs 61% p = 0.010) as well as cumulative SF compared to adults (85% vs 72% p=0.014), whilst there were not enough subgroup studies to allow comparisons for 5YRTR. Early sustained SF occurred in more than one-third of all NDE patients (36%, 95% CI 29 – 44%), whilst up to 40% (95% CI 30 – 50%) of NDE patients were eventually off ASMs at end follow-up. There is a paucity of ILAE based drug-resistance outcomes in NDE with an overall effect size of 14% (95% CI - 11 – 17%) reported across five studies. There was no association of publication year or earliest date of cohort recruitment with the main primary outcomes.

Conclusions: Current estimates on SF in NDE population show reliability in the context of this random-effects meta-analysis which incorporated worldwide studies for a diverse population estimate. Higher cumulative SF relative to terminal remission as well as comparatively lower early sustained remission suggest a fluctuating course in newly diagnosed epilepsy is not uncommon. More robust measures of remission (5YRTR) showed equivalence to briefer remission periods (1YRTR) at end follow-up. SF outcomes have not improved despite the availability of more ASMs.

Funding: Please list any funding that was received in support of this abstract.: Monash University RTP Stipend scholarship.