The incidence and prevalence of drug resistant epilepsy: a systematic review and meta-analysis

Objective: In order to evaluate the incidence and prevalence of
drug-resistant epilepsy (DRE) as well as its predictors and correlates, we
conducted a systematic review and meta-analysis of observational studies.
Methods: Our protocol was registered with PROSPERO and the PRISMA and
MOOSE reporting standards were followed. We searched MEDLINE, Embase, and
Web of Science. We used a double arcsine transformation and random-effects
models to carry out our meta-analyses. We performed random-effects
meta-regressions using study-level data. Results: Our search strategy
identified 10,794 abstracts. Of these, 103 articles met our eligibility
criteria. There was high inter-study heterogeneity and risk of bias. The
cumulative incidence of DRE was 25.0 % (95% CI: 16.8, 34.3) in child
studies but 14.6% (95% CI: 8.8, 21.6) in adult/mixed ages studies. The
prevalence of DRE was 13.7% (95% CI: 9.2, 19.0) in
population/community-based populations but 36.3% (95% CI: 30.4, 42.4) in
clinic-based cohorts. Meta-regression confirmed that the prevalence of DRE
was higher in clinic-based populations and in focal epilepsy. Multiple
predictors and correlates of DRE were identified. The most reported of
these were having a neurological deficit, an abnormal EEG, and symptomatic
epilepsy. The most reported genetic predictors of DRE were polymorphisms
of the ABCB1 gene. Conclusions: Our observations provide a basis for
estimating the incidence and prevalence of DRE, which vary between
populations. We identified numerous putative DRE predictors and
correlates. These findings are important to plan epilepsy services,
including epilepsy surgery, a crucial treatment option for people with
disabling seizures and DRE.