Table 1.

PICOS criteria for inclusion and exclusion of studies

PICOS	Inclusion	Exclusion
Population	Patients with LGS, including clearly defined “probable” LGS	Other DEEs
Intervention	Studies assessing the overall burden of illness of LGS without the impact of an intervention	Studies assessing the impact of interventionsa
Comparator	N/A	–
Outcomes	Prevalence/incidence Economic burden Direct and indirect costs Resource use Patient and caregiver HRQoL and broader patient-reported outcomes Mortality	–
Study designs/publication type	Publications reporting original data, including: Healthcare insurance claims data Chart reviews Registry studies Electronic healthcare databases studies Epidemiologic surveys Observational studies Economic evaluations if they contain original data on resource utilisation and HRQoL	In vitro and in vivo studies Preclinical studies Case reports and case series Clinical studies reporting only efficacy and safety data Economic evaluations reporting on specific interventionsb Reviewsc, SLRsc, comments, letters, editorials and press releases
Limits	Searches of conferences in Embase were limited to the previous 3 years (conferences 2018-current)d	None

HRQoL, health-related quality of life; LGS, Lennox–Gastaut syndrome; N/A, non-applicable; SLR, systematic literature review

^aThe focus is on the overall burden as opposed to the impact of specific interventions

^bEconomic evaluations reporting on specific interventions without any original data on e.g HRQoL (utilities) and healthcare resource utilisation will be excluded, however, the reference lists will be searched to ensure all relevant studies are captured in this SLR.

^cReviews and SLRs will be excluded from final inclusion but the reference lists will be searched to ensure all relevant studies are captured in this SLR.

^dThe rationale for excluding conference abstracts > 3 years is that this should be sufficient time for the data to be published in peer-review journals if they are of sufficient importance and quality. The rationale for including conference abstracts ≤3 years is to include the most up-to-date data.