A temporary spike: Investigating Lennox-Gastaut syndrome incidence in the US following FDA approval of cannabidiol.

OBJECTIVE: In June 2018, the US Food and Drug Administration (FDA) approved pharmaceutical grade cannabidiol (CBD; Epidiolex®) for the treatment of seizures associated with Lennox-Gastaut syndrome (LGS). We sought to examine whether the FDA approval of CBD was associated with changes in LGS diagnostic practices in the United States. METHODS: We computed the annual number of new LGS diagnoses in the United States from 2017 to 2023 using a large, population-based database of electronic health records. RESULTS: We identified a temporary increase in the number of new LGS diagnoses in 2019: the incidence rate rose by roughly 30% from 2018 to 2019, and almost 60% from 2017 to 2019, before it returned to pre-FDA CBD approval baseline (2020-2023). SIGNIFICANCE: This temporary increase occurred in temporal proximity to the 2018 FDA approval of CBD for LGS. While causality cannot be inferred, this descriptive finding may reflect a confluence of factors including patient-caregiver interest and clinician practices to gain access to CBD. Clinician practices may have involved applying/updating LGS ICD codes to patients previously diagnosed with LGS and misdiagnosing patients with severe epilepsies as LGS. These findings underscore the clinical and research importance of appropriately using the LGS ICD code and ensuring accurate, reliable diagnosis of LGS based on standardized, well-defined criteria. Nevertheless, given this work's reliance on administrative data, readers should interpret results cautiously, as misclassification and inconsistent coding practices can influence epidemiologic estimates and research conclusions.