Abstracts

Rationale: Diagnostic delay may be associated with avoidable harm, and is likely most prominent when seizures are subtle. Using prospective data from The Human Epilepsy Project (HEP), which follows patients with newly diagnosed focal epilepsy, we examined the consequences of diagnostic delay in patients whose presentations were characterized by subtle seizures compared to disruptive seizures. Methods: We analyzed data from the first 175 participants enrolled between 2012-2015. Four were excluded due to incomplete enrollment data. Eligible patients (focal epilepsy seen within four months of treatment initiation) completed a seizure diary documenting all prior seizures. Using a standardized interview (DISCOVER) form, seizures were classified as either disruptive seizures (DS) (motor activity or verbal output, including generalized tonic-clonic seizures) or subtle seizures (SS) (primarily motor arrest or focal aware without motor) based on clinical descriptions. Time from onset to diagnosis was determined using seizure diaries and clinic notes. For uncertain dates, midpoint approximations were utilized for the closest week, month, or year. Parametric tests were used for normally distributed variables, and nonparametric tests for non-normally distributed variables. Results: Of 171 patients analyzed, 94 had initial presentations characterized by SS and 77 by DS. The groups had similar demographics (Table 1). Median time to diagnosis in patients with SS was 286 days (mean 1605.66 days) compared to 116 days (mean 302.87 days) in those with DS (p < 0.0001) (Figure 1). Of the 94 with SS, 61 patients (64.89%) experienced injury, motor vehicle accident (MVA), and/or a generalized tonic clonic seizure prior to treatment, 57 (60.64%) were not diagnosed until developing DS. Although patients with DS were more likely to have impaired awareness than patients with SS (p = 0.0013), the presence of impaired awareness did not impact time to diagnosis in either the DS (p = 0.3990) or SS (p = 0.3035) group. In the subgroup of 37 (39.4%) patients with subtle seizures who never developed DS, 18 (48.6%) had impaired awareness, which did not affect time to diagnosis (p = 0.1208). All potentially preventable MVAs (n = 5) occurred in patients with undiagnosed SS with impaired awareness. There was one unpreventable MVA due to a first lifetime seizure with secondary generalization. Conclusions: This study adds to growing evidence of lengthy delays in diagnosing focal epilepsy, and identifies a subset of these patients who not only experience the longest delays, but may also be responsible for the majority of preventable MVAs. This finding would support large-scale interventions aimed at improving recognition and reducing avoidable harm related to diagnostic delay in patients with epilepsy. Funding: There were no sources of funding for this study. The development of the HEP database comes from a variety of funding sources in industry, philanthropy, and foundations including The Epilepsy Study Consortium, UCB pharmaceuticals, Finding a Cure for Epilepsy and Seizures (FACES), Pfizer, Eisai, Lundbeck, Sunovion, The Andrews Foundation, The Vogelstein Foundation, Friends of FACES, and others.