Assessment and effect of a gap between new-onset epilepsy diagnosis and treatment in the US

Abstract

Objective: To estimate the treatment gap between a new epilepsy diagnosis and antiepileptic drug (AED) initiation in the United States.

Methods: Retrospective claims-based cohort study using Truven Health MarketScan databases (commercial and supplemental Medicare, calendar years 2010-2015; Medicaid, 2010-2014) and a validation study using PharMetrics Plus Database linked to LRx claims database (2009-2014). Persons met epilepsy diagnostic criteria, had an index date (first epilepsy diagnosis) with a preceding 2-year baseline (1 year for persons aged 1 to <2 years; none for persons <1 year), and continuous medical and pharmacy enrollment without epilepsy/seizure diagnosis or AED prescription during baseline. Outcomes included percentage of untreated persons (no AED prescription) up to 3 years' follow-up and comparative outcomes (incidence rate ratio: untreated persons/treated persons), including medical events and health care resource utilization.

Results: In the primary study, 59,970 persons met selection (or inclusion) criteria; 36.7% of persons with newly diagnosed epilepsy remained untreated up to 3 years after diagnosis. In the validation study (N = 30,890), 31.8% of persons remained untreated up to 3 years after diagnosis. Lack of AED treatment was associated with an adjusted incidence rate ratio (95% confidence interval) of 1.2 (1.2-1.3) for medical events, 2.3 (2.2-2.3) for hospitalizations, and 2.8 (2.7-2.9) for emergency department visits.

Conclusions: One-third of newly diagnosed persons remain untreated up to 3 years after epilepsy diagnosis. The increased risk of medical events and health care utilization highlights the consequences of delayed treatment after epilepsy diagnosis, which might be preventable.

Figure 1. Primary study: Kaplan-Meier estimate of time to antiepileptic drug treatment for persons with epilepsy

Population stratified by (A) sex, (B) payer type, (C) age group (0–4 years, 5–14 years, 15–24 years, 25–64 years, 65 + years), and (D) age (<17 years vs 17 years and older).

Figure 2. Primary study: Percentage of persons with epilepsy who were untreated, by epilepsy case definition

(A) Varying the number of ICD-9-CM codes from 2 to 4; (B) requiring ≥30 days between ICD-9-CM codes; (C) including only the first or principal epilepsy diagnosis; and (D) requiring ≥30 days between epilepsy codes and including only the first or principal diagnosis. ICD-9-CM = International Classification of Diseases, Ninth Revision, Clinical Modification.

Figure 3. Validation study: Kaplan-Meier estimate of time to antiepileptic drug treatment for persons with epilepsy

(A) Overall population (N = 30,890); and stratified by (B) age group (0–4 years, 5–14 years, 15–24 years, 25–64 years, 65+ years), and (C) age (<17 years vs 17 years and older). DF = degrees of freedom.