The Epilepsy‐Cog study: Methods to establish a harmonized study of late onset epilepsy in a metacohort of six population‐based cohorts in the United States
Hyunmi Choi, Jose Gutierrez, Tian Wang, Minghua Liu, Cheng‐Shiun Leu, Sylwia Misiewicz, Jiying Han, Natalie Bello, Mary L. Biggs, Emily M. Briceño, Adam M. Brickman, James F. Burke, Ligong Chen, Lisandro D. Colantonio, Stefany P. Diaz Andino, Mitchell S. V. Elkind, Annette L. Fitzpatrick, Christopher Gonzalez Corona, Rebecca F. Gottesman, Alden L. Gross, Lei Huang, Emily L. Johnson, W. Craig Johnson, Deborah A. Levine, W. T. Longstreth, Sofia Pelagalli Maia, Richard P. Mayeux, Brian C. Petersen, Oluwadamilola Obalana, Dolly Reyes‐Dumeyer, Tatjana Rundek, Danurys Sanchez, Steven J. Shea, Kevin Strobino, Carolyn W. Zhu, Evan L. ThackerAbstract
Objective
With the expected demographic shift toward those ≥65 years of age in the United States, late onset epilepsy (LOE) poses a significant public health issue, yet it has been historically understudied. We are undertaking an effort in the Epilepsy‐Cog study to pool individual participant data from six United States‐based prospective cohort studies. In this paper, we outline the process for ascertaining epilepsy, harmonizing, and pooling individual participant data across the six cohorts.
Methods
The Epilepsy‐Cog study includes individual participant data from six United States‐based longitudinal cohort studies: Atherosclerosis Risk in Communities Study, Cardiovascular Health Study, Multi‐Ethnic Study of Atherosclerosis, Northern Manhattan Study (NOMAS), Reasons for Geographic and Racial Differences in Stroke, and Washington Heights/Inwood Columbia Aging Project. In all cohorts except NOMAS, prevalent and incident epilepsy were ascertained using Medicare claims‐based algorithms. In NOMAS, epilepsy cases were identified through cohort‐based reporting and medical record review. To perform cross‐cohort harmonization of variables, we used the lowest common denominator approach, assigning response categories or value levels in common across all cohorts.
Results
From a total of 68 544 participants across six cohorts, 43 753 participants met eligibility criteria for Epilepsy‐Cog. Among them, we identified 551 (1.3%) participants with prevalent epilepsy and 1500 (3.4%) participants with incident epilepsy. We have harmonized demographic characteristics, health behaviors, vascular risk factors (VRFs), one genetic variable, medication use, subjective health status measures, incident events, and cause‐of‐death variables.
Significance
The Epilepsy‐Cog pooled cohort of 43 753 participants with and without epilepsy, combined with harmonized demographic, VRF, and event data, offers a unique resource to yield new insights into LOE.