Table 2.

Candidate variables constructed from claims

Variable	Description
Suspected epilepsya
Primary epilepsy diagnosis	Epilepsy as a primary diagnosis
Epilepsy diagnosisb	Weighted; Epilepsy as primary, secondary, or tertiary diagnosis, and gives an additional weight to the occurrence of two or more primary codes 60 days apart
Algorithmic epilepsy diagnosis 1c	Any epilepsy diagnosis
Algorithmic epilepsy diagnosis 2c	Convulsions at least 30 days apart coinciding with inpatient stays, outpatient visits, or physician visits within one year
Potential false positivea
Withdrawal seizure	Diagnosis of seizure due to alcohol or drug withdrawal
Drug reaction seizure	Diagnosis of seizure due to a drug reaction
Syncope and collapse event	Diagnosis of “syncope or collapse”
Alteration of consciousness event	Diagnosis of alteration of consciousness event
Sleep disturbance event	Diagnosis of sleep disturbance event
Dementia	Diagnosis of dementia
Migraine event	Diagnosis of migraine event
Psychogenic event	Diagnosis of psychogenic event
Cerebrovascular event	Diagnosis of cerebrovascular event or cognitive deficit
Non-epileptic event diagnosis	Potential false positive diagnosis, excluding withdrawal and drug reaction seizures
Non-epileptic event or seizure diagnosis	Any potential false positive diagnosis
Specialty involvementd
Neurology	Epilepsy-related claim indicative of neurology specialty involvement
Site of cared
Urgent care and ER	Epilepsy-related claim indicative of service provided at an urgent care facility or hospital ER
Proceduree
Brain imaging	Epilepsy-related claim indicative of a brain imaging procedure
EEG	Epilepsy-related claim indicative of an EEG procedure
Treatment
Epilepsy-specific AED	Specific AED prescription (levetiracetam, lamotrigine, valproic acid, phenytoin, or carbamazepine) with a concurrent epilepsy diagnosis code
AEDb	All AED prescriptions

Abbreviations: ER = emergency room; EEG = electroencephalography; AED = antiepileptic drug; ICD-9 = International Classification of Diseases, Ninth Revision; CPT = current procedural terminology.

^aICD-9 codes

^bvariables used to recreate Holden et al algorithm¹

^cvariables created based on Faught et al. algorithm²

^dservice codes

^eCPT codes

List of variables constructed from ICD-9, CPT, and service codes for creation of models. Codes used to create each variable are listed in Supplemental Digital Content 2 (Table). Medicare claims were pulled between the dates 01/2012 and 12/2014.