Validation of a brief screening instrument for the ascertainment of epilepsy

Epilepsia. 2010 Feb;51(2):191-7. doi: 10.1111/j.1528-1167.2009.02274.x. Epub 2009 Aug 19.


Purpose: To validate a brief screening instrument for identifying people with epilepsy in epidemiologic or genetic studies.

Methods: We designed a nine-question screening instrument for epilepsy and administered it by telephone to individuals with medical record-documented epilepsy (lifetime history of >or=2 unprovoked seizures, n = 168) or isolated unprovoked seizure (n = 54), and individuals who were seizure-free on medical record review (n = 120), from a population-based study using Rochester Epidemiology Project resources. Interviewers were blinded to record-review findings.

Results: Sensitivity (the proportion of individuals who screened positive among affected individuals) was 96% for epilepsy and 87% for isolated unprovoked seizure. The false positive rate (FPR, the proportion who screened positive among seizure-free individuals) was 7%. The estimated positive predictive value (PPV) for epilepsy was 23%, assuming a lifetime prevalence of 2% in the population. Use of only a single question asking whether the subject had ever had epilepsy or a seizure disorder resulted in sensitivity 76%, FPR 0.8%, and estimated PPV 66%. Subjects with epilepsy were more likely to screen positive with this question if they were diagnosed after 1964 or continued to have seizures for at least 5 years after diagnosis.

Discussion: Given its high sensitivity, our instrument may be useful for the first stage of screening for epilepsy; however, the PPV of 23% suggests that only about one in four screen-positive individuals will be truly affected. Screening with a single question asking about epilepsy yields a higher PPV but lower sensitivity, and screen-positive subjects may be biased toward more severe epilepsy.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • Aged
  • Electroencephalography
  • Epilepsy / diagnosis*
  • Epilepsy / epidemiology
  • False Positive Reactions
  • Female
  • Humans
  • Interviews as Topic
  • Male
  • Medical Records
  • Middle Aged
  • Minnesota / epidemiology
  • Predictive Value of Tests
  • Prevalence
  • Psychometrics
  • Reproducibility of Results
  • Risk Factors
  • Seizures / diagnosis*
  • Seizures / epidemiology
  • Sensitivity and Specificity
  • Surveys and Questionnaires*
  • Urban Population / statistics & numerical data