Purpose: To validate the diagnosis of epilepsy in the Danish National Hospital Register.
Methods: We randomly selected 200 patients registered with epilepsy in the Danish National Hospital Register between 1977 and 2002 and validated the diagnosis according to the guidelines developed by the International League Against Epilepsy.
Results: We reviewed the medical records of 188 (94%) persons from 57 departments at 41 hospitals. The epilepsy diagnoses were confirmed in 153 patients, providing a positive predictive value for epilepsy of 81% (95% confidence interval (95% CI): 75-87%). Among the 35 patients who did not fulfill the criteria for epilepsy, 14 were admitted after a single, unprovoked seizure. Among patients registered with epilepsy the positive predictive value of seizure disorder was 89% (95% CI: 83-93%). Among patients classified with epilepsy syndromes, the positive predictive value for syndrome classification was 60% (95% CI: 44-74%) for epilepsy with complex focal seizures and 35% (95% CI: 22-51%) for primary generalized epilepsy.
Conclusion: The validity of the epilepsy diagnoses in the Danish National Hospital Register has a moderate to high positive predictive value for epilepsy, but a relatively low predictive value for epilepsy syndromes.