Translation, cross-cultural adaptation, and validation of the Bulgarian version of the Liverpool Adverse Event Profile

Background: Adverse effects (AEs) of antiepileptic drugs (AEDs) affect the quality of life of patients with epilepsy and their outcomes. There are no questionnaires or studies on the reliability and validity of instruments measuring AEs of AEDs in patients with epilepsy in Bulgarian language. Purpose: The aim of the present study was the translation, cross-cultural adaptation, and validation of the LAEP in the Bulgarian language in order to use it in the Bulgarian-speaking population in providing a reliable instrument for the clinical monitoring of patients with epilepsy. Methods: One hundred thirty-one patients (57 men and 74 women, mean age: 40.13. ±. 13.37. years) took part in the investigation. The internal consistency and test-retest reliability were tested by Cronbach's α and ICC estimations. The convergent construct validity was tested by estimating the correlation of the LAEP-BG with the QOLIE-89 and the discriminant validity by evaluating the difference between LAEP-BG scores and clinical parameters such as the type of epilepsy using Kruskal-Wallis ANOVA. Results: The LAEP-BG showed high internal consistency and reliability. The Cronbach's α of the total scale was 0.86. No significant differences between the Cronbach's α coefficients of the total LAEP-BG and original English, Chinese, Spanish, Korean, and Portuguese-Brazilian versions of the questionnaire were observed. The ICCs, which evaluate the test-retest reliability, were higher than the recommended value of 0.75 and determined the strong positive correlations between the first and second examinations. The creation of two subscales "Neurological and psychiatric side effects" and "Non neurological side effects" of the LAEP-BG proposed by us showed good internal consistency (Cronbach's α of 0.85 and 0.71, respectively). The LAEP-BG scores significantly correlated with other questionnaires such as the Quality of Life in Epilepsy Inventory-89 (QOLIE-89) and showed a good discriminative validity between groups with different levels of self-assessed AEs of AEDs. Conclusion: The Bulgarian version of the Liverpool Adverse Event Profile (LAEP) is a reliable and valid tool in assessing the patient-reported AEs of AEDs and their impact on the patient's outcome.