Content validation using Aiken methodology through expert judgment of the first Spanish version of the Eppendorf Schizophrenia Inventory (ESI) in Peru: A brief qualitative report.

Background: The main objective of this study was the validation through the expert judgment of the first Spanish version of the Eppendorf Schizophrenia Inventory (ESI-Sp).

Materials And Methods: A translation and cultural adaptation procedure as a first stage was carried out, which was evaluated by four psychiatrists with clinical experience. In a second stage, we recruited a group of clinical psychiatrists to evaluate the translated instrument by judging the items' clarity and relevance. Content validity was performed using the Aiken methodology (Aiken's V).

Results: For the first stage, we did not find any items that needed alteration during translation and adaptation. Concerning the raters' stage, 30 clinical psychiatrists (47.07±13.62 years) completed the rating of the ESI-Sp. Of them, the majority worked in an institute (10/30; 33.33%) and had "15 or more" years of experience (12/30; 40.00%). The null hypothesis was rejected for all items and demonstrated the content validity of each item. Similar results were found for the factors of the ESI. Finally, the total Aiken's V for the ESI did not include the values of the null hypothesis in the confidence intervals (V=0.78; CI95 [0.70; 0.85]), demonstrating content validity.

Conclusions: ESI-Sp is a valid and representative instrument to determine subjective experiences in patients with a high risk of schizophrenia. The construct validation of the ESI-Sp is pending, which our research group will carry out after this first step.