Examination of anomalous self-experience in first-episode psychosis: interrater reliability

Abstract

Background: The growing research focus on early detection of schizophrenia has fostered an increasing interest in the nonpsychotic experiential anomalies that may antedate schizophrenia spectrum disorders and assist early differential diagnosis. The Examination of Anomalous Self-Experience (EASE) is a phenomenologically inspired checklist, specifically designed to support the comprehensive assessment of these characteristic subjective experiences.

Aim: To assess the interrater reliability of the EASE.

Sampling and methods: Twenty-five first-episode psychosis (FEP) patients were interviewed with the EASE. Videotaped interviews were blindly reevaluated. Internal consistency, overall interrater correlation and item interrater agreement (Cohen's kappa) were estimated.

Results: The EASE showed good to excellent internal consistency across the two raters (Cronbach's alpha above 0.87) and an overall inter-rater correlation above 0.80 (Spearman's rho, p < 0.001). The average kappa of the EASE was 0.65, ranging from 0.51 to 0.73 over the 5 domains; kappa values at an item level were very good in 9 items, good in 20 items, moderate in 11 items and fair in 4 items.

Conclusion: The EASE provides a reliable and internally consistent clinical tool for the assessment of subjective experience in FEP patients, suggesting that this instrument could usefully supplement standard clinical assessments during the onset phase of psychosis.