Item-wise validity study of the Impact of Event Scale-Revised: self-reported reactions of hospital personnel exposed to a stressful workplace.

Objective: Recent studies have revealed a heterogeneous prevalence and presentation of post-traumatic stress disorder across countries. It is crucial to assess the methodological and item-level measurement factors that contribute to variations in mental disorder rates across cultures. This study aimed to investigate the traumatic experiences of hospital workers by employing item analysis of the Impact of Event Scale-Revised.

Methods: Data were collected from 1,000 employees of a large hospital during the coronavirus disease 2019 pandemic and were analyzed according to item response theory analysis regarding item pool discrimination (a) and difficulty (b) parameters.

Results: The Impact of Event Scale-Revised items had good discriminative ability (a) and covered a range of distress severity (b) associated with traumatic experiences. According to our results, the Impact of Event Scale-Revised is a reliable and informative instrument for assessing individuals with moderate to severe trauma-related distress across the spectrum of trauma symptoms. In particular, items 10 ("jumpy or easily startled") and 6 ("I thought about it when I didn't mean to") reflected the post-traumatic stress disorder domains of hyperarousal and intrusion and excelled in discriminating between different levels of post-traumatic distress. Conversely, items related to avoidance and sleep disturbance showed lower discriminative ability.

Conclusions: Item analysis of the Impact of Event Scale-Revised may be used to assess trauma symptoms in the context of a trauma exposure, identifying the most discriminative and informative items for measuring post-traumatic stress disorder in our context. Our findings may help refine the Impact of Event Scale-Revised and facilitate the development of a more effective scale with optimized item parameters.