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

Abstract

Objective: Recent studies have revealed a heterogeneous prevalence and presentation of PTSD 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 (IES-R).

Methods: Data were collected from 1,000 employees of a large hospital during the COVID-19 pandemic and were further subjected to item response theory (IRT) analysis with respect to the discrimination (a) and difficulty (b) parameters of the item pool.

Results: Our results demonstrated that the IES-R items had a good discriminative ability (a) and covered a range of distress severity (b) associated with traumatic experiences. The IES-R was found to be a reliable and informative instrument for assessing individuals with moderate to severe trauma-related distress across the spectrum of traumatic symptoms. In particular, items #10 ("jumpy or easily startled") and #6 (" thought about it when didn't mean to"), reflecting the PTSD domains of hyperarousal and intrusion, excelled in discriminating between different levels of traumatic distress. Conversely, items related to avoidance and sleep disturbance showed diminished discriminative ability.

Conclusions: The item analysis of the IES-R may be used to assess trauma symptoms in the context of a traumatic exposure, thereby identifying the most discriminative and informative items of the PTSD measure in our context. Our findings may refine the IES-R and facilitate the development of a more effective scale with optimized item parameters.