Abstract 7: Psychometric Assessment of the Impact of Event Scale-Revised Among Zambian Women with Cervical Cancer

Abstract Purpose: Zambia has the third-highest incidence of cervical cancer (CC) globally. CC is the most common cancer among Zambian women. A cancer diagnosis impacts mental health which in turn affects cancer treatment and outcomes. However, mental health research and validated scales is limited in Zambia, especially for women with CC. The study objective aims to evaluate the psychometric properties of the Impact of Event Scale-Revised (IES-R) among women newly diagnosed with CC. Methods: We enrolled Zambian women newly diagnosed with CC between August–October 2024 at the Cancer Diseases Hospital in Lusaka, Zambia. In-person and phone interviews were conducted by trained research staff using a structured questionnaire. The IES-R, a 22-item scale previously validated in multiple countries, was used to measure posttraumatic stress disorder (PTSD) and 3-subdomains (Intrusion, Avoidance, and Hyperarousal). Confirmatory Factor Analysis via Structural Equation Modeling was used to assess unidimensionality of IES-R items. McDonald’s Omega was used to assess the reliability of the IES-R and subdomains. The PROMIS-57, a validated scale measuring quality of life within 9-domains, was used to assess convergent and divergent validity of the IES-R. Results: Included were 199 women, aged between 24–88 years. The reliability of the IES-R and subdomains were excellent, with coefficient omegas for overall PTSD (ω=.95) and subdomains: Intrusion (ω=.86), Avoidance (ω=.87), and Hyperarousal (ω=.88). The IES-R showed excellent convergent and divergent validity with PROMIS-57 domains. For each PROMIS-57 domain, Spearman’s Rho correlation of IES-R was convergent with anxiety (ρ=.74), depression (ρ=.72), fatigue (ρ=.70), sleep disturbances (ρ=.70), and pain interference (ρ=.73) and divergent with physical function (ρ=-.61) and social wellbeing (ρ=-.60). Similar patterns were observed for IES-R subdomains. Factor loadings for the IES-R were unidimensional, ranging from .35 to .92 except items “Pictures about it popped into my mind” (.15) and “I had dreams about it” (.02). Coefficient alphas were between .94 to .95 across all IES-R items. The mean of IES-R was 55.8 with a 98% prevalence of PTSD. Conclusion: The IES-R showed excellent psychometric properties among Zambian women newly diagnosed with CC supporting its continued use for research in this population. Low factor loadings for items 9 and 20 from IES-R may reflect the interview timing, conducted immediately after diagnosis. Citation Format: Douglas DeMoulin, Linda Malulu-Chiwele, Violet Kayamba, Wilbroad Mutale, Perfect Shankalala, Xiao-Ou Shu, Choolwe Jacobs. Psychometric Assessment of the Impact of Event Scale-Revised Among Zambian Women with Cervical Cancer [abstract]. In: Proceedings of the 13th Annual Symposium on Global Cancer Research; 2025 Sep 16. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2025;34(12_Suppl):Abstract nr 7.