The Development and Validation of the Global Post Trauma Symptom Scale-Uganda among Trauma-Affected Adults

The purpose of this study was to adapt and validate the Global Post-Traumatic Stress Scale (GPTSS) among adult caregivers of youth living with HIV in Uganda. This is the first study to adapt and validate a non-western instrument measuring post-traumatic symptoms in Uganda, which is critical in the accurate assessment of caregiver trauma on psychosocial functioning. The study utilized qualitative (i.e., cognitive interviews) and quantitative (e.g., classical test and item response theory) methods to establish content, criterion, and construct validity. The results indicated that the GPTSS was a valid and reliable assessment tool for the population. Specifically, cognitive interview results (n=31) indicated that participants broadly understood items of the GPTSS, but revisions in wording were needed to capture the intended meaning of some items. A reduced version of the GPTSS, GPTSS-U, was created through item response theory analyses based on discrimination criteria and difficulty parameters. A positive relationship between higher GPTSS-U and the PHQ-9 scores indicated acceptable criterion validity with a moderate effect size (r = 0.547; p < 0.000). Results from the graded response model indicated high discrimination parameters (range b = -.88, 3.14). Test information function curve findings indicated that the GPTSS is most precise at moderate to severe levels of post-traumatic symptoms. Using nested linear regression models, we found incremental validity as the total scores on the GPTSS-U significantly predicted functional impairment ( p < 0.05) beyond the impact of the Post Traumatic Stress Checklist-5. Overall findings indicate that post-traumatic symptom measures must be adapted and developed for cross-cultural use to maintain validity and contextual relevance.