Psychometric evaluation and development of a 3-item short form of the Posttraumatic Growth Inventory (PTGI-3): A National Institute on Disability, Independent Living, and Rehabilitation Research Burn Model System Study.

The Posttraumatic Growth Inventory (PTGI) was developed to measure positive psychological changes individuals can experience after trauma. While the 10-item form (PTGI-10) is relatively brief, an even shorter version would be valuable in situations where participant response burden is of particular concern. The PTGI-10 was administered to 1,076 adults recovering from moderate to severe burn injury between 6-months and 20-years after injury as part of an ongoing longitudinal study. Analyses completed to inform item selection included classical test theory analyses of reliability (i.e. Cronbach's alpha) and item performance, item response theory analyses, and qualitative item review. A focus group selected items for a new short form while considering results of the analyses as well as item content and acceptability. Score agreement between the PTGI-10 and the newly created short form was examined. A confirmatory factor analysis supported unidimensionality though reliability (α=0.94) and results of local dependency indicated items were highly redundant. A new three item short form (PTGI-3) was created and includes one item from each of the three categories of perceived benefits identified in posttraumatic growth theory. Reliability of the new short form is moderate (>0.8) for scores ±1 SD around the mean. Scores on the PTGI-3 correlate highly (r=0.94) with scores on the PTGI-10. The PTGI-3 has sufficient reliability for group comparisons, balances item content, and includes items that are acceptable to people with burn injury.