Measuring psychological trauma after spinal cord injury: Development and psychometric characteristics of the SCI-QOL Psychological Trauma item bank and short form

OBJECTIVE To describe the development and psychometric properties of the SCI-QOL Psychological Trauma item bank and short form. DESIGN Using a mixed-methods design, we developed and tested a Psychological Trauma item bank with patient and provider focus groups, cognitive interviews, and item response theory based analytic approaches, including tests of model fit, differential item functioning (DIF) and precision. SETTING We tested a 31-item pool at several medical institutions across the United States, including the University of Michigan, Kessler Foundation, Rehabilitation Institute of Chicago, the University of Washington, Craig Hospital and the James J. Peters/Bronx Veterans Administration hospital. PARTICIPANTS A total of 716 individuals with SCI completed the trauma items RESULTS The 31 items fit a unidimensional model (CFI=0.952; RMSEA=0.061) and demonstrated good precision (theta range between 0.6 and 2.5). Nine items demonstrated negligible DIF with little impact on score estimates. The final calibrated item bank contains 19 items CONCLUSION The SCI-QOL Psychological Trauma item bank is a psychometrically robust measurement tool from which a short form and a computer adaptive test (CAT) version are available.