Although posttraumatic stress disorder (PTSD) is common following traumatic brain injury (TBI; Greer et al., 2020), the complex association between these conditions requires further explication. Data repositories, such as FITBIR, which is the product of a national effort to compile individual participant-level TBI data from multiple studies into a unified database, provide a useful avenue for exploring the PTSD-TBI relationship. The present project is a proof-of-concept study demonstrating the ability to harmonize data from numerous shared studies to better understand comorbid PTSD following TBI.
We searched for, merged, and harmonized data from studies with TBI and PTSD variables to analyze rates of probable PTSD across TBI severity categories. The methods and code used to extract, clean, standardize, and harmonize the data have been publicly shared and as additional studies are contributed to FITBIR, they will be added to these meta-datasets.
After harmonizing key variables across FITBIR datasets, the final sample consisted of 1633 participants. Approximately 79% of participants across studies had a history of mild TBI (mTBI) and 32-37% screened positive for PTSD. Those with mTBI had 2.8 greater odds of screening positive for PTSD compared to those with no TBI (95% CI: 1.90, 3.90).
Study findings show that unifying patient-level data is possible and can contribute to knowledge of complex medical and psychiatric comorbidity. These methods allow for nuanced analyses addressing diversity, equity, and inclusion issues often left out of single studies due to small sample sizes of minoritized groups within individual studies.

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