Interpreting change on the neurobehavioral symptom inventory and the PTSD checklist in military personnel

Objective: The purpose of this study was to examine the prevalence and stability of symptom reporting in a healthy military sample and to develop reliable change indices for two commonly used self-report measures in the military health care system. Participants and method: Participants were 215 U.S. active duty service members recruited from Fort Bragg, NC as normal controls as part of a larger study. Participants completed the Neurobehavioral Symptom Inventory (NSI) and Posttraumatic Checklist (PCL) twice, separated by approximately 30days. Results: Depending on the endorsement level used (i.e. ratings of mild' or greater vs. ratings of moderate' or greater), approximately 2-15% of this sample met DSM-IV symptom criteria for Postconcussional Disorder across time points, while 1-6% met DSM-IV symptom criteria for Posttraumatic Stress Disorder. Effect sizes for change from Time 1 to Time 2 on individual symptoms were small (Cohen's d=.01 to .13). The test-retest reliability for the NSI total score was r=.78 and the PCL score was r=.70. An eight-point change in symptom reporting represented reliable change on the NSI total score, with a seven-point change needed on the PCL. Conclusions: Postconcussion-like symptoms are not unique to mild TBI and are commonly reported in a healthy soldier sample. It is important for clinicians to use normative data when evaluating a service member or veteran and when evaluating the likelihood that a change in symptom reporting is reliable and clinically meaningful.