A new head-to-head comparison of screening questionnaires for posttraumatic stress disorder (PTSD), published in The Lancet Psychiatry journal, shows a worrying discordance between the previous version of the PTSD definition in the Diagnostic and Statistical Manual of Mental Disorders - fourth edition (DSM-IV) and DSM-5, released in 2013 .The authors, led by Dr Charles Hoge of the Walter Reed Army Institute of Research, Silver Spring, Maryland, USA, found that just under a third (30%) of soldiers who screened positive for PTSD under the old DSM-IV criteria were excluded when DSM-5 criteria were used, and just under a quarter (20%) of those who met criteria under DSM-5 would not have been identified using the older DSM-IV criteria. The study is the first to directly compare the original DSM-IV and DSM-5 checklists in a large group of infantry soldiers.
During the revision process prior to the publication of DSM-5, the diagnosis of PTSD underwent many more changes than other mental disorder diagnoses affecting adults. The new definition of PTSD raises the number of symptoms from 17 to 20, and eight of the original 17 symptoms were substantially reworded. Dr Hoge's study surveyed 1822 US soldiers, 946 of whom had been deployed in Iraq and Afghanistan. They were administered an anonymous survey that included both of the self-reported DSM-IV and DSM-5 checklists.
The reclassification of PTSD also involved shifting the diagnosis from anxiety disorders to trauma and stress disorders, and included the recommendation that patients whose symptom pattern falls below the diagnostic threshold for PTSD be diagnosed with adjustment disorder, or an inability to adapt to stressful situations. This is concerning in the context of the US military, where that diagnosis carries a strongly pejorative connotation. Diagnosis of adjustment disorder can lead to administrative separation  and loss of benefits, which is of especial concern when those who would have been considered within the range of PTSD under the DSM-IV criteria could fall below the new threshold.
According to Dr Hoge, "After twelve years of war, and over 25 years of solid clinical and research experience with the previous definition, the reclassification of the PTSD diagnosis in DSM-5 presents concerns for the evaluation and treatment of service members and veterans who have served in Iraq and Afghanistan. Although we found that roughly the same percentage of soldiers met criteria for PTSD according to the two definitions, and the new PTSD screening tool was equivalent to the one we've used for many years, we also found that the two PTSD definitions did not identify the same individuals. The new definition also did not appear to have greater clinical utility than the previous one."*
Writing in a linked Comment, Professor Alexander McFarlane, at the Centre for Traumatic Stress Studies, University of Adelaide, Australia, said, "We think there should be a period of transition between legal use of DSM-IV and DSM-5 so that potential effects of these changes can be examined and that deserving individuals are not denied their legal rights. There is an obligation not to let this unintended consequence of a fashion of psychopathological formulation prevail."