Improving the reliability of the diagnosis of post-traumatic stress disorder in civil litigation

Post-traumatic stress disorder (PTSD) has become one of the most frequently diagnosed psychiatric disorders, although there is little evidence that PTSD can be reliably diagnosed using an unstructured clinical interview. There are reports, however, of reasonable agreement in the diagnosis of the disorder between clinicians using structured interviews. PTSD is unusual in the inclusion of a necessary cause for the disorder in the A, or stressor criteria, which can lead expert witnesses in civil cases to pre-empt the court by deciding the cause of the patients' condition. Removing the A criterion in the diagnostic criteria for PTSD in DSM-V, or at least excluding opinion about the A criterion from expert evidence, would separate the diagnosis of PTSD from judgements about its aetiology.