The association of probable PTSD at baseline and pain-related outcomes after chronic pain rehabilitation: A comparison of DSM-5 and ICD-11 criteria for PTSD

Background There is a high prevalence of posttraumatic stress disorder (PTSD) in patients with chronic pain. However, different patients are identified depending on the diagnostic system used. Moreover, it is unclear if the conceptualizations of PTSD are differently associated with outcomes of pain rehabilitation. Hence, the aims of the present study were first to explore the prevalence rates and diagnostic agreement of probable PTSD according to the ICD-11 and the DSM-5 screening tools (International Trauma Questionnaire [ITQ] vs. PTSD Checklist [PCL-5]), and secondly, to explore the associations of probable PTSD determined by ITQ and PCL-5 with psychological distress measures at baseline, and thirdly, the associations with pain and disability after pain rehabilitation adjusting for psychological covariates. Methods A consecutive cohort of patients with chronic non-malignant pain (n = 152) referred to a Danish interdisciplinary pain center was assessed at baseline prior to their first visit and at follow-up three days after completed treatment. Results The estimated probable PTSD baseline prevalence rates were 15.8% (ITQ) and 16.4% (PCL-5). However, the diagnostic agreement between the PCL-5 and the ITQ was only moderate (k = 0.64). Overall, compared to the ITQ probable PTSD according to the PCL-5 correlated more strongly with psychological distress. Only the ITQ was associated with poorer outcomes after rehabilitation, explaining alone 7-8% of the variance in disability and pain intensity adjusted for covariates. Conclusions The results underline the importance of taking the conceptualization and assessment of PTSD into consideration when investigating the impact of PTSD on pain rehabilitation. Significance There is a high prevalence of probable PTSD in patients with chronic pain. However, different patients with probable PTSD are identified depending on the diagnostic system used. Although similar probable PTSD prevalence rates (about 16%) were found using DSM-5 and ICD-11 PTSD screening tools (PCL-5 and ITQ, respectively), the diagnostic agreement between the systems was only moderate (k = 0.64). At the same time, only probable PTSD estimated according to the ITQ and not the PCL-5 was a significant predictor of disability after pain rehabilitation.