Pain and Psychological Outcomes Among Iraq and Afghanistan Veterans with Chronic Pain and PTSD: ESCAPE Trial Longitudinal Results.

Objective: To compare pain and psychological outcomes in veterans with chronic musculoskeletal pain and comorbid post-traumatic stress disorder (PTSD) or pain alone and to determine if veterans with comorbidity respond differently to a stepped-care intervention than those with pain alone.

Design: Secondary analysis of data from the Evaluation of Stepped Care for Chronic Pain (ESCAPE) trial.

Setting: Six Veterans Health Affairs clinics.

Subjects: Iraq and Afghanistan veterans (N = 222) with chronic musculoskeletal pain.

Methods: Longitudinal analysis of veterans with chronic musculoskeletal pain and PTSD or pain alone and available baseline and nine-month trial data. Participants randomized to either usual care or a stepped-care intervention were analyzed. The pain-PTSD comorbidity group screened positive for PTSD and had a PTSD Checklist-Civilian score ≥41 at baseline.

Results: T tests demonstrated statistically significant differences and worse outcomes on pain severity, pain cognitions, and psychological outcomes in veterans with comorbid pain and PTSD compared with those with pain alone. Analysis of covariance (ANCOVA) modeling change scores from baseline to nine months indicated no statistically significant differences, controlling for PTSD, on pain severity, pain centrality, or pain self-efficacy. Significant differences emerged for pain catastrophizing (t = 3.10, P < 0.01), depression (t = 3.39, P < 0.001), and anxiety (t = 3.80, P < 0.001). The interaction between PTSD and the stepped-care intervention was not significant.

Conclusions: Veterans with the pain-PTSD comorbidity demonstrated worse pain and psychological outcomes than those with chronic pain alone. These findings indicate a more intense chronic pain experience for veterans when PTSD co-occurs with pain. PTSD did not lead to a differential response to a stepped-care intervention.