1157 — Comorbid Chronic Pain and PTSD among Iraq and Afghanistan Veterans: Longitudinal Analysis of Pain and Psychological Outcomes

Outcalt SD, Center for Health Information & Communication, Department of Veterans Affairs, Veterans Health Administration, HSR&D CIN 13-416, Roudebush VAMC; Ang D, Rheumatology & Immunology, Wake Forest School of Medicine; Wu J, Biostatistics, Indiana University School of Medicine; Yu Z, Biostatistics, Indiana University School of Medicine; Bair MJ, Center for Health Information & Communication, Department of Veterans Affairs, Veterans Health Administration, HSR&D CIN 13-416, Roudebush VAMC;

Objectives:
To examine longitudinal pain and psychological outcomes among OEF/OIF/OND Veterans with chronic pain and comorbid PTSD.

Methods:
We analyzed longitudinal data from the ESCAPE randomized clinical trial. Interviews with 222 Veterans with three or more months of musculoskeletal pain were conducted at baseline and 9 months after randomization. Analyses examined pain severity, disability, interference, and psychological outcomes. Comparison groups were categorized by PCL-C score of 41, a minimum score to meet DSM-IV PTSD criteria.

Results:
At baseline, Veterans with PTSD had greater pain severity (71.6 vs. 63.4 on GCPS), disability (16.1 vs. 13.0 on Roland), interference (6.9 vs. 4.7 on BPI), catastrophizing (29.0 vs. 18.3 on PCS), centrality (32.2 vs. 25.3 on CPS), lower pain self-efficacy (4.4 vs. 6.0 on ASES), higher depression (16.1 vs. 8.8 on PHQ-9 ) and anxiety (13.6 vs. 6.6 on GAD-7; all p < .0001). These differences persisted at 9 months (pain severity: 63.6 vs. 55.7; disability: 13.9 vs. 10.1; interference: 5.5 vs. 3.5; catastrophizing: 24.8 vs. 13.7; centrality: 33.7 vs. 28.2; self-efficacy: 5.1 vs. 6.3; depression: 14.1 vs. 7.4; anxiety: 12.2 vs. 5.7; all p < .0001-.01). Adjusting for baseline values and demographic covariates, we compared baseline-9 month change scores: Veterans without PTSD improved more than those with PTSD on catastrophizing (F(1) = 9.6, p = .002), depression (F(1) = 11.5, p = .0008), and anxiety (F(1) = 14.5, p = .0002). Marginally significant differences emerged for disability and interference but no significant differences on pain severity, centrality, or self-efficacy.

Implications:
OEF/OIF/OND Veterans in a stepped care trial for chronic pain demonstrated worse overall pain and psychological outcomes at baseline and 9 months when PTSD co-occurred. Consistent with hypotheses, Veterans without PTSD improved significantly more over time on pain catastrophizing, depression, and anxiety; signals of this effect emerged for pain disability and interference. These findings suggest a more intense and disabling chronic pain experience that may differentially respond to treatment among newly returning Veterans with comorbid PTSD.

Impacts:
These results contribute to our understanding of the relationship between chronic pain and PTSD, two highly prevalent conditions within VHA. Our findings emphasize the combined adverse effects of this comorbidity and highlight the importance of evaluating and treating PTSD to maximize treatment response for chronic pain.