“There are important reasons to study chronic pain and PTSD together,” says Matthew J. Bair, MD, MS. Chronic pain and PTSD co-occur frequently. This comorbidity leads to significant adverse effects for patients, and their co-occurrence is worse for patients with only one of these conditions. The comorbidity has negative additive effects on pain and PTSD symptoms, including pain intensity, pain-related disability, worse quality of life, depression, and anxiety, all of which may complicate treatment.”

In a study published in Pain Medicine, Dr. Bair and colleagues aimed to compare pain and psychological outcomes in veterans with chronic musculoskeletal pain and comorbid PTSD, or pain alone, in order to determine if veterans with the comorbidity respond differently to a stepped-up intervention than those with pain alone.

Usual Care Vs Stepped Care

Dr. Bair and colleagues analyzed data from the Evaluation of Stepped Care for Chronic Pain (ESCAPE) trial at six Veterans Health Affairs clinics, using a cohort of 222 veterans who served in Iraq and Afghanistan. A longitudinal analysis of veterans with chronic musculoskeletal pain and PTSD, or pain alone, was conducted and included available baseline and 9-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 of 41 or greater at baseline.

Findings demonstrated statistically significant differences and worse outcomes on pain severity, pain cognition, and psychological symptoms in veterans with comorbid pain and PTSD compared with those with pain alone. Significant differences emerged for pain catastrophizing, depression, and anxiety. The interaction between PTSD and the stepped-care intervention was not significant.

Patients With Pain + PTSD Utilize More Healthcare

“When chronic pain and PTSD co-occur, a patient’s experience of their pain and PTSD is worse than if only one is present,” Dr. Bair says. “With the combination of pain and PTSD, patients have more frequent and severe pain and psychological symptoms. Due to the additive negative effects of comorbidity, patients with pain and PTSD are more difficult to manage than patients with a single condition.”

The study found that veterans’ PTSD status at baseline was not independently associated with change in disability, interference, severity, pain centrality, or self-efficacy (Table). “On the other hand, PTSD was independently associated with change scores at follow-up for catastrophizing, depression, and anxiety,” Dr. Bair notes. “We hypothesized that veterans with chronic pain and PTSD would not respond as well to the ESCAPE trial intervention, but this differential treatment response was not supported.”

Mean change scores and effect sizes in pain and psychological outcomes in the PTSD and non-PTSD groups were also observed, according to Dr. Bair. “There were differences between the pain plus PTSD groups and pain alone groups in terms of how pain outcome scores changed during the clinical trial,” he says. “However, these differences in scores did not reach statistical significance. The magnitude of change in these pain and psychological outcomes varied. There were medium effects for both groups for pain disability, severity, and interference and small effects for pain centrality, self-efficacy, catastrophizing, depression, and anxiety. Across both groups, we observed that effect sizes were medium.”

Application to Non-Veterans

While VA studies often carry the caveat that findings may not generalize to non-veteran patients, “Previous studies in civilian samples show this frequent overlap, which suggests findings from this study can apply to non-veteran/civilians,” says Dr. Bair. “Given the high co-prevalence, associated costs, and additive adverse effects, we need more effective treatment of this common comorbidity in both veteran and non-veteran patients.”

Dr. Bair and colleagues concur that more research on models that integrate treatment for chronic pain with treatment for PTSD are needed. “Right now, treatment is fairly ‘siloed,’ or fragmented, where pain is usually treated by primary care and pain specialists and PTSD is treated in primary care and mental health settings,” he notes.  “The overlapping setting for both is primary care. Therefore, I’d like to see the development of integrated treatments or care models that simultaneously manage pain and PTSD in primary care.”