UCSF

Background: Veterans with chronic non-cancer pain (CNCP) are a vulnerable population whose care remains a challenge for clinicians, policymakers, and researchers. For many of these veterans, the use of long-term opioid therapy (LTOT) to manage CNCP has steadily decreased while stricter opioid prescribing guidelines have increased in response to the “opioid epidemic”. Purpose: The aims of this study were to 1) adapt Gatchel and colleagues’ biopsychosocial model to study CNCP in the veteran population, 2) review current evidence on the effectiveness of LTOT for improving pain and physical functioning in veterans, 3) investigate the trajectories of pain, opioid dosage, and physical functioning among veterans prescribed LTOT and 4) examine whether these trajectories differ by sociodemographic characteristics (i.e., age, marital status, employment, living situation), and mood (anxiety and depression). Methods: This study identified physical, psychological, and social factors that contribute to CNCP in veterans and reviewed 12 studies out of 474 articles on the effectiveness and safety of opioids prescribed longer than 3 months in the veteran population. This study also analyzed data from a randomized clinical trial that compared opioid prescribing practices (liberal versus conservative dosing) in 134 veterans for 12 months in an outpatient VA pain clinic. To examine pain intensity and opioid use for longer-term, additional 24-month data were collected retrospectively on veterans who remained on LTOT. Regression models were used to test change over time in the later 24 months of follow-up for pain intensity and opioid use (log-transformed). Second, the effects of sociodemographic characteristics were tested in the first 12 months only, since these characteristics were not collected in the later years after the original RCT analysis. Results: The Biopsychosocial Model of CNCP in Veterans described the most prevalent biological pain conditions (e.g., musculoskeletal disorders, osteoarthritis, low back pain, headaches, polytrauma, chronic post-surgical pain, traumatic brain injury, neuropathy, and amputation), psychological stressors (e.g., post-traumatic stress disorder, depression, anxiety, substance abuse), and social factors (e.g., homelessness, social isolation, disability, decreased access to medical care). The current literature does not demonstrate strong evidence to support the effectiveness of LTOT for improving pain intensity and physical functioning in veterans prescribed opioids over a 12-month period for CNCP. This study found that pain intensity and prescribed opioid dosage did not significantly change in the later 24 months of follow-up among veterans with CNCP but there was a significant increase in their physical functioning during the 12-month period (p<0.05). In the multivariate model, an increase in depression scores was associated with an increase in pain intensity (β=0.06, P=0.003) and physical disability (β=1.48, P<0.0001) for veterans prescribed LTOT for CNCP. Conclusion: The biopsychosocial model of CNCP for veterans is a useful and relevant conceptual framework to guide clinical care and future research for LTOT. The literature review indicated the paucity of evidence supporting the use of LTOT for improving pain and physical functioning and over 12 months. The findings of this study described the relative stability of pain intensity, physical functioning, and opioid dosage in veteran with CNCP. In addition, depression plays an important role in the management of veterans with CNCP and highlight the need of concurrent management of both conditions.