Bidirectional Associations Between Pain and Perceived Stress Among Veterans: Depressive Disorder as a Predisposing Factor

Objective: Military veterans who were injured in combat very often report pain along with co-occurring perceived stress and preexisting depressive disorder. The systems model of pain is a theoretical model suggesting that pain and perceived stress are bidirectionally associated at the within-person level, and associations are heightened among those with depressive disorder. However, the systems model of pain has not been adequately tested. Testing the systems model of pain could illuminate salient treatment targets for combat-injured veterans with pain and co-occurring psychological problems. Methods: The present study empirically tests the systems model of pain among a sample of combat-injured veterans (N = 902) surveyed five times during an 18-month period. We used a multigroup, autoregressive latent trajectory with structured residual statistical model to test the within-person associations between pain and perceived stress and determine whether associations differ between veterans with and without a positive screen for depressive disorder. Results: In line with the systems model of pain, pain and perceived stress were bidirectionally associated only among combat-injured veterans with depressive disorder. Among such veterans, perceived stress was positively associated with subsequent pain (b = 0.12; 95% confidence interval = 0.06-0.17), and pain was positively associated with subsequent perceived stress (b = 0.44; 95% CI = 0.11-0.77). Conclusions: Our work highlights the interplay between pain and its psychological correlates among a particularly at-risk population. Clinicians addressing pain and perceived stress among combat-injured veterans should be prepared to identify and address depressive disorder.