Symptoms of depression and anxiety as unique predictors of pain-related outcomes following burn injury

Background: The adverse consequences of burn injuries include pain and psychological distress, which show bidirectional associations. However, much of the existing research has relied on global measures of distress that do not separate distinct symptoms of anxiety and depression. Purpose: The purpose is to assess the prospective effects of anxiety and depression on pain and functional outcomes following burn injury. Methods: This article describes a 2-year cohort study in patients hospitalized for serious burn injuries (assessments at discharge and 6-month, 1-year, and 2-year follow-up). Linear mixed effects analyses were conducted to model anxiety and depression's unique longitudinal effects; at each time point, depressive and anxiety symptoms were studied as predictors of subsequent changes in pain, fatigue, and physical function. Results: When studied in separate prediction models, both depression and anxiety were strong prospective predictors of greater pain, more fatigue, and physical dysfunction at the subsequent time point (ps <.01). However, when both were included in a single model to study their unique effects, depressive symptoms (but not anxiety) emerged as a significant predictor of subsequent increases in pain and reductions in physical functioning, whereas anxiety (but not depression) predicted subsequent elevations in fatigue. Conclusions: These findings suggest potentially distinct effects of depression and anxiety and imply that assessment and early treatment of both depressive and anxiety symptoms may help improve a broad range of long-term pain-related outcomes following burn injury.