Pain Interference Mediates the Relationship Between Severe Pain and Depression in Patients with Chronic Pain Referred from Primary Care.

Abstract

Objectives: This study aimed to evaluate the prevalence of depression and its relationship with clinical characteristics, demographics, and pain intensity in patients experiencing uncontrolled chronic pain. It also examined whether severe pain interference with daily activities mediates the connection between severe pain and depression.

Design: This cross-sectional observational study used data from 2,081 adult patients referred from primary care to a tertiary hospital.

Data source: Depression was assessed using the Depression subscale of the Hospital Anxiety and Depression Scale (HADS-D), with scores of 11 or higher indicating depression. Sociodemographic and clinical characteristics were collected, and pain severity and interference were evaluated with the Brief Pain Inventory (BPI).

Analysis: Poisson regression assessed the associations between depression and demographic/clinical factors. Mediation analysis examined the effect of severe interference on the relationship between severe pain and depression.

Results: Depression was found in 42.7% of patients. Those with depression reported a higher prevalence of severe pain (61% vs. 43%) and more significant interference with daily activities (81% vs. 42%). Males (PR = 0.73, 95% CI: 0.64-0.83) and patients aged 60 years or older (PR = 0.73, 95% CI: 0.64-0.83) exhibited a lower prevalence of depression. Widespread pain (PR = 1.29, 95% CI: 1.15-1.44) and severe pain (PR = 1.39, 95% CI: 1.24-1.53) were associated with a higher prevalence of depression. When severe interference was included in the regression model, the association with severe pain diminished, and severe interference emerged as a stronger predictor of depression (PR = 2.60, 95% CI: 2.24-3.02). In the mediation analysis, severe interference mediated the relationship between severe pain and depression.

Conclusion: Depression is common among patients with uncontrolled chronic pain and is linked to significant pain and functional impairment. Addressing these functional limitations is essential for managing this population.