Differentiating pain-related distress from depression in people with persistent musculoskeletal pain: a mixed methods study

Depressive symptoms are commonly experienced by people with persistent musculoskeletal (MSK) pain. There is evidence for some individuals that this may be best characterised as pain-related distress; a reaction to living with the impact of pain, rather than a depressive illness. No explorations exist of how to differentiate between these in primary care. This study aimed to explore key factors that may differentiate between pain-related distress and depression, and the effectiveness of existing symptom screening tools (Patient Health Questionnaire-9 [PHQ-9] and 4-Dimensional Symptom Questionnaire [4DSQ]) in identifying distress through a mixed methods approach. First, 21 general practitioners and 21 people with pain were interviewed about their experiences of pain-related distress. Second, 597 primary care patients with MSK pain completed a cross-sectional questionnaire study reporting on their pain, mental health symptoms, and other life events. Qualitative data suggested key factors distinguishing between pain-related distress and depression included general positive outlook, physical function, and acceptance. Quantitative findings showed that the PHQ-9 may overcategorise participants as depressed; of the 207 participants classified as distressed (but not depressed) on the 4DSQ, 118 (57%) were categorised as moderately or severely depressed on the PHQ-9. Lower positive outlook and sleep interference scores, and higher PHQ-9 and perceived stress scores significantly predicted participants experiencing distress only compared with distress and depression, matching the qualitative findings. These findings indicate that differentiation between pain-related distress and depression may be possible in primary care consultations for persistent musculoskeletal pain. This is essential to ensure that patients are offered appropriate, acceptable, and effective management.