Recent studies suggest that depression is associated with somatic pain. Despite growing research interest in the topic, the effects of depression-related somatic pain remain unclear. The present study sought to investigate the relationships between depression-related somatic pain, treatment satisfaction, and functions of daily living, and to compare them with the relationships between these factors and mental health measures.

We administered an Internet-based survey to 663 patients with depression in Japan, including questions about pain symptoms, mental health, functions of daily living, and dissatisfaction with depression treatment. The SF-8 questionnaire was used to assess functions of daily living. We conducted a multiple linear regression analysis to examine the associations between depression-related somatic pain, functions of daily living and treatment satisfaction, and between mental health measures, somatic pain and functions of daily living.

An increase per unit in the number of pain symptoms was associated with a 1.04-unit decrease in physical functioning score (P < 0.001), a 0.67-unit decrease in the role functioning-physical score (P < 0.001), and a 0.53-unit decrease in role functioning-emotional score (P = 0.0010). Meanwhile, we found no significant association between the number of pain symptoms and patients’ satisfaction with treatment, and no significant association between the number of pain symptoms and social functioning.

These results suggest that even when patients report satisfaction with their treatment, they may be suffering from reduced physical functioning and role functioning. These impairments may escape clinical recognition when clinicians or patients fail to discuss pain symptoms.