Presence and predictors of pain in depression: results from the FINDER study.

BACKGROUND Patients with depression often experience pain. There is limited understanding of the relation between pain and other symptoms (depressive, anxious and non-painful somatic symptoms). This exploratory study assesses pain severity and interference of pain with functioning in a clinically depressed population and investigates the relation between the different groups of symptoms. METHODS FINDER was a 6-month prospective, observational study investigating health-related quality of life of outpatients with depression initiating antidepressant treatment. Patients completed ratings on the Hospital Anxiety and Depression Scale (HADS), Somatic Symptom Inventory (SSI-28), and overall pain severity and interference of pain with functioning using Visual Analogue Scales (VAS) at baseline and at 3 and 6 months. Regression analyses identified factors associated with overall pain severity and interference of pain with functioning, at baseline and over the observation period. RESULTS Of 3468 eligible patients at baseline, 56.3% experienced moderate to severe pain and 53.6% had moderate to severe pain-related interference with functioning. At 6 months of follow-up, these proportions decreased to 32.5% and 28.1%, respectively. Higher baseline SSI-somatic scores (non-painful) were strongly associated with greater pain severity and greater pain-related interference with functioning at baseline and over 6 months. Certain socio-demographic (increasing age, being unemployed) and depression-related factors (more previous episodes, longer duration of current episode) were also significantly associated with greater pain severity and interference over 6 months, while higher baseline severity of depression (HADS-D) and further education were associated with less severe pain or pain-related interference with functioning over 6 months. CONCLUSIONS Over half of depressed patients in this study experienced moderate to severe pain. Painful somatic symptoms appear to be closely related to non-painful somatic symptoms, more than to depressive or anxious symptoms suggesting that painful and non-painful somatic symptoms can be considered as one group of 'somatic symptoms,' all of them associated with depressive and anxious symptoms.