Objective: The goal of this study was to examine the relative importance of global affective distress, self-report of depressive symptoms, and presence or absence of major depression to the experience of chronic pain.
Setting: A multidisciplinary pain program at a university medical center was the setting for this study.
Patients: Subjects in this study were 211 consecutive patients with chronic pain.
Outcome measures: Pain duration, compensation, and litigation status were controlled for in the statistical analyses, as each correlated significantly with at least one of the measures of affect. Global affective distress was assessed using the Global Severity Index (GSI) from the Brief Symptom Inventory. The Beck Depression Inventory and the Center for Epidemiological Studies Depression Scale were used as measures of self-report of depressive symptoms. Presence or absence of major depression was based on DSM-IV criteria.
Results and conclusions: The GSI, Beck Depression Inventory, and Center for Epidemiological Studies Depression Scale were significantly correlated with each measure of the experience of pain, although clinical depression was only significantly related to self-reported disability and negative thoughts about pain. The self-report measures of depression maintained their relation to the dependent measures when the somatic items from the scales were removed, suggesting that the relations were not spuriously due to the influence of pain symptoms on the scales. When examining the unique contribution of each variable to the experience of pain (by simultaneously controlling for the other measures of affect), the GSI was uniquely related to the sensory and affective components of pain. Self-report of depressive symptoms was more highly related to a measure of the evaluative component of pain and uniquely related to self-reported disability and negative thoughts about pain. The results are discussed within the context of theoretical models of the relation between pain and affect, and suggestions for future research are presented.