Quality of life in major depressive disorder: the role of pain and pain catastrophizing cognition

Abstract

Objective

Pain symptoms are frequent complaints in patients with major depressive disorder (MDD). Although it is known that pain intensity and pain-related cognition predict quality of life (QOL) in patients with chronic pain, limited studies have examined their roles in MDD. The study aimed to determine whether pain and pain catastrophizing were independent predictors of QOL in MDD after accounting for the impact of anxiety and depression.

Methods

This is a prospective, naturalistic follow-up study. Ninety-one Chinese patients were enrolled during an acute episode of MDD, 82 of them were reassessed 3 months later using the same assessment on pain, anxiety, depression, and QOL. Pain intensity was evaluated using a verbal rating scale and a visual analog scale. Quality of life was assessed using the 36-item Short Form Health Survey. Pain-related cognition was assessed at baseline with the Pain Catastrophizing Scale.

Results

There was significant improvement in pain, anxiety, depression, and QOL from baseline to 3-month follow-up. Hierarchical regression analyses showed that pain intensity was significantly associated with QOL at baseline and 3 months. Pain complaint was more important than anxiety and depressive symptoms in predicting changes in both physical and psychosocial domains of QOL. After controlling for the severity of pain, anxiety, and depression, Pain Catastrophizing Scale score was independently associated with QOL in MDD.

Conclusion

The study supports the specific role of pain and pain-related cognition in predicting QOL in depressed patients. Further studies targeting pain-related cognition for improving the outcome of MDD are necessary.

Introduction

Major depressive disorder (MDD) is currently the leading cause of disability in developed countries and the fourth leading cause of disability worldwide. Projections estimate that MDD will rise to be the second leading cause of disability worldwide by the year 2020 [1], [2]. One of the most disabling aspects of MDD is its adverse impact on quality of life (QOL). Previous studies have shown that patients with MDD have significantly impaired QOL compared with healthy individuals and people with chronic medical conditions [3], [4]. Multiple factors are associated with the QOL in patients with MDD, including the age of onset and severity of depression, psychiatric and medical comorbidity, pain and somatic symptoms, and sociodemographic characteristics [5], [6], [7], [8]. Acute pharmacotherapy of depression can improve psychosocial functioning and QOL, but a significant disability persists despite symptom improvement [9].

Pain symptoms are frequent complaints in patients with MDD. A recent review reported an average 65% co-occurrence rate for pain and depression [10]. The severity of pain complaints in MDD was found to predict a longer time to remission, poorer clinical outcome, greater functional impairment, worse QOL, and higher associated health care costs [11]. Clinical studies suggest that pain symptoms in MDD could be a somewhat separate entity from depressive symptoms [12], [13]. Whereas depressive symptoms continued to improve over time, pain symptoms had minimal change after some initial improvements [14].

Psychological factors are important in shaping the experience of chronic pain; in particular, the manner in which one copes with pain is a consistent predictor of clinical outcome. Of the pain-related coping variables that have been studied, pain catastrophizing has been found to have one of the strongest associations with negative pain outcomes [15], [16]. The construct of catastrophizing incorporates magnification of pain symptoms, rumination about pain, feelings of helplessness, and pessimism about pain-related outcomes [17]. It is proposed that pain catastrophizing promotes fear of movement and injury, in turn, leads to avoidance behavior, disuse, disability, and depression. Recent studies have found that pain catastrophizing has significant associations with disability and QOL in patients with chronic pain, even after controlling for levels of anxiety, depression, and pain [18], [19], [20], [21].

Understanding pain catastrophizing's contribution to QOL is important for developing and improving treatments in patients with MDD associated with pain symptoms. Previous studies have shown that after remission of depression, functioning levels in patients with a previous depressive episode are still substantially lower than those in healthy controls [22], [23]. If pain catastrophizing is found to contribute significantly to physical and psychosocial functioning, we would expect that treatments targeting depressive symptoms alone might be insufficient for improving QOL in patients with MDD and that interventions specifically designed to target pain catastrophizing would be beneficial. The present study was designed to determine the relationship of pain catastrophizing with QOL in patients with MDD after accounting for the impact of pain, depression, and anxiety. We also examined if the effects of pain catastrophizing differed across domains of QOL.