Depression and pain impair daily functioning and quality of life in patients with major depressive disorder

Abstract

Background

Depression and pain frequently occur together. The objective of this study was to investigate the effects of depression and pain on the impairment of daily functioning and quality of life (QOL) of depressed patients.

Methods

We enrolled 131 acutely ill inpatients with major depressive disorder. Depression, pain, and daily functioning were assessed using the 17-item Hamilton Depression Rating Scale, the Short-Form 36 (SF-36) Body Pain Index, and the Work and Social Adjustment Scale. Health-related QOL was assessed using three primary domains of the SF-36: social functioning, vitality, and general health perceptions. Pearson׳s correlation and structural equation modeling were used to examine relationships among the study variables. Five models were proposed.

Results

In all, 129 patients completed all the measures. Model 5, both depression and pain impaired daily functioning and QOL, was the most fitted structural equation model (χ²=9.2, df=8, p=0.33, GFI=0.98, AGFI=0.94, TLI=0.99, CFI=0.99, RMSEA=0.03). The correlation between pain and depression was weak (r=−0.27, z=−2.95, p=0.003).

Limitation

This was a cross-sectional study with a small sample size.

Conclusion

Depression and pain exert a direct influence on the impairment of daily functioning and QOL of depressed patients; this impairment could be expected regardless of increased pain, depression, or both pain and depression. Pain had a somewhat separate entity from depression.

Introduction

Depression and pain frequently occur together. An international study (Simon et al., 1999) demonstrated that somatic symptoms occurred in 69% of patients with major depressive disorder (MDD) at a primary care center. Most of the somatic symptoms were pain-related. In another study of 150 depressed inpatients, (Corruble and Guelfi, 2000) 92% reported at least one pain symptom, and 76% complained of the presence of multiple pain symptoms.

According to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), (APA, 1994) pain is not a diagnostic symptom in MDD. Pain complaints are included only as associated features. Furthermore, pain is less or not emphasized in standard measures of depression severity, such as the 17-item Hamilton Rating Scale for Depression (HAMD-17) (Hamilton, 1960) and the Montgomery-Asberg Depression Rating Scale (Montgomery and Asberg, 1979). However, a growing body of evidence suggests that pain and depression may operate within similar areas of the brain that regulate both mood and the affective components of pain (Giesecke et al., 2005). Some of the overlap between depression and pain can be explained biologically, in that pain and depression appear to share common pathways and neurotransmitters (Bair et al., 2003, Fields, 2000).

The nature of the relationship between depression and pain is still inconclusive. Some research indicates that there is a causal relationship between the two (Fishbain et al., 1997). Others suggest that depression and pain are indistinguishable and that chronic pain is really a form of depression (Blumer and Heilbronn, 1982).

Three theories have been postulated to explain the relationship between pain and depression (Bair et al., 2003, Lepine and Briley, 2004). The first theory suggests that pain is caused by depression (Larson et al., 2004, Leino and Magni, 1993, Magni et al., 1994, Pine et al., 1996). The second theory proposes that depression is caused by pain (Dohrenwend et al., 1999, Nicassio and Wallston, 1992, Patten, 2001). The third theory suggests that depression and pain may interact bidirectionally (Gureje, 2007, Hotopf et al., 1998, Von Korff and Simon, 1996).

A common definition of quality of life (QOL) focuses overall satisfaction with life and general sense of personal well-being (Spilker, 1990). Depression scales, such as HAMD-17, do not cover important domains of QOL. QOL measurement can capture differences, not shown in HAMD-17. QOL assessment made it possible to compare the impact of different conditions (e.g., depression symptoms and pain) (De Fruyt and Demyttenaere, 2009). MDD is associated with impairment of daily functioning and quality of life (QOL) (APA, 2010, Greer et al., 2010, Pyne et al., 1997, Rapaport et al., 2005, Trivedi et al., 2006). Therefore, the APA (APA, 2010) guideline suggests that a complete psychiatric assessment should include daily functioning and QOL. Besides depression, pain also has negative effects on a patient׳s daily functioning and QOL (Gureje et al., 1998, Husain et al., 2007, Lepine and Briley, 2004, Mavandadi et al., 2007, Ohayon and Schatzberg, 2010, Smith et al., 2001, Sullivan et al., 2001). Depressed patients with pain have been reported to be associated with poor depression outcomes, including more severe depression, poorer QOL, and daily functioning (Demyttenaere et al., 2006, Gambassi, 2009, Lee et al., 2009, Lin et al., 2003, Munoz et al., 2005, Ohayon and Schatzberg, 2010, Von Korff et al., 1992). Pain patients with MDD have poor QOL than those without depression (Elliott et al., 2003). As mentioned above, pain and depression are considered to have overlapping underlying mechanisms. The different level of impairment in daily function and QOL contributed by depressive symptoms, pain, or depressive symptoms plus pain should be investigated. However, most previous studies that examined a single issue and its effect on patients׳ QOL or daily functioning may not have been sufficient to test a number of inter-related problems simultaneously. Structural equation modeling (SEM) can offer a framework to investigate the relationship among several variables simultaneously. SEM contains modeling of causal relationships among variables, examination of direct and indirect effects, modeling of variables as latent or measured, and testing of competing models (Bollen, 1989, Kline, 2011).

The goal of this study was to construct a set of viable models using SEM to examine the relationships between depression, pain, daily functioning, and QOL for hospitalized patients with MDD.