Positive and Negative Relationship between Anxiety and Depression of Patients in Pain: A Bifactor Model Analysis

Jingdan Xie,Yebing Yang,Qian Bi,Danmin Miao,Wen Shang,Huiming Zhang,Wen Li,Ming Yan,Jerson Laks

doi:10.1371/journal.pone.0047577

Abstract

BackgroundThe relationship between anxiety and depression in pain patients has not been clarified comprehensively. Previous research has identified a common factor in anxiety and depression, which may explain why depression and anxiety are strongly correlated. However, the specific clinical features of anxiety and depression seem to pull in opposite directions.ObjectiveThe purpose of this study is to develop a statistical model of depression and anxiety, based on data from pain patients using Hospital Anxiety and Depression Scale (HADS). This model should account for the positive correlation between depression and anxiety in terms of a general factor and also demonstrate a latent negative correlation between the specific factors underlying depression and anxiety.MethodsThe anxiety and depression symptoms of pain patients were evaluated using the HADS and the severity of their pain was assessed with the visual analogue scale (VAS). We developed a hierarchical model of the data using an IRT method called bifactor analysis. In addition, we tested this hierarchical model with model fit comparisons with unidimensional, bidimensional, and tridimensional models. The correlations among anxiety, depression, and pain severity were compared, based on both the bidimensional model and our hierarchical model.ResultsThe bidimensional model analysis found that there was a large positive correlation between anxiety and depression (r = 0.638), and both scores were significantly positively correlated with pain severity. After extracting general factor of distress using bifactor analysis, the specific factors underlying anxiety and depression were weakly but significantly negatively correlated (r = −0.245) and only the general factor was significantly correlated with pain severity. Compared with the three first-order models, the bifactor hierarchical model had the best model fit.ConclusionOur results support the hypothesis that apart from distress, anxiety and depression are inversely correlated. This finding has not been convincingly demonstrated in previous research.

Highlights

Pain often co-occurs with negative psychological moods, especially depression and anxiety
The anxiety and depression symptoms of pain patients were evaluated using the Hospital Anxiety and Depression Scale (HADS) and the severity of their pain was assessed with the visual analogue scale (VAS)
We developed a hierarchical model of the data using an Item Response Theory (IRT) method called bifactor analysis

Summary

Introduction

Pain often co-occurs with negative psychological moods, especially depression and anxiety. Arnold et al [1] found that depression and anxiety were alleviated to a certain extent while treating fibromyalgia with pregabalin, and the change in pain showed a low to moderate positive correlation with the change in depression and anxiety. Numerous studies have shown a relatively high correlation between these psychological symptoms. Bossala et al [3] found that the correlation of anxiety and depression reached 0.77 among patients with chronic hemodialysis. The relationship between anxiety and depression in pain patients has not been clarified comprehensively. Previous research has identified a common factor in anxiety and depression, which may explain why depression and anxiety are strongly correlated. The specific clinical features of anxiety and depression seem to pull in opposite directions

Methods

Results

Conclusion