Depression and trait-anxiety mediate the influence of clinical pain on health-related quality of life in fibromyalgia

Background: Fibromyalgia syndrome (FMS) is a chronic pain condition associated with a substantial decrease in health-related quality of life (HRQoL). This study investigated the relationships of HRQoL with clinical parameters of FMS (pain, insomnia and fatigue) and affective variables (depression and anxiety). Methods: Women with FMS (n =145) and healthy women (n = 94) completed the Short-Form Health Survey (SF36) to evaluate HRQoL, and self-report questionnaires pertaining to clinical pain, symptoms of anxiety and depression, fatigue and insomnia. Patterns of associations were assessed by correlation, multiple linear regression, and mediation analyses. Results: FMS patients showed lower scores on all SF-36 scales than healthy individuals. Clinical and emotional factors were inversely associated with SF-36 scores. Although depression was the strongest predictor of global HRQoL (explaining 36% of its variance), clinical pain and fatigue were the main predictors of physical components of HRQoL; depression and trait-anxiety were the main predictors of mental HRQoL components. Results of mediation analysis showed that depression, trait-anxiety and fatigue mediated the effect of clinical pain on HRQoL. Additionally, depression, trait-anxiety and fatigue mutually influenced each other, increasing their negative effects on the different areas of HRQoL. Limitations: Among all emotional factors, only anxiety and depression were considered. Conclusions: Our results suggest that FMS pain and related functional disability may increase depression and anxiety, in turn aggravating the primary symptoms of FMS and indirectly increasing the negative influence of pain on HRQoL. These results showed the need to evaluate and treat negative affective states in FMS.