Pain in primary Sjögren's syndrome: the role of catastrophizing and negative illness perceptions.

OBJECTIVES: Pain is a major factor in health quality in Sjögren's syndrome (SS), but little is known about the factors that contribute to pain severity. Because pain perception has been linked to catastrophizing in other diseases, we assessed subjects with primary SS (pSS) to explore a possible link between pain, illness appraisal, and catastrophizing. METHOD: A total of 92 subjects who met American-European consensus criteria for the diagnosis of pSS completed a questionnaire that included health history, medication use, illness perceptions, pain severity, mood, fatigue, pain anxiety, and pain catastrophizing. Linear regression was used to test the effect of each variable on pain severity. Multivariate models were constructed using backwards elimination to assess the significant predictors of pain severity. RESULTS: From linear regression analysis, catastrophizing was more strongly predictive of pain severity than age, fatigue, depression, or anxiety in both seropositive and seronegative pSS patients. In the multivariate model identified using backwards selection, four variables (pain catastrophizing, fibromyalgia status, serological status, and the conviction that illness would have severe consequences) predicted 55% of the variance in pain severity. CONCLUSIONS: Pain catastrophizing was a significant predictor of pain severity in both seropositive and seronegative pSS patients. This study suggests that behavioural interventions designed to reduce pain catastrophizing and negative appraisal of illness could be of benefit in pSS patients. Research is needed to test the effect of psycho-educational therapies on key patient-reported outcomes, particularly pain, depression, and fatigue, in pSS.

Oxidative stress and fatigue in systemic lupus erythematosus.

OBJECTIVE: The objective of this study is to investigate the relationship of oxidative stress to fatigue in systemic lupus erythematosus (SLE). METHODS: Patients with a confirmed diagnosis of SLE by ACR criteria and healthy controls completed validated questionnaires to assess depression and fatigue. Fatigue was measured with the Fatigue Severity Scale (FSS) and the Profile of Fatigue (Prof-F). Visual analogue scales (VAS) were also used to assess fatigue and pain. Depression was measured with the Center for Epidemiologic Studies Depression Scale (CES-D). Plasma F(2)-isoprostane was measured with gas chromatography/mass spectroscopy to assess oxidative stress. Evaluation included medical record review, physical exam and calculation of body mass index (BMI), disease activity (SLEDAI) and damage (SLICC) in the SLE patients. RESULTS: Seventy-one SLE patients with low disease activity (mean SLEDAI = 1.62 standard error (SE) 0.37, range 0-8) were compared to 51 controls. Fatigue-limiting physical activity (defined as FSS ≥ 4) was present in 56% of patients and 12% of controls. F(2)-isoprostane was higher in SLE patients with fatigue compared to not-fatigued SLE subjects (p = .0076) who were otherwise similar in ethnicity, disease activity and cardiovascular risk factors. Plasma F(2)-isoprostane was strongly correlated with FSS and Profile of Somatic Fatigue (Prof-S) (p < .0001), VAS fatigue (p = .005), CES-D (p = .008) and with BMI (p = .0001.) In a multivariate model, F(2)-isoprostane was a significant predictor of FSS after adjustment for age, BMI, pain and depression (p = .0002). CONCLUSION: Fatigue in SLE patients with low disease activity is associated with increased F(2)-isoprostane. F2-isoprostane could provide a useful biomarker to explore mitochondrial function and the regulation of oxidative pathways in patients with SLE in whom fatigue is a debilitating symptom.