Subjective and Objective Measures of Dryness Symptoms in Primary Sjögren's Syndrome - Capturing the discrepancy

BACKGROUND: There is a weak relationship between subjective symptoms and objective markers of disease activity in individuals with Primary Sjögren's Syndrome (PSS). This presents a significant barrier to developing treatments if modifying disease markers does not translate into reduced perception of symptoms. Little is known about the reasons for this discrepancy. OBJECTIVES: To develop a novel method for capturing the discrepancy between objective tests and subjective dryness symptoms (a 'Sensitivity' scale) and to explore predictors of dryness Sensitivity. METHODS: Archive data from the UK Primary Sjogren's Syndrome Registry (n=681) was used. Patients were classified on a scale from -5 (stoical) to +5 (sensitive) depending on the degree of discrepancy between their objective and subjective symptoms classes. Sensitivity scores were correlated with demographic variables, disease-related factors and symptoms of pain, fatigue, anxiety and depression. RESULTS: Patients were on average relatively stoical for both dryness symptoms (ocular mean±s.d. -0.42±2.2, oral mean±s.d. -1.24±1.6). Twenty-seven percent of patients were classified 'sensitive' to ocular dryness in contrast to 9% for oral dryness. Hierarchical regression analyses identified the strongest predictor of ocular dryness was self-reported pain and the strongest predictor of oral dryness was self-reported fatigue. CONCLUSIONS: Ocular and oral dryness sensitivity can be classified on a continuous scale. The two symptom types are predicted by different variables. A large number of factors remain to be explored that may impact on symptom-sensitivity in PSS and the proposed method could be used to identify relatively sensitive and stoical patients for future studies. This article is protected by copyright. All rights reserved.