Do the EULAR Sjögren's syndrome outcome measures correlate with health status in primary Sjögren's syndrome?

Abstract

Objective: This study sets out to investigate the relationship between health status [EuroQol five-dimensions questionnaire (EQ-5D)] in primary SS and three of the European League Against Rheumatism (EULAR) SS outcome measures-the disease activity index (ESSDAI), the patient reported index (ESSPRI) and the sicca score. In particular, the goal was to establish whether there is a relationship between the EULAR outcome measures and quality of life.

Methods: Health status was evaluated using a standardized measure developed by the EuroQol Group-the EQ5D. This permits calculation of two measures of health status: time trade-off (TTO) values and the EQ-5D visual analogue scale (VAS) scores. We used Spearman's rank correlation analysis to investigate the strength of association between health status and three EULAR measures of physician- and patient-reported disease activity in 639 patients from the UK primary SS registry (UKPSSR) cohort.

Results: This study demonstrates that the EULAR SS disease-specific outcome measures are significantly correlated with health outcome values (P < 0.001). Higher scores on the ESSDAI, EULAR sicca score and ESSPRI are associated with poorer health states-i.e. lower TTO values and lower VAS scores. While all three are significantly correlated with TTO values and EQ-5D VAS scores, the effect is strongest for the ESSPRI.

Conclusion: This study provides further evidence supporting the use of ESSDAI, EULAR sicca score and ESSPRI measures in the clinic. We also discuss the need for disease-specific measures of health status and their comparison with standardized health outcome measures.

Keywords: disease activity; outcome measures; patient-reported outcomes; primary Sjögren’s syndrome; quality of life; utility values.