Background Damage represents an important outcome parameter in systemic lupus erythematosus (SLE). Later in disease course it has a major impact on morbidity and mortality. Therefore, the assessment of damage in SLE is an important task. Most prior assessments are physician-reported but recent efforts try to establish patient-reported damage instruments (1, 3). Those are useful when frequent assessments are needed, e.g. in clinical studies, or if medical care is not timely available.
Objectives Lately we validated and evaluated the German version of the Brief Index of Lupus Damage (BILD). It showed a comparable validity to the original BILD with even higher correlation to physician-reported damage, even when used as a self-reported questionnaire (2). To further evaluate the construct validity of the instrument, we sought to examine it in a large observational cohort of SLE-patients.
Methods We used the LuLa-Study which is a longitudinal cross-sectional survey of the German LE self help community on a multitude of LE associated factors. It is being conducted annually by means of a self-reported questionnaire since 2001. In 2011 we included the German BILD; in 2009 we had included the SLICC/SDI to be completed by the attending physicians. To evaluate construct validity we examined disease-related outcomes and patient assessments. Additionally, we assessed the comparability of the BILD with the SLICC/SDI.
Results Despite a two year interval between the survey of the SLICC/SDI and BILD they still presented a moderately high correlation of r=0.581 (p < 0.001). Both damage scores showed comparable small to medium correlations with other patient assessments and outcomes.
As expected the BILD correlated moderately with the number of co-medications reflecting co-morbidities (r=0.477), physical functioning (r=-0.383) and to a lesser extent with disease activity (r=0.337) as well as duration, age, flares, fatigue and SF-12 MCS (all r<0.300). When regarding the BILD quartiles most assessments showed significant differences in univariate analysis with exception of the SF-12 MCS and the use of immunosuppressants. In multivariate analysis the number of co-medications, age, disease duration (all p<0.001), disease activity (p=0.020) and work disability (p=0.045) were predictive of higher BILD scores.
Conclusions The dependencies and predictors of the German BILD are comparable to the observations in our previous cohort (2), to the original BILD (1), as well as the LDIQ (patient reported ‘Lupus Damage Index Questionnaire’) (3) and the physician-based SLICC/SDI. It shows construct validity and therefore seems to be a useful and feasible patient-reported instrument to record damage in SLE.
Yazdany et al. Brief index of lupus damage: a patient-reported measure of damage in systemic lupus erythematosus. Arthritis care & research 2011; 63: 1170–1177.
Chehab et al. Validation and Evaluation of the German Brief Index of Lupus Damage (BILD) - a self-reported instrument to record damage in systemic lupus erythematosus. Submitted.
Costenbader KH, Khamashta M, Ruiz-Garcia S, et al. Development and initial validation of a self-assessed lupus organ damage instrument. Arthritis care & research 2010; 62: 559–568.
Acknowledgements The LuLa-study is supported by unrestricted grants from GlaxoSmithKline and UCB Pharma.
Disclosure of Interest None Declared