ASSOCIATION OF THE SYSTEMIC-LUPUS-INTERNATIONAL-COLLABORATING-CLINICSAMERICAN-COLLEGE-OF-RHEUMATOLOGY DAMAGE INDEX WITH MEASURES OF DISEASE-ACTIVITY AND HEALTH-STATUS IN PATIENTS WITH SYSTEMIC LUPUS-ERYTHEMATOSUS

Objective, To examine the internal consistency and validity of the Sys temic Lupus International Collaborating Clinics/American College of Rh eumatology Damage Index (SDI) with respect to disease activity, health status, and medication score. Methods, A prospective cross sectional study of patients with systemic lupus erythematosus (SLE) attending a specialist lupus outpatient clinic between July 1994 and February 1995 . The internal consistency of the SDI components was examined using Cr onbach's coefficient alpha. The associations of the SDI components wit h disease activity measured by the British Isles Lupus Assessment Grou p (BILAG) index, health status measured by the Medical Outcomes Study (MOS) Short Form 20, and with a medication score were analyzed using S pearman's rank correlation coefficient (rho). Results, 133 women and 8 men ranging in age from 20.1 to 88.7 years (mean 41.1, SD 12.5) were studied. With few exceptions, the components of the SDI that reflect d amage in different organ systems were not associated with each other. We found a significant although weak relationship between some related SDI and BILAG components (rho 0.25 to 0.28; p < 0.01), While damage t o the musculoskeletal system was associated with limitations in physic al functioning measured with the MOS Short Form 20 (rho -0.30; p < 0.0 1) and renal damage inversely with fatigue (rho -0.23; p < 0.01) there was no significant relationship of other SDI components with the MOS Short Form 20. Renal and neuropsychiatric damage were associated signi ficantly with the medication score (rho 0.27 and 0.23; p < 0.01), Conc lusion, The components of the SDI are valid in that they are associate d with disease activity in the respective organ systems and some of th em with a medication score. However, damage in different organ systems in SLE does not follow a common pattern. It is thus suggested that th e SDI profile be used in addition to the SDI total score as an endpoin t in clinical and epidemiological studies.