To develop and test the Brief Index of Lupus Damage (BILD), an interviewer-administered measure of damage in systemic lupus erythematosus (SLE), for use in epidemiologic studies in which administration of the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SDI) by trained physicians is not possible or feasible. In addition, we compared the BILD to another recently developed patient-reported measure, the Lupus Damage Index Questionnaire (LDIQ), which was designed as a written survey.
A sample of 81 patients from 2 university-affiliated SLE clinics was used to test the criterion validity of the BILD and the LDIQ. A second sample, the Lupus Outcomes Study (n = 728), was used to ascertain the construct validity of the BILD.
We found good agreement between most BILD items and corresponding SDI items, and moderately high overall Spearman's rank correlations for SDI with BILD (0.64) and with LDIQ (0.54). BILD scores were higher among older individuals, those with longer disease duration, and those with higher mean disease activity in the preceding 4 years. In addition, higher BILD scores were associated with poorer self-rated health and functional status, greater unemployment and work disability, and increased health care utilization.
We developed and performed a preliminary validation study demonstrating content, criterion, and construct validity of a new practical patient-reported instrument of SLE disease damage. Although further studies are needed to examine reliability and to document psychometric properties in other populations, the BILD appears to represent a promising tool for studies of SLE outside the clinical setting.