Longitudinal validation of the Brief Index of Lupus Damage

To provide further validation of the Brief Index of Lupus Damage (BILD), assessing its sensitivity to change in disease status and ability to predict mortality risk.

Data were from the University of California, San Francisco Lupus Outcomes Study (n = 958), in which the BILD was administered twice, approximately 5 years apart. We examined disease activity and health care utilization among participants who completed the BILD twice (n = 745). We identified increases in disease activity and utilization that would suggest a disease flare between the 2 BILD administrations and compared their occurrence by BILD score increases (0, 1, 2, 3, >3). Deaths were ascertained when annual interviews were attempted. Kaplan-Meier life-table analysis compared mortality rates for 4 groups of initial BILD scores (0, 1, 2, ≥3), and differences were tested using a log rank test. Using Cox proportional hazards models, we estimated the risk of death associated with higher BILD scores.

BILD score increases were associated with spikes in disease activity (P = 0.05) and physician visits (P = 0.004) over baseline, and with hospitalizations (P < 0.001) during the intervening years. Of those with BILD score increases >3, 84% were hospitalized prior to the second BILD. During followup, there were 60 deaths (6.3%). BILD scores of 2 (hazard ratio [HR] 6.1, 95% confidence interval [95% CI] 1.3-30.0) and ≥3 (HR 10.8, 95% CI 2.5-46.2) were associated with higher risk of death.

This analysis provides evidence of the predictive validity of the BILD and its ability to detect change. While not intended to replace clinical evaluation of disease damage, the BILD appears to be a useful tool for research.