To examine the external validity of the Lupus Impact Tracker (LIT), a systemic lupus erythematosus (SLE)-specific, health-related quality of life (HRQoL) tool in a population-based cohort of patients with SLE in Atlanta, Georgia. We modeled the association of LIT scores with patient-reported measures of SLE activity (Systemic Lupus Activity Questionnaire [SLAQ]) and organ damage (self-administered Brief Index of Lupus Damage [SA-BILD]). We investigated the association of LIT scores with general HRQoL using the Short Form 12 (SF-12).
Correlation, multivariable regression, and longitudinal analyses using general linear modeling with fixed effects were performed to investigate the association between the LIT and patient-reported disease activity (SLAQ); patient-reported disease damage (SA-BILD); mental health (mental component summary [MCS] of the SF-12); and physical health (physical component summary [PCS] of the SF-12). Demographic trends related to the LIT were also assessed using cross-sectional analysis.
The LIT was significantly associated with disease activity (SLAQ), organ damage (SA-BILD), MCS scores, and PCS scores in both adjusted and unadjusted regression analysis (P < 0.0001). Longitudinal analysis demonstrated a significant association between the LIT and disease activity (SLAQ), MCS scores, and PCS scores (P < 0.0001), but not organ damage (SA-BILD).
The LIT is a simple, patient-centered tool that can be used to assess HRQoL in patients with SLE. This study provides external validity of the LIT in a population-based cohort with a large number of African American patients with a relatively high disease burden.