The lupus impact tracker is responsive to changes in clinical activity measured by the systemic lupus erythematosus responder index

Objective The lupus impact tracker (LIT) is a 10-item patient reported outcome tool to measure the impact of systemic lupus erythematosus or its treatment on patients' daily lives. Herein, we describe the responsiveness of the LIT and LupusQoL to changes in disease activity, using the systemic lupus erythematosus responder index (SRI). Methods A total of 325 adult systemic lupus erythematosus patients were enrolled in an observational, longitudinal, multicentre study, conducted across the USA and Canada. Data (demographics, LIT, LupusQoL, BILAG, SELENA-SLEDAI) were obtained three months apart. Modified SRI was defined as: a decrease in SELENA-SLEDAI (4 points); no new BILAG A, and no greater than one new BILAG B; and no increase in the physician global assessment. Standardised response mean and effect size for LIT and LupusQoL domains were calculated among SRI responders and non-responders. Wilcoxon's test was used to compare the LIT and LupusQoL variation by SRI responder status. Results Of the participants 90% were women, 53% were white, 33% were of African descendant and 17% were Hispanic. Mean (SD) age and SELENA-SLEDAI at baseline were 42.3 (16.2) years and 4.3 (3.8), respectively. Mean (SD) LIT score at baseline was 39.4 (22.9). LIT standardised response mean (effect size) among SRI responders and non-responders were -0.69 (-0.36) and -0.20 (-0.12), respectively (P=0.02). For LupusQoL, two domains were responsive to SRI: standardised response mean (effect size) for physical health and pain domains were 0.42 (0.23) and 0.65 (0.44), respectively. Conclusions LIT is moderately responsive to SRI in patients with systemic lupus erythematosus. Inclusion of this tool in clinical care and clinical trials may provide further insights into its responsiveness. This is the first systemic lupus erythematosus patient reported outcome tool to be evaluated against composite responder index (SRI) used in clinical trials.