SLEDAI-2K Responder Index 50 captures 50% improvement in disease activity over 10 years.

OBJECTIVES: To determine the frequency and the time to complete recovery identified by Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) and the time to partial recovery identified by the SLEDAI-2K Responder Index 50 (SRI-50) in three laboratory systems over 10 years.
METHODS: This is a retrospective analysis of the data available from the Toronto Lupus Clinic over the last 10 years. Patients with SLEDAI-2K renal, immunological and hematologic active descriptors were identified. The percentage of descriptors with partial and complete recovery was studied at one year and over the study period. Descriptive analysis and the Kaplan-Meier estimator were applied to study the time to partial and complete recovery.
RESULTS: Of the 795 patients, 94% had an active system at some point during the study period. Partial recovery was shown in 66% of patients by SRI-50 for at least one descriptor over the study period. None of these partial findings identified would have been captured using SLEDAI-2K alone. The time to partial recovery identified by SRI-50 was shorter than the time to complete recovery identified by SLEDAI-2K.
CONCLUSION: The SRI-50 is a valid responder index derived form SLEDAI-2K and is very helpful in identifying clinically important improvement in active laboratory descriptors in an efficient time.