To evaluate the Renal Activity Index for Lupus (RAIL) as a predictor of kidney inflammation and treatment response in lupus nephritis patients.
Key Findings:
RAIL scores decreased over time and were lower in patients achieving complete renal response.
RAIL demonstrated accuracy in identifying complete renal response with AUC values of 0.83 to 0.85.
RAIL outperformed eGFR in distinguishing renal response, while UPCR showed moderate performance.
Higher RAIL scores indicated nonresponse at the next visit, while lower scores indicated subsequent complete renal response.
Interpretation:
The RAIL index is a promising noninvasive tool for assessing disease activity and predicting treatment response in lupus nephritis, complementing existing clinical measures.
Limitations:
Lack of repeat kidney biopsies limited direct comparison of biomarker changes with histologic disease activity.
Declining patient sample availability over time may have affected long-term estimates.
Findings may not be generalizable to routine clinical settings due to the study's clinical trial population.
Conclusion:
The RAIL index effectively identifies active lupus nephritis and predicts its course, supporting its use alongside clinical measures.
Ten-year observational data showed lower disease activity and functional disability coinciding with broader use of biologic and targeted synthetic therapies.
