Outcomes

The primary outcome was change in calculated eGFR using the CKD-EPI equations for either serum creatinine or serum cystatin C measurements.¹⁶ Baseline values of these biomarkers during the first 3 months were averaged, to minimise biological and assay noise in the estimates of initial renal status. To avoid spurious correlation with the initial measures, subsequent values, between 6 months and 2 years, were used to estimate the primary outcome.

Secondary outcomes included proteinuria; rapid progression of CKD, defined as a yearly decline of >5 ml/min/1.73 m² (planned analysis); and final eGFR at 24 months (post-hoc analysis).