Acute Treatment Effects on GFR in Randomized Clinical Trials of Kidney Disease Progression

Background: Acute changes in glomerular filtration rate (GFR) can occur following initiation of interventions for chronic kidney disease (CKD) progression. These complicate the interpretation of treatment effects on long term progression of (CKD). We sought to assess the magnitude and consistency of acute effects in randomized clinical trials (RCT) and explore factors that might impact them. Methods: We performed a meta-analysis of 53 RCTs for CKD progression enrolling 56,413 participants that had at least one estimated GFR measurement by six months following randomization. We defined acute treatment effects as the mean difference in GFR slope from baseline to 3 months between randomized groups. We performed univariable and multivariable meta-regression to assess the impact of intervention type, disease state, baseline GFR and albuminuria on the magnitude of acute effects. Results: The mean acute effect across all studies was -0.21 mL/min/1.73m2 (95% CI -0.63 to 0.22) over three months, with substantial heterogeneity across interventions (95% coverage interval across studies, -2.50 to +2.08 mL/min/1.73m2). Negative average acute effects were observed in renin angiotensin system blockade, blood pressure lowering and sodium-glucose cotransporter 2 inhibitor trials while positive acute effects were observed in trials of immunosuppressive agents. Larger negative acute effects were observed in trials with higher mean baseline GFR. Conclusion: The magnitude and consistency of acute GFR effects varies across different interventions, and is larger at higher baseline GFR. Understanding the nature and magnitude of the acute effects can help inform the optimal design of RCTs in CKD evaluating kidney disease progression.