REduced-dose Steroid PrOtocol for Childhood Nephrotic SyndromE (RESPONSE)

Study design: This is a pilot study for a planned multi-center, Bayesian adaptive, non-inferiority RCT (Figure 1). This planned multi-center RCT will require additional funding, which we will apply for if feasibility is shown by this pilot. This pilot is a single-center (SickKids) open-label RCT comparing reduced vs. standard-dose steroids to treat nephrotic syndrome relapses. Study population: We will include children (1-18 years) from Ontario, Canada that are diagnosed with idiopathic SSNS and present in relapse (≥3+ dipstick protein or protein:creatinine ratio ≥200mg /mmol for ≥3 consecutive days). We will exclude children that have received \>2 days of standard-dose prednisone; are on maintenance high-dose prednisone (\>0.3mg/kg per day or \>0.6mg/kg alternate days); have relapsed within the past 6 weeks; have grade 3+ peripheral edema (i.e., moderate-severe); are hospitalized; have stage 2+ acute kidney injury; or have thromboembolism. Children receiving other steroid-sparing immunosuppressives are eligible, but target drug levels will remain constant until the 2-week visit. No additional laboratory or imaging tests are needed, to maximize recruitment. Interventions: Reduced-dose steroids (intervention): oral prednisone 30mg/m2 (1mg/kg; max 40mg) daily until remission, then 20mg/m2 (0.66mg/kg; max 25mg) on alternate days for four weeks. Standard-dose steroids (control): oral prednisone 60mg/m2 (2mg/kg; max 60mg) daily until remission, then 40mg/m2 (1.5mg/kg; max 50mg) on alternate days for four weeks. Randomization 1:1 using permuted blocks. If a participant does not achieve remission by 2-weeks, develops symptomatic edema, stage 2+ acute kidney injury, or thromboembolism, they will be escalated to standard-dose steroids. Outcomes: The primary outcome is recruitment rate (number enrolled per month), since it is the greatest anticipated barrier to RCT feasibility. Other feasibility, tolerability, and safety outcomes are listed in Table 1. The pilot study will test case report forms, data management, quality control, and training systems. We will estimate treatment effect for the full-scale RCT's primary outcome (complete remission without steroid dose escalation by 2-weeks), to re-estimate sample size and evaluate full-scale RCT feasibility. Sample size: For this pilot study, we will recruit 50 children (25 per arm), which is 15% of the estimated sample size of the full-scale RCT. Sample size for this pilot must be adequate to assess RCT feasibility.