Long-term evaluation of the timing of corticosteroid therapy in an IgA nephropathy cohort.

Background: Current proposed KDIGO guidelines suggest systemic corticosteroid therapy to reduce glomerular inflammation in immunoglobulin A nephropathy (IgAN), however the optimal timing for initiating steroid treatment remains a topic of debate. This study evaluates the impact of early versus delayed steroid initiation on long-term outcomes in IgAN patients.

Methods: We conducted a retrospective study of 268 IgAN patients treated with corticosteroids for >3 months within 3 years of kidney biopsy. Patients were categorized into early therapy (steroids within 30 days) and delayed therapy (after 30 days). Propensity score matching created matched cohorts. Kaplan-Meier curves and Cox regression assessed outcomes. The primary endpoint was a composite renal outcome [estimated glomerular filtration rate (eGFR) >50% reduction, end-stage kidney disease or renal death]. Secondary endpoints included eGFR decline >30% or >40% and an eGFR slope and time-average proteinuria.

Results: Propensity score matching identified 191 individuals for analysis. The primary outcome was significantly better in the early therapy group, with a hazard ratio (HR) of 0.41 [95% confidence interval (CI) 0.17-0.96, P = .041]. Significant benefits were also observed for secondary outcomes, including a lower frequency of >30% and >40% eGFR decline in the early therapy group, with HRs of 0.48 (95% CI 0.24-0.98, P = .04) and 0.34 (95% CI 0.14-0.81, P = .01), respectively. Cox regression confirmed that the timing of steroid initiation (early vs delayed) was a significant factor associated with kidney progression [HR = 0.33 (95% CI 0.14-0.77), P = .01]. The average eGFR slope over 10 years was more favorable in the early therapy group (-1.0 ± 6.0 vs -2.9 ± 6.8 mL/min/1.73 m² per year, P = .039). No significant differences in baseline characteristics were found to influence the timing of steroid use in progressive IgAN.

Conclusions: Early corticosteroid therapy may help reduce renal decline and preserve long-term kidney function in IgAN patients requiring steroid treatment.