Progression of IgA Nephropathy under Current Therapy Regimen in a Chinese Population

Abstract

Current therapy for IgA nephropathy mainly includes renin-angiotensin system inhibitors and adding steroids for patients with persistent proteinuria. This study aimed to evaluate kidney disease progression and its risk factors in a Chinese cohort under current therapy. Patients with IgA nephropathy followed up for at least 12 months from a prospective database were involved. Renal survival and the relationship between clinical parameters and composite kidney failure events (defined as end stage kidney failure or eGFR halving) were assessed. Overall, 703 patients between 2003 and 2011 were enrolled in this study, with a mean follow-up time of 45 months. Mean eGFR was 84.0 ml/min per 1.73 m(2), systolic BP was 124 mmHg, and time-averaged mean arterial pressure was 90.0 mmHg. Median proteinuria at baseline was 1.60 g/d, and time-averaged proteinuria was 0.80 g/d. The mean rate of eGFR decline was -3.12 ml/min per 1.73 m(2) per year (95% confidence interval, -19.07 to 11.80), and annual end stage kidney failure rate was 2.3%. Multivariate Cox regression analyses revealed that baseline eGFR (hazard ratio, 0.76 per 10 ml/min per 1.73 m(2); 95% confidence interval, 0.66 to 0.91), proteinuria at 6 months (hazard ratio, 1.53 per g/d; 95% confidence interval, 1.27 to 1.84), and systolic BP control at 6 months (hazard ratio, 1.36 per 10 mmHg; 95% confidence interval, 1.05 to 1.77) were associated with composite kidney failure events. Baseline eGFR (regression coefficient, -0.06; 95% confidence interval, -0.07 to -0.04), time-averaged proteinuria (regression coefficient, -0.21; 95% confidence interval, -0.25 to -0.16), and time-averaged mean arterial pressure (regression coefficient, -0.15; 95% confidence interval, -0.21 to -0.09) were independent predictors of the slope of eGFR by linear regression. Lower proteinuria and lower BP were associated with slower eGFR decline and lower risk of end stage kidney failure in patients currently being treated for IgA nephropathy.