Effect of dapagliflozin on proteinuria and the slope of the estimated glomerular filtration rate in patients with immunoglobulin A nephropathy: A multicenter prospective study

Objective The sodium–glucose cotransporter-2 inhibitor dapagliflozin reduces proteinuria and slows the decline in estimated glomerular filtration rate in patients with chronic kidney disease. Dapagliflozin is reported to be effective in patients with immunoglobulin A nephropathy; however, there have been only a few real-world clinical trials involving patients with immunoglobulin A nephropathy. Therefore, we aimed to evaluate the effect of dapagliflozin in Japanese patients with immunoglobulin A nephropathy. Method We performed a multicenter, nonblinded, single-arm, prospective observational study involving 44 patients with immunoglobulin A nephropathy. Patients who had completed corticosteroid treatment and were currently undergoing renin–angiotensin system inhibitor therapy were primarily enrolled. Results At baseline, the mean estimated glomerular filtration rate was 56.2 ± 29.4 mL/min/1.73 m 2 , and the median urinary protein-to-creatinine ratio was 0.63 g/g (interquartile range: 0.32–1.22 g/g). The estimated glomerular filtration rate decreased significantly after 1 month and plateaued thereafter. The urinary protein-to-creatinine ratio significantly decreased in patients with higher proteinuria (>0.5 g/g), but not in those with less proteinuria (<0.5 g/g). The post-treatment estimated glomerular filtration rate slope was significantly attenuated compared with the pretreatment slope, especially in patients with a relatively rapid decline in estimated glomerular filtration rate. Conclusion Dapagliflozin reduces residual proteinuria, even after treatment with corticosteroids and renin–angiotensin system inhibitors, in patients with biopsy-confirmed immunoglobulin A nephropathy. These findings may guide future treatment strategies for immunoglobulin A nephropathy.