Presentation (CTI)

OBJECTIVES: Immunoglobulin A nephropathy (IgAN) is the most common primary glomerular disease worldwide and is associated with a substantial lifetime risk of kidney failure. This systematic review aimed to identify recent data on the cumulative incidence of kidney failure in people with IgAN, and to assess the association between proteinuria and risk of disease progression.
METHODS: Literature searches were performed in the PubMed, EMBASE and Cochrane Library databases to identify studies that reported the incidence of kidney failure in people with IgAN. To focus on high quality, recent data, only studies published between 2019 and the present day enrolling at least 500 participants were included. Data were extracted on the incidence of kidney failure at each reported timepoint, as well as patient baseline characteristics and treatments received. Combined estimates of the cumulative incidence of kidney failure and hazard ratios quantifying the association between proteinuria and kidney failure risk were calculated using random effects meta-analyses.
RESULTS: The incidence of kidney failure in people with IgAN was reported in 38 studies. Of these, 23 studies enrolling 32,216 patients reported outcomes between 4 and 6 years post-diagnosis in a format suitable for pooling. This resulted in an estimated cumulative incidence of kidney failure at 5 years from diagnosis of 11.2% (95% confidence interval 7.4-15.8%). In addition, 13 studies reported the association between proteinuria and progression to kidney failure. Of these, four studies reported hazard ratios for risk of kidney failure per 1 g/day increase in 24-hour proteinuria suitable for pooling. The meta-analysis produced an estimated hazard ratio for development of kidney failure of 1.21 (95% confidence interval 1.10-1.33) per 1 g/day increase in proteinuria.
CONCLUSIONS: Progression to renal failure remains common in patients with IgAN, with each 1 g/day increase in proteinuria associated with a 21% increase in risk.