The Implication of the KDIGO Clinical Practice Guidelines on Management of IgA Nephropathy

Since the publication of KDIGO guidelines, a few reviews had been published on the topic of IgA nephropathy [6, 7] and evaluation of the guidelines [8]. In particular, the National Kidney Foundation Kidney Disease Outcomes Quality Initiative (NKF-KDOQI) [9] and the Canadian Society of Nephrology [10] made specific comments on the chapter of IgA nephropathy.

Much insight can be gleaned from the discussion from these two documents [9, 10]. Their focuses were summarized in Table 14.2. A few points deserve mentioning. First, both commentaries highlighted the corticosteroid treatment threshold for IgA nephropathy: trial of corticosteroids should only be considered in patients with preserved renal function or glomerular filtration rate above 50 ml/min per 1.73 m². Admittedly, this is reasonable to draw such conclusion based on the inclusion criteria and subject profiles of the three major trials of corticosteroids [11–13]. Nonetheless, concern about corticosteroid side effects explains the need to emphasize the treatment criteria. The Canadian commentary advises the consideration of corticosteroids at the level of the individual patients, taking into account of their relative contraindications to steroid therapy [10]. And, as highlighted by the US commentary [9], a meta-analysis of corticosteroid treatment in IgA nephropathy suggested an increased efficacy with shorter-term high-dose therapy compared to longer-term low-dose therapy [14]. Second, the controversy of using mycophenolate mofetil can be demonstrated by the different views from the two commentaries. The US commentary generally agreed with the recommendation not to use mycophenolate mofetil in patients with IgA nephropathy, but hinted on the racial differences in the response to mycophenolate mofetil [9]. The benefit of mycophenolate mofetil in Asian patients, as shown in the reduction of proteinuria, a decrease in rate of decline in glomerular filtration rate and end-stage renal disease risk after 6 years of follow-up [15, 16], was acknowledged in the commentary. On the other hand, the Canadian commentary argued against the use of mycophenolate mofetil and reminded us the potential toxicity (including severe pneumonia such as Pneumocystis pneumonia) as observed in observational studies, in line with what were recommended by the KDIGO guidelines.