Number 5
IgA nephropathy is one of the commonest forms of glomerulonephritis worldwide. Approximately one-third of patients with IgAN progress to end-stage renal failure. Prognostic factors include clinical parameters such as renal dysfunction, hypertension, level of proteinuria and presence of microhematuria, and biopsy features such as the presence of crescents and/or fibrosis. However, as the authors of my number 5 best paper point out "information about these clinical and histologic prognostic factors is mostly based on patients in whom diagnostic renal biopsy was performed because of proteinuria higher than 1–2 g/d. Few nephrologists currently indicate a renal biopsy in patients with isolated microhematuria or proteinuria lower than 0.5 g/d accompanied by microhematuria."
IgA nephropathy is one of the commonest forms of glomerulonephritis worldwide. Approximately one-third of patients with IgAN progress to end-stage renal failure. Prognostic factors include clinical parameters such as renal dysfunction, hypertension, level of proteinuria and presence of microhematuria, and biopsy features such as the presence of crescents and/or fibrosis. However, as the authors of my number 5 best paper point out "information about these clinical and histologic prognostic factors is mostly based on patients in whom diagnostic renal biopsy was performed because of proteinuria higher than 1–2 g/d. Few nephrologists currently indicate a renal biopsy in patients with isolated microhematuria or proteinuria lower than 0.5 g/d accompanied by microhematuria."
The paper is by Gutiérrez, et al from Spain, published in September 2012 in JASN.
Gutiérrez et al also point out: "few studies have analyzed long-term outcome and prognostic factors in patients with biopsy-proven IgAN, isolated microhematuria, and minimal proteinuria at presentation. This information is important to establish whether IgAN is a progressive disease and seek clinical or histologic findings that could predict a worse long-term outcome. Studies performed in China and Japan have suggested that IgAN presenting with hematuria and minimal proteinuria is usually a progressive disease, and few patients had a complete resolution of hematuria."
The Gutiérrez study comprised of a sample of 141 Caucasian patients with biopsy-proven IgA nephropathy who had minor abnormalities at presentation and a median follow-up of 108 months. None of the patients received corticosteroids or immunosuppressants. They reviewed renal biopsies using the Oxford classification criteria.
The results were as follows:
- 46 (32%) patients had mesangial proliferation, whereas endocapillary proliferation, focal glomerulosclerosis, and tubulointerstitial abnormalities were uncommon.
- Serum creatinine increases greater than 50% and greater than 100% were observed in five (3.5%) patients and one (0.7%) patient, respectively; no patients developed ESRD.
- After 10, 15, and 20 years, 96.7%, 91.9%, and 91.9% of patients maintained serum creatinine values less than a 50% increase, respectively.
- Using Cox proportional hazards regression, the presence of segmental glomerulosclerosis was the only factor that significantly associated with a greater than 50% increase in serum creatinine.
- Clinical remission occurred in 53 (37.5%) patients after a median of 48 months.
- Proteinuria greater than 0.5 and greater than 1.0 g/24 h developed in 21 (14.9%) and 6 (4.2%) patients, respectively. Median proteinuria at the end of follow-up was 0.1 g/24 h, with 41 (29.1%) patients having no proteinuria.
While this study was limited by sample size and was only based on a Spanish experience (and therefore not necessarily generalizable to other parst of the world such as the Asia Pacific), it is an important study because of the careful and long follow-up and because of it's implications.
The bottom-line - the long-term prognosis for Caucasian patients with IgA nephropathy who present with minor urinary abnormalities and normal renal function is excellent. These patients don't need to be treated aggressively with steroids and/or cytotoxic agents (assuming of course one believes that there is evidence to support efficacy for cytotoxic agents in IgAN).
