Renal biopsy reports in nephritic syndrome: Update

BACKGROUND: Nephritic syndrome (NiS) is a major indicator of serious renal diseases necessitating kidney biopsies for histopathological evaluations, but due to the lack of comprehensive reviews in the literature, the current understanding of the syndrome and its significance is limited. AIM: To collect all the evidence retrievable from the literature on the diagnoses made on the renal biopsies performed for NiS as the indication to the procedure. METHODS: A literature search was conducted to find studies reporting final diagnoses on renal biopsies in NiS patients. Data were pooled and analyzed with stratifications on age and regions. Meta-analyzes were performed using Stata v.9. RESULTS: Overall, 26414 NiS patients from the total number of 96738 kidney biopsy diagnoses reported by 47 studies from 23 countries from all continents (except sub-Saharan Africa) were found and analyzed. NiS was the indication for renal biopsy in 21% of the patient populations across the reviewed studies. Immunoglobulin A (IgA) nephropathy was the single most frequent diagnosis in these patients (approximately 38%) followed by lupus nephritis (approximately 8%) and Henoch Schönlein purpura (approximately 7%). IgA nephropathy was the most frequent diagnosis reported for the NiS patients from the East Asia, comprising half of all the cases, and least prevalent in South Asia. Considering the age subgroups, adult (vs pediatric or elderly) patients were by far the most likely age group to be diagnosed with the IgA nephropathy. A myriad of such regional and age disparities have been found and reported. CONCLUSION: As the indication for renal biopsy, NiS represents a very distinctive epidemiology of final renal disease diagnoses compared to the other major syndromes.