Clinicopathological characteristics and disease chronicity in native kidney biopsies in Flanders

Background

The Flemish Collaborative Glomerulonephritis Group (FCGG) registry provides complete population data on kidney disease epidemiology in the region of Flanders (Belgium), as it captures all native kidney biopsies performed in its population of 6.5 million inhabitants.

Methods

From 2017 until 2019, 2054 adult kidney biopsies were included from 26 nephrology centers (one biopsy per patient). Data on nephrotic and nephritic syndrome were available in 1992 and 2026 biopsies, respectively. In a subgroup of 898 biopsies containing ≥10 glomeruli from 2018 to 2019, disease chronicity was graded using the Mayo Clinic Chronicity Score (MCCS). The association between clinical variables and MCCS was determined using simple and multiple linear regression models.

Results

Nephrotic syndrome (present in 378 patients, 19.0%) was most frequently caused by minimal change disease in younger patients (18-44 years), membranous nephropathy in older patients (45-74 years) and amyloidosis in the elderly (>75 years). Nephritic syndrome (present in 421 patients, 20.8%) was most frequently caused by immunoglobulin A nephropathy (IgAN) in younger patients (18-64 years) and ANCA-associated vasculitis (AAV) in older patients (>64 years). AAV and IgAN were the most frequent underlying diagnoses in biopsies in which crescents were identified. In multivariable analysis, acute and chronic kidney disease and diagnoses of diabetic kidney disease, nephrosclerosis and hyperoxaluria/hypercalcemic nephropathy were associated with the highest MCCS increases.

Conclusions

The FCGG registry validates data from previous Western European registries and provides a snapshot of disease chronicity in the whole biopsied Flemish population.

Epidemiology of native kidney disease in Flanders: results from the FCGG kidney biopsy registry

Background

The Flemish Collaborative Glomerulonephritis Group (FCGG) registry is the first population-based native kidney biopsy registry in Flanders, Belgium. In this first analysis, we report on patient demographics, frequency distribution and incidence rate of biopsied kidney disease in adults in Flanders.

Methods

From January 2017 to December 2019, a total of 2054 adult first native kidney biopsies were included. A ‘double diagnostic coding’ strategy was used, in which every biopsy sample received a histopathological and final clinical diagnosis. Frequency distribution and incidence rate of both diagnoses were reported and compared with other European registries.

Results

The median age at biopsy was 61.1 years (interquartile range, 46.1–71.7); male patients were more prevalent (62.1%) and biopsy incidence rate was 129.3 per million persons per year. Immunoglobulin A nephropathy was the most frequently diagnosed kidney disease (355 biopsies, 17.3% of total) with a similar frequency as in previously published European registries. The frequency of tubulointerstitial nephritis (220 biopsies, 10.7%) and diabetic kidney disease (154 biopsies, 7.5%) was remarkably higher, which may be attributed to changes in disease incidence as well as biopsy practices. Discordances between histopathological and final clinical diagnoses were noted and indicate areas for improvement in diagnostic coding systems.

Conclusions

The FCGG registry, with its ‘double diagnostic coding’ strategy, provides useful population-based epidemiological data on a large Western European population and allows subgroup selection for future research.

Plasma adiponectin level is inversely correlated with albuminuria in overweight and obese nondiabetic individuals

OBJECTIVE

To explore the relationship between adiponectin and albuminuria in a large group of overweight and obese nondiabetic individuals after controlling for potential confounders.

MATERIAL AND METHODS

Detailed anthropometry, computed tomography-measured visceral abdominal adipose tissue, 24-h albuminuria, adiponectin and a series of biochemical parameters were assessed. Four hundred forty patients, predominantly of Caucasian origin, were included (80.2% female). A multiple linear regression model was developed, with albuminuria as the dependent variable and potential predictors as independent variables.

RESULTS

The mean age was 40±13 years, the mean body mass index was 35.7±6.6 kg/m2, and the median visceral abdominal adipose tissue was 142.4 (92.3-194.0) cm2. 10.9% of subjects exhibited microalbuminuria. The median adiponectin level was 9.08 (6.23-12.94) μg/ml, and the median fasting serum glucose level was 83 (77-89) mg/dl. The strongest significant univariate correlations with albuminuria were visceral abdominal adipose tissue (r=0.258, p<0.001), adiponectin (r=-0.265, p<0.001), waist circumference (r=0.250, p<0.001), waist-to-hip ratio (r=0.236, p<0.001) and high-density lipoprotein cholesterol (r=-0.211, p<0.001). The multiple linear regression model revealed a significant positive independent correlation between visceral abdominal adipose tissue and albuminuria (r=0.134, p=0.033), between fasting glucose levels and albuminuria (r=0.390, p=0.029) and between gender and albuminuria (r=0.107, p=0.038). A significant independent negative correlation was identified between adiponectin and albuminuria (r=-0.255, p=0.022).

CONCLUSIONS

We observed an independent inverse relationship between adiponectin and albuminuria in overweight and obese nondiabetic individuals. Further investigations are needed to confirm this finding and to clarify whether adiponectin is a risk marker or plays a causative role in developing obesity-induced nephropathy.

Can Bariatric Surgery be Considered Standard Therapy to Treat Type 2 Diabetes?

With the rapid increase in obesity there has been a pronounced increase in obesity-related metabolic disorders including type 2 diabetes, cardiovascular disease, dyslipidaemia and hypertension. Bariatric surgery is a highly effective treatment for achieving long-term weight loss and is increasingly recognised to have benefits in diabetes treatment and cause improvement in other metabolic factors. Recent small randomised trials reported better glycaemic control after surgical intervention compared to pharmacological therapy. Physiological studies suggest a surgery-specific, weight-independent effect on glucose homeostasis. Long-term efficacy is to be proven. Consensus on definition of diabetes and diabetes remission must be achieved. Larger multicentre, randomised trials need to be done to clarify the place of metabolic surgery in diabetes treatment algorithms.