Increased risk of renal biopsy complications in patients with IgA-nephritis

Histological classification of Japanese IgA nephropathy with a small number of glomeruli using Bayes' theorem

In Japan an original pathological classification of IgA nephropathy was used, while Oxford classification of IgA nephropathy was used globally. The Oxford classification requires ≥ 8 glomeruli while the Japanese classification requires ≥ 10. Ninety-nine patients diagnosed with IgA nephropathy were included. To determine the accuracy of histological staging, we calculated the posterior probability using Bayes' theorem and adopted three model of prior distribution. First, the actual staging distribution was reclassified using the beta distribution (reclassified distribution). Second a model with the same distribution (actual distribution) as the actual staging was used. Third, a model assuming that all cases are equally distributed (equal distribution) was used. The median number of collected glomeruli was 12 (8-19). There were 33 cases (33%) wherein the glomerular count was ≤ 9. When only cases with ≥ 10 glomeruli were included, the median posterior probability was 91% (74-99) (actual distribution, 90% [74-98]; equal distribution, 85% [73-96]). Even among the 33 cases with ≤ 9 glomeruli, there were approximately 7 cases in which the posterior probability was ≥ 90% for each model. Using Bayesian probabilistic analysis, it was possible to evaluate the histologic classification of IgA nephropathy, even when the number of obtained glomeruli was ≤ 9.

Urinary exosomal circular RNAs of sex chromosome origin are associated with gender-related risk differences of clinicopathological features in patients with IgA nephropathy

BACKGROUND

There are arguments for individualized treatments and the necessity of non-invasive biomarkers for patients with IgA nephropathy (IgAN) according to gender, but the rationale remains unclear. We aimed to investigate the relationship between urine exosomal circular RNA (circRNA) levels, related genes, clinical features, and renal pathological features in IgA nephropathy patients of different genders.

METHODS

Clinicopathological data from patients of different genders from a multicenter cohort were retrospectively analyzed. We used the Oxford classification to examine the severity of pathological damage in these patients. We compared clinical features and renal pathologies between IgAN patients of different genders. Using findings of urine exosomal circRNAs from male IgAN patients, we analyzed the relationship between this factor, the regulated genes located on the sex chromosomes, and renal pathologies.

RESULTS

A total of 502 IgAN patients were included. The proportion of male patients with crescent formation was higher than that of females (p = 0.019). Multivariate logistic regression analysis showed that proteinuria was an independent marker for crescent formation in male and female patients with IgAN, while smoking and higher low-density lipoprotein cholesterol (LDL-C) levels were independent risk factors for crescent formation in males alone. Urine exosomal circRNA chrY:15478147-15481229- located on the Y chromosome in male patients was negatively correlated with the expressions of UTY in specific regions of the Y chromosome.

CONCLUSION

Compared with female patients, males with IgAN had more severe renal dysfunction and a higher probability of glomerular crescent formation. Urine exosomal circRNA chrY:15478147-15481229- might participate in the pathogenesis of IgAN in male patients by altering UTY expressions.

Frequency, Timing, and Prediction of Major Bleeding Complications From Percutaneous Renal Biopsy

Background and Objectives:

The risk and timing of bleeding events following ultrasound-guided percutaneous renal biopsy are not clearly defined.

Design setting, participants, and measurements:

We performed a retrospective study of 617 consecutive adult patients who underwent kidney biopsy between 2012 and 2017 at a tertiary academic hospital in London, Canada. We assessed frequency and timing of minor (not requiring intervention) and major (requiring blood transfusion, surgery, or embolization) bleeds and developed a personalized risk calculator for these.

Results:

Bleeding occurred in 79 patients (12.8%; 95% confidence interval [CI]: 10.4%-15.7%). Minor bleeding occurred in 67 patients (10.9%; 95% CI: 8.6%-13.6%). Major bleeding occurred in 12 patients (1.9%; 95% CI: 1.1%-3.4%); 2 required embolization or surgery (0.3%; 95% CI: 0.09%-1.2%) and 10 required blood transfusion (1.6%; 95% CI: 0.9%-3.0%). Seventy-three of 79 events were identified immediately on post-procedure ultrasound (92.4% of cases; 95% CI: 84.4%-96.5%). Four of 617 patients experienced a minor event not detected immediately (0.6%; 95% CI: 0.3%-1.7%). Two patients (0.3%; 95% CI: 0.09%-1.2%) suffered a major complication that was not recognized immediately; both required blood transfusions only. There were no deaths or nephrectomies. A risk calculator using age, body mass index, platelet count, hemoglobin concentration, size of the target kidney, and whether the kidney is native, or an allograft predicted minor (C-statistic, 0.70) and major bleeding (C-statistic, 0.83).

Conclusions:

This retrospective study of 617 patients who had percutaneous ultrasound-guided renal biopsies supports the safety of short post-biopsy monitoring for most patients. A risk calculator can further personalize estimates of complication risk (http://perioperativerisk.com/kbrc).

Epidemiology of IgA Nephropathy: A Global Perspective

IgA nephropathy (IgAN), or Berger's disease, is the most common primary glomerular disease worldwide, but varies largely in its geographic distribution. A systematic review of 1,619 publications from the five continental regions of the world was performed to assess the prevalence of IgAN in different worldwide regions and analyze factors responsible for geographic differences. All observational studies that described the prevalence and incidence data on glomerulonephritis were considered. IgAN is more frequent in Asian populations (45 cases per million population/y in Japan) than in Caucasians (31 cases per million population/y in France). These differences are owing to some relevant aspects: (1) systematic mass screening of urine in populations, as occurring in some Asian countries (Hong Kong, Japan, Korea, and Singapore), is not common in Western countries; (2) general practitioners and health care professionals in Western countries underestimate persistent microscopic hematuria and/or mild proteinuria in apparently healthy individuals causing late referral to a nephrologist; and (3) nephrologists adopt different indications for kidney biopsy in individuals with persistent urinary abnormalities. In addition, differences also are owing to the source of data, because the frequency of IgAN observed in a nephrology center with a high incidence of kidney biopsies is higher than in a regional renal biopsy registry that receives data from many centers. In conclusion, greater efforts should be made to diagnose IgAN earlier in individuals who manifest persistent microhematuria and/or mild proteinuria and to introduce less stringent indications for kidney biopsies. This preventive approach, followed by early therapy, may reduce the global burden of end-stage kidney disease caused by IgAN.

Desmopressin (Octostim®) before a native kidney biopsy can reduce the risk for biopsy complications in patients with impaired renal function: A pilot study

AIM

To evaluate whether the administration of desmopressin alters the risk for renal biopsy complications.

METHODS

A multicenter registry containing 576 native kidney biopsies (NKb) with a serum creatinine above 150 μmol/L in 527 patients (372 men and 155 women, median age 61 years) was used. Most of the data were prospective. At one of the hospitals all biopsies with creatinine above 150 μmol/L received desmopressin before biopsies (NKb 204). These were compared to outcome of biopsy complications against other centres where desmopressin was not given (NKb 372). Fisher's exact test, χ² analyses, univariate and multiple binary logistic regression were used. Data were given as odds ratio (OR) and confidence interval (CI). A two sided P-value of <0.05 was considered significant.

RESULTS

In NKb with creatinine >150 μmol/L, those with desmopressin had less overall (3.4% vs 8.4%, OR 0.39, CI 0.17-0.90) whereas major or minor complications were not different. While desmopressin did not exhibit difference in complications in men, women received less major (0% vs 8.6%, P = 0.03) and overall complications (0% vs 12.1%, P = 0.006). A multiple logistic regression revealed that, after adjusting for BMI, age and sex, prophylaxis with desmopressin showed less major (OR 0.38, CI 0.15-0.96) and overall complications (OR 0.36, CI 0.15-0.85).

CONCLUSION

Desmopressin given before a native kidney biopsy in patients with impaired renal function can reduce the risk for complications.

High Resistive Index in Transplant Kidneys Is a Possible Predictor for Biopsy Complications

BACKGROUND

Transplant kidney biopsies are performed to determine a histological diagnosis for specific patient treatment. The aim of this study was to investigate if Resistive Index (RI) could be a predictor for biopsy complications.

METHODS

In this study, 220 consecutive transplant kidney biopsies (136 men and 84 women; median age, 55.5 years) were prospectively included. RI (median, 0.7) was measured by use of ultrasound. Histological diagnoses and biopsy complications were registered. Biopsy needles were either 16- or 18-gauge. Biopsies were performed by radiologists and were carried out as an outpatient procedure (70%) or an inpatient procedure (30%). Usually three passes per biopsy were performed.

RESULTS

The overall complication rate was 6.8%, divided into major (4.5%) and minor (2.3%) complications. An RI ≥0.8 predicts major (13.3% versus 3.2%; risk ratio [RR], 4.2; confidence interval [CI], 1.3-14.1; P = .03) and overall biopsy complications (16.7% versus 5.3%; RR, 3.2; CI, 1.2-8.6; P = .04) compared with RI <0.8. In the group <0.8, RI correlated with age (r_s = 0.28, P < .001) and systolic blood pressure (r_s = 0.18, P = .02). In the group ≥0.8, RI correlated with degree of interstitial fibrosis (r_s = 0.65, P = .006) and systolic blood pressure (r_s = 0.40, P = .03). The multiple regression analysis showed that in the group <0.8, the RI correlated only with age (P < .001), whereas in the group ≥0.8, RI correlated only with the degree of interstitial fibrosis (P = .003).

CONCLUSIONS

An RI ≥0.8 indicates greater risk for major and overall biopsy complications and should result in greater caution after biopsy.

Safety of Percutaneous Ultrasound-Guided Kidney Biopsy in Patients with AA Amyloidosis

BACKGROUND

Bleeding is the most frequent complication of kidney biopsy. Although bleeding risk in patients with AA amyloidosis after kidney biopsy has not been studied in a large population, AA amyloidosis has long been perceived as a risk factor for bleeding. The aim of the present study was to evaluate post-biopsy bleeding risk in patients with AA amyloidosis.

METHODS

We retrospectively analyzed bleeding complications in 88 patients with AA amyloidosis and 202 controls after percutaneous kidney biopsy. All the kidney biopsies were performed under the guidance of real-time ultrasound with the use of an automated core biopsy system after a standard pre-biopsy screening protocol. Bleeding events were classified as major when transfusion of blood products or surgical or radiological intervention was required, or if the bleeding caused hypovolemic shock or death. Bleeding events that did not meet these criteria were accepted as minor.

RESULTS

The incidence of post-biopsy bleeding was comparable between AA amyloidosis and control groups (5.7 vs. 5.0%, p = 0.796). Major bleeding events were observed in 3 patients from each group (p = 0.372). Selective renal angiography and embolization were applied to 2 patients from the AA amyloidosis group. One of these patients underwent colectomy and died because of infectious complications. Bleeding events were minor in 2.3% of the patients with AA amyloidosis and 3.5% of the controls (p = 0.728).

CONCLUSIONS

AA amyloidosis was not associated with increased post-biopsy bleeding risk. Kidney biopsy is safe in AA amyloidosis when standard pre-biopsy screening is applied. Further data are needed to confirm these findings.