Abnormalities in Protocol Graft Kidney Biopsy 6 Months Posttransplantation in a Tertiary Care Center Hospital of Nepal

The Value of Protocol Biopsy in Kidney Transplantation on Monitoring Transplant Outcomes: A Systematic Review and Meta-Analysis

BACKGROUND

There is a great debate about the role of biopsies per protocol in kidney transplant recipients, and the published studies show contradictory results. We aimed to assess the safety and effectiveness of protocol biopsies in kidney transplant recipients in improving short- and long-term outcomes.

METHODS

We conducted searches until July of 2023 to identify all randomized clinical trials (RCT). Studies were identified through search strategies for CENTRAL, MEDLINE, EMBASE, and LILACS. Titles and abstracts were screened independently by 2 authors; 2 authors independently assessed retrieved abstracts and the full text. Assessment of risk of bias was carried out using the Cochrane risk of bias tool. The outcomes of interest were: Acute rejection, graft loss, mortality, glomerular filtration rate, and safety outcomes. Meta-analysis was performed for variables of interest when appropriate. Quality of evidence was assessed using GRADE methodology.

RESULTS

We screened 5,695 records. Four trials met all eligibility criteria. No benefit of protocol biopsy was found in detecting acute rejection (3 studies RR: 2.0, 95% CI: 0.68-5.85, p = .2) or preventing graft loss at 12 months (2 studies, RR 0.33, 95% CI 0.06-1.72, p = .19). No differences were found between the groups in the glomerular filtration rate at 6 months post-transplantation (2 studies, MD 2.97, 95% CI 1.4-7.3, p = .18). A total of 23 safety events were present in the biopsy group compared to six in the control group.

CONCLUSION

No benefit was found in performing protocol biopsy following kidney transplantation.

Prediction of very early subclinical rejection with machine learning in kidney transplantation

Protocol biopsy is a reliable method for assessing allografts status after kidney transplantation (KT). However, due to the risk of complications, it is necessary to establish indications and selectively perform protocol biopsies by classifying the high-risk group for early subclinical rejection (SCR). Therefore, the purpose of this study is to analyze the incidence and risk factors of early SCR (within 2 weeks) and develop a prediction model using machine learning. Patients who underwent KT at Samsung Medical Center from January 2005 to December 2020 were investigated. The incidence of SCR was investigated and risk factors were analyzed. For the development of prediction model, machine learning methods (random forest, elastic net, extreme gradient boosting [XGB]) and logistic regression were used and the performance between the models was evaluated. The cohorts of 987 patients were reviewed and analyzed. The incidence of SCR was 14.6%. Borderline cellular rejection (BCR) was the most common type of rejection, accounting for 61.8% of cases. In the analysis of risk factors, recipient age (OR 0.98, p = 0.03), donor BMI (OR 1.07, p = 0.02), ABO incompatibility (OR 0.15, p < 0.001), HLA II mismatch (two [OR 6.44, p < 0.001]), and ATG induction (OR 0.41, p < 0.001) were associated with SCR in the multivariate analysis. The logistic regression prediction model (average AUC = 0.717) and the elastic net model (average AUC = 0.712) demonstrated good performance. HLA II mismatch and induction type were consistently identified as important variables in all models. The odds ratio analysis of the logistic prediction model revealed that HLA II mismatch (OR 6.77) was a risk factor for SCR, while ATG induction (OR 0.37) was a favorable factor. Early SCR was associated with HLA II mismatches and induction agent and prediction model using machine learning demonstrates the potential to predict SCR.

Complications of Percutaneous Kidney Allograft Biopsy: Systematic Review and Meta-analysis

BACKGROUND

Kidney biopsy is important to guide the management of allograft dysfunction but has a risk of complications. This review aimed to determine the incidence and risk factors of complications after kidney allograft biopsy.

METHODS

This is a systematic review and meta-analysis of randomized controlled trials, cohort studies, or case-control studies indexed on PubMed, Embase, Cochrane Central Register of Controlled Trials, World Health Organization International Clinical Trials Registry, and ClinicalTrials.gov, limited to the English language, from January 2000 to December 2020, including adult and pediatric kidney allograft biopsies. Primary outcomes were gross hematuria, bleeding requiring transfusion, and major complications (requiring interventions such as blood transfusion or surgical or radiological interventions).

RESULTS

The review included 72 studies (40 082 biopsies). The quality of included studies was suboptimal. Pooled rates of gross hematuria, bleeding requiring transfusion, and major complications were 3.18% [95% confidence interval (95% CI), 2.31-4.19], 0.31% (95% CI, 0.15-0.52) and 0.89% (95% CI, 0.61-1.22), respectively. Gross hematuria rates were lower in high-income compared with middle-income countries (2.59% versus 6.44%, P < 0.01) and biopsies performed by radiology as compared with nephrology departments (1.25% versus 3.71%, P < 0.01). Blood transfusion rates were lower in pediatrics than adults (0.0% versus 0.65%, P < 0.01). Major complications were lower in biopsies performed by specialists as compared with trainees (0.02% versus 3.64%, P < 0.01). Graft loss and mortality were extremely rare. Limitations included missing data, few randomized controlled trials, and possible publication bias.

CONCLUSIONS

The risk of complications after kidney allograft biopsy was low. Given the low quality of included studies, risk factors for complications should be further examined in future studies.