Annual Protocol Biopsies for Five Years in a Pediatric Kidney Transplant Program: A Single-Center Retrospective Experience.

BACKGROUND: Annual protocol biopsies may detect subclinical injury after pediatric kidney transplantation, but real-world five-year surveillance coverage and clinical yield are uncertain. We assessed coverage, histological yield, management consequences, and histology-function associations. METHODS: We conducted a retrospective cohort study of all 42 consecutive pediatric kidney transplant recipients transplanted between 2007 and 2017 and followed in a single pediatric nephrology program with annual surveillance biopsies. Analyses were based on accrued recipient-year surveillance opportunities; biopsies performed at scheduled times for a clinical indication were excluded from protocol-biopsy analyses. A random-intercept mixed-effects model related estimated glomerular filtration rate (eGFR) to a study-specific chronicity composite score and post-transplant year. RESULTS: Of 158 accrued surveillance opportunities, a protocol biopsy was attempted at 123 (77.8%); 94/158 (59.5%) opportunities in 36 recipients yielded evaluable histology. Abnormal findings occurred in 15/94 (16.0%) evaluable results, involving 10 recipients, and 4/15 (26.7%) were followed by a documented biopsy-driven management change. Seven abnormalities in years 1-2 occurred in seven different recipients, whereas all eight abnormalities in years 3-5 were confined to three recipients with consecutive abnormal biopsies. Higher chronicity scores were associated with lower concurrent eGFR (β = -4.49 mL/min/1.73 m2 per score point; 95% CI, -7.16 to -1.82; p = 0.001). CONCLUSIONS: Real-world surveillance coverage and interpretable yield were incomplete, and documented management impact was limited. These data do not establish a benefit of uniform annual surveillance and provide a rationale for prospective evaluation of risk-adapted strategies.