Table 2.

Characteristics of the 283 clinically indicated biopsies

CharacteristicTotal Biopsies, n=283uANG First Quartile, n=71uANG Second Quartile, n=71uANG Third Quartile, n=71uANG Fourth Quartile, n=70P Valuea
Time to biopsy,b mo36.9±55.534.5±3542.5±69.539.8±54.431±58.30.62
Indication of biopsy, n (%)
 Acute dysfunction234 (82)63 (88)55 (78)55 (78)61 (87)0.15
 Proteinuria25 (9)4 (5.5)8 (11)10 (4)3 (4)0.15
 BK virus viremia10 (3.5)1 (1.5)5 (7)3 (4)3 (4)0.15
 Anti-HLA DSAs12 (4)3 (4.5)4 (4)3 (5)3 (4)0.15
Plasma creatinine at biopsy, μmol/L214±123178±54174±61215±117289±183<0.001
Urine protein-to-creatinine ratio at biopsy, g/mmol0.1±0.180.03±0.050.07±0.10.16±0.250.15±0.21<0.001
Anti-HLA DSA at biopsy, n (%)94 (41)24 (40)20 (37)23 (40)27 (43)0.51
Diagnosis, n (%)
 TCMR21 (7)5 (7)2 (3)5 (8)8 (11)0.22
 AMR68 (24)14 (20)13 (18)21 (30)20 (29)0.27
 BKVN7 (2.5)2 (3)1 (1.5)1 (1.5)3 (4)0.65
 Borderline lesionsc17 (6)3 (4)4 (5)10 (14)00.21
 Nonspecific lesions43 (15)11 (15)14 (20)7 (10)11 (15)0.41
 IFTA212 (75)54 (77)50 (72)56 (78)51 (72)0.78
  • Values are means±SD unless otherwise noted. BKVN, BK Virus associated nephropathy; DSA, donor-specific antibody; TCMR, T cell–mediated rejection; AMR, antibody-mediated rejection; BKVN, BK virus–associated nephropathy, IFTA, interstitial fibrosis-tubular atrophy.

  • a The P value is for the comparison of KTRs across the quartiles of uANG, which refers to Ln(uANG/creatinine), with a one-way ANOVA.

  • b In KTRs with repeat biopsies, the period of time from transplantation to the first biopsy has been calculated.

  • c The chi-squared test is suspect, because 20% of the cells have expected count of less than five; the contingency table has been drawn using the median rather that quartiles.