Table 3.

Baseline characteristics for progressors and nonprogressors classified according to initial excretion of β2-microglobulin ≥1.0 μg/min

ProgressorsNonprogressorsaPb
β2m ≥ 1.0β2m < 1.0β2m < 1.0β2m ≥ 1.0
Number of subjects (% male subjects)44 (75)16 (62)52 (65)17 (65)0.69
Age at time of biopsy (years)c57 (47 to 64)49 (44 to 58)49 (38 to 60)56 (51 to 64)0.02
Time between biopsy and urine analysis (months)2 (1 to 4)2 (0 to 2)1 (1 to 4)2 (1 to 4)0.88
Survival time (months)11 (6 to 25)16 (7 to 25)53 (28 to 84)41 (24 to 54)
MAP (mmHg)100 (89 to 112)94 (81 to 105)93 (86 to 104)99 (92 to 104)0.16
Laboratory
    serum creatinine (μmol/L)110 (97 to 119)90 (68 to 95)80 (70 to 87)86 (82 to 91)<0.001
    serum albumin (g/L)20 (17 to 24)23 (18 to 26)27 (23 to 31)22 (17 to 25)<0.001
    serum cholesterol (mmol/L)8.4 (7.0 to 9.8)8.5 (5.7 to 9.3)6.5 (5.5 to 7.7)6.1 (5.3 to 7.3)0.004
    eGFRMDRD4 (ml/min per 1.73 m2)58 (53 to 67)75 (65 to 97)85 (78 to 93)75 (67 to 80)<0.001
Urine samples
    proteinuria (g/10 mmol creatinine)10.7 (9.3 to 12.7)5.5 (4.8 to 8.7)6.2 (4.7 to 8.5)9.1 (5.9 to 11.0)<0.001
    β2-microglobulin (μg/min)7.8 (2.3 to 13.8)0.3 (0.1 to 0.5)0.1 (0.2 to 0.4)2.6 (1.3 to 7.7)
    α1-microglobulin (μg/min)106 (61 to 131)31 (20 to 44)22 (12 to 37)50 (39 to 83)
    IgG (mg/24 h)511 (356 to 776)157 (74 to 217)119 (62 to 219)351 (158 to 607)
    Selectivity index>d0.27 ± 0.080.11 ± 0.050.15 ± 0.070.21 ± 0.08<0.001
Medication (%)
    ACEi/ARB use at time of biopsy36201660.03
    ACEi/ARB use during follow-up100100981000.68
    statin use at time of biopsy2071060.26
    statin use during follow-up939384940.43
Outcomes
    progression (%)10010000
    50% rise in serum creatinine (n)1812
    25% rise and serum creatinine >135 μmol/L (n)240
    clinical progression (n)24
Spontaneous remission (%)
    partial remission: < 2.0 g/10 mmol009082
    partial remission: <3.5 g/10 mmol and ≥50% reduction009482
    complete remission004029
  • β2-microglobulin, β2m; MAP, mean arterial pressure; eGFRMDRD4, estimated GFR calculated with the Modification of Diet in Renal Disease formula; ACEi, angiotensin-converting enzyme inhibitor; ARB, angiotensin II receptor blocker.

  • a Misclassified progressors are those patients who did show progression but had uβ2m < 1.0 μg/min.

  • b ANOVA was used to compare continuous data between the four groups and chi-squared tests to compare medication use and gender.

  • c Values are medians with interquartile range in parentheses.

  • d Values are mean ± SD.