Table 1.

Demographic, clinical, and histologic characteristics of patients with IgAN

CharacteristicMean±SD or Median (IQR), n=749Deficiency Group, n=39Sufficiency Group, n=437High Group, n=273P ValueaP Valueb
Baseline
 Age, yr34.7±12.138.4±11.435.1±11.933.3±12.30.100.052
 Sex (% men)362 (48.3)13 (33.3)193 (44.2)156 (57.1)0.190.001
 Initial proteinuria, g/d1.29 (0.69, 2.51)1.73 (0.64, 2.43)1.15 (0.67, 2.28)1.50 (0.84, 3.25)0.31<0.001
 Prodromic infection (%)256 (34.2)26 (66.7)138 (31.6)92 (33.7)<0.0010.56
 Gross hematuria (%)213 (28.4)16 (41.0)115 (26.3)82 (30.0)0.0490.28
 eGFR, ml/min per 1.73 m283.89±30.6488.52±30.4682.95±30.2484.72±31.340.270.46
 CKD stages 1/2/3/4–5c (%)345 (47.4)/231 (30.8)/141 (18.8)/32 (4.3)20 (51.3)/12 (30.8)/5 (12.8)/2 (5.1)197 (45.1)/136 (31.1)/87 (19.9)/17 (3.9)128 (46.9)/83 (30.4)/49 (17.9)/13 (4.8)0.710.85
 HBP, mmHg (%)369 (49.3)19 (48.7)211 (48.3)139 (50.9)0.960.50
 Oxford classificationd (%)
  M1609 (82.4)31 (79.5)357 (82.8)221 (82.2)0.600.82
  E1368 (49.8)22 (56.4)211 (49.0)135 (50.2)0.370.75
  S1481 (65.1)28 (71.8)277 (64.3)176 (65.4)0.350.76
  T1/T2220 (29.8)/123 (16.6)6 (15.4)/7 (17.9)132 (30.6)/72 (16.7)82 (30.5)/44 (16.4)0.310.89
  C1/C2334 (45.2)/68 (9.2)19 (48.7)/1 (2.6)192 (44.5)/34 (7.9)123 (45.7)/33 (12.3)0.540.05
Follow-up
 Follow-up interval, mo47.0 (26.0, 81.0)38.0 (19.0, 69.0)44.0 (25.0, 84.0)52.0 (27.5, 80.0)0.310.31
 Treated with immunosuppressive agents or prednisone (%)353 (47.1)13 (33.3)192 (43.9)148 (54.2)0.200.01
 RAS blocker (%)713 (95.2)38 (97.4)414 (94.7)261 (95.6)0.460.60
 Slope, ml/min per 1.73 m2 per year−2.91 (−5.22, −1.25)−4.28 (−5.84, −2.24)−2.85 (−5.13, −1.19)−2.89 (−5.72, −1.25)0.030.42
OutcomeNo. (%)Per 100 Patient-yrNo. (%)Per 100 Patient-yrNo. (%)Per 100 Patient-yrNo. (%)Per 100 Patient-yr
 50% Decline in eGFR102 (13.6)3.478 (20.5)6.4747 (10.8)2.9547 (17.2)3.970.070.01
 ESRD67 (8.9)2.279 (23.1)7.2938 (8.7)2.3732 (11.7)2.700.040.19
 Compositee112 (15.0)3.8310 (25.6)8.0851 (11.7)3.1951 (18.7)4.320.010.01
MBL
 Plasma MBL, ng/ml2690.3 (961.9, 4227.2)0.00 (0.00, 36.2)1661.6 (744.5, 2630.1)4842.4 (4067.8, 5687.4)<0.001<0.001
 Haplotype (frequency)
  LYPB205 (0.137)52 (0.667)150 (0.171)3 (0.006)<0.001<0.001
  LXPA176 (0.117)17 (0.218)130 (0.148)29 (0.053)
  LYPA96 (0.064)0 (0)65 (0.074)31 (0.057)
  LYQA178 (0.119)3 (0.038)98 (0.112)77 (0.142)
  HYPA827 (0.552)6 (0.077)421 (0.481)400 (0.735)
 Rare16 (0.011)0 (0)12 (0.014)4 (0.007)
  HYPB5 (0.003)0 (0)5 (0.006)0 (0)
  HYPD2 (0.001)0 (0)2 (0.002)0 (0)
  HXPA5 (0.003)0 (0)3 (0.003)2 (0.004)
  HYQA3 (0.002)0 (0)1 (0.001)2 (0.004)
  LYQC1 (0.001)0 (0)1 (0.001)0 (0)
  • Oxford classification: mesangial hypercellularity score (M1>0.5), the presence of endocapillary proliferation (E1: present), segmental glomerulosclerosis/adhesion (S1: present), severity of tubular atrophy/interstitial fibrosis (T1=26%–50%; T2>50%), and presence of crescent (C1: 1%–25%; C2: 26%–100%). IQR, interquartile range; HBP, high BP; RAS, renin-angiotensin system.

  • a P value was used to indicate the difference between the MBL deficiency group and the sufficiency group. A two-tailed P<0.05 was considered statistically significant.

  • b P value was used to indicate the difference between the MBL high group and the sufficiency group. A two-tailed P<0.05 was considered statistically significant.

  • c CKD stages 1–4 denote eGFR≥90, 60–89, 30–59, and 15–29 ml/min per 1.73 m2, respectively, according to the Kidney Disease Outcomes Quality Initiative.

  • d The Oxford classification was developed by the Working Group of the International IgA Nephropathy Network and the Renal Pathology Society. Oxford scores of ten patients were unavailable, because each of them had fewer than eight glomeruli.

  • e Composite outcome included 50% eGFR decline or ESRD, whichever occurred first.