Table 1.
Characteristics of the study population before and after matching.
| Variables | Unmatched cohort | P value | Matched cohort | P value | ||
|---|---|---|---|---|---|---|
| <19 months (n=1391) | ≥19 months (n=593) | <19 months (n=493) | ≥19 months (n=493) | |||
| Recipient | ||||||
| Duration of dialysis (mo) | ||||||
| Median [interquartile range] | 2.0 [3–48] | 48.0 [19–288] | 3.0 [0–18] | 48.0 [19–288] | ||
| Mean (SD) | 4.2 (4.9) | 61.3 (42.4) | <0.001 | 4.4 (4.90) | 59.6 (40.44) | |
| Mean age, y (SD) | 45.3 (12.2) | 44.9 (12.1) | 0.570 | 46.0 (12.2) | 45.2 (11.9) | 0.327 |
| Female sex, n (%) | 544 (39.1) | 210 (35.4) | 170 (34.5) | 179 (36.3) | ||
| Body mass index, kg/m2 (SD) | 24.7 (69.9) | 23.1 (8.2) | 0.408 | 22.8 (3.4) | 23.3 (8.8) | 0.246 |
| Primary cause of ESRD, n (%) | <0.001 | 0.969 | ||||
| Glomerulonephritis | 217 (15.6) | 86 (14.5) | 65 (13.2) | 73 (14.8) | ||
| IgA nephropathy | 169 (12.1) | 36 (6.1) | 30 (6.1) | 32 (6.5) | ||
| Diabetes | 283 (20.4) | 115 (19.4) | 109 (22.1) | 98 (19.9) | ||
| Hypertension | 163 (11.7) | 95 (16.0) | 78 (15.8) | 76 (15.4) | ||
| FSGS | 32 (2.3) | 11 (1.9) | 9 (1.8) | 8 (1.6) | ||
| Polycystic kidney disease | 45 (3.2) | 24 (4.0) | 17 (3.4) | 18 (3.7) | ||
| Other/unknown | 482 (34.6) | 226 (38.1) | 185 (37.5) | 188 (38.1) | ||
| Hypertension, n (%) | 1201 (86.3) | 502 (84.7) | 0.360 | 426 (86.4) | 416 (84.4) | 0.417 |
| Diabetes mellitus, n (%) | 309 (22.2) | 120 (20.2) | 0.357 | 109 (22.1) | 101 (20.5) | 0.586 |
| Chronic hepatitis, n (%) | 63 (4.5) | 52 (8.8) | 0.021 | 35 (7.1) | 34 (6.9) | 1.000 |
| History of tuberculosis, n (%) | 50 (3.6) | 41 (6.9) | 0.002 | 26 (5.3) | 30 (6.1) | 0.680 |
| History of malignancy, n (%) | 31 (2.2) | 24 (4.0) | 0.035 | 16 (3.2) | 16 (3.2) | 1.000 |
| Cerebrovascular accident, n (%) | 34 (2.4) | 12 (2.0) | 0.682 | 8 (1.6) | 9 (1.8) | 1.000 |
| Congestive heart failure, n (%) | 4 (0.4) | 15 (2.5) | <0.001 | 4 (0.8) | 3 (0.6) | 1.000 |
| Coronary artery disease, n (%) | 72 (5.2) | 34 (5.7) | 0.692 | 30 (6.1) | 32 (6.5) | 0.896 |
| Arrhythmias, n (%) | 15 (1.1) | 14 (2.4) | 0.048 | 8 (1.6) | 8 (1.6) | 1.000 |
| Anticoagulant use, n (%) | <0.001 | 0.999 | ||||
| Antiplatelet | 144 (10.3) | 108 (18.2) | 79 (16.0) | 81 (16.4) | ||
| Warfarin | 5 (0.4) | 9 (1.5) | 5 (1.0) | 5 (1.0) | ||
| None | 1242 (89.3) | 476 (80.3) | 409 (83.0) | 407 (82.6) | ||
| Number of HLA mismatch (ABDR), (SD) | 3.1 (1.6) | 3.1 (1.6) | 0.948 | 3.1 (1.6) | 3.1 (1.5) | 0.617 |
| Number of HLA mismatch (DR), (SD) | 1.1 (0.6) | 1.1 (0.7) | 0.912 | 1.1 (0.7) | 1.0 (0.7) | 0.769 |
| PRA >20%, n (%) | 246 (17.7) | 110 (18.5) | 0.646 | 79 (16.0) | 94 (19.1) | 0.209 |
| Pre-DSA, n (%) | 80 (8.5) | 32 (9.2) | 0.683 | 83 (16.8) | 78 (15.8) | 0.667 |
| ABO incompatible, n (%) | 218 (15.8) | 101 (17.1) | 0.482 | 83 (16.8) | 78 (15.8) | 0.730 |
| Induction, n (%) | 0.586 | 0.888 | ||||
| Basiliximab | 1137 (81.7) | 490 (82.6) | 404 (81.9) | 404 (81.9) | ||
| Thymoglobulin | 76 (5.5) | 36 (6.1) | 26 (5.3) | 29 (5.9) | ||
| None | 178 (12.8) | 67 (11.3) | 63 (12.8) | 60 (12.2) | ||
| Calcineurin inhibitor, n (%) | 0.499 | 0.821 | ||||
| Cyclosporine | 505 (37.8) | 205 (35.8) | 177 (35.9) | 184 (37.3) | ||
| Tacrolimus | 832 (62.3) | 365 (63.8) | 314 (64.4) | 309 (62.7) | ||
| Antimetabolite, n (%) | 0.118 | 0.897 | ||||
| Mycophenolate mofetil | 679 (50.8) | 284 (49.7) | 250 (50.7) | 243 (49.3) | ||
| Myfortic acid | 389 (29.1) | 157 (27.4) | 146 (29.6) | 144 (29.2) | ||
| Azathioprine | 125 (9.3) | 67 (11.7) | 48 (9.7) | 58 (11.8) | ||
| CYT | 67 (5.0) | 40 (7.0) | 28 (5.7) | 28 (5.7) | ||
| None | 77 (5.8) | 24 (4.2) | 21 (4.3) | 20 (4.1) | ||
| Steroid, n (%) | 0.876 | 1.000 | ||||
| Maintenance | 1279 (95.5) | 548 (95.8) | 472 (95.7) | 473 (95.9) | ||
| Steroid withdrawal | 60 (4.5) | 24 (4.2) | 21 (4.3) | 20 (4.1) | ||
| Delayed graft function, n (%) | 21 (1.5) | 17 (2.9) | 0.066 | 12 (2.4) | 12. (2.4) | 1.000 |
| Donor | ||||||
| Mean age, y (SD) | 42.5 (11.1) | 41.8 (11.4) | 0.217 | 41.6 (11.3) | 41.8 (11.3) | 0.817 |
| Female sex, n (%) | 721 (51.8) | 302 (50.9) | 249 (49.5) | 247 (50.1) | ||
| Body mass index, kg/m2 (SD) | 24.4 (3.3) | 24.2 (3.2) | 0.451 | 24.3 (3.2) | 24.2 (3.3) | 0.778 |
| Current smoker, n (%) | 472 (33.9) | 180 (30.4) | 0.133 | 148 (30.0) | 156 (31.6) | 0.629 |
| Hypertension, n (%) | 58 (4.2) | 23 (3.9) | 0.860 | 24 (4.9) | 18 (3.7) | 0.430 |
| Diabetes mellitus, n (%) | 9 (0.6) | 1 (0.2) | 0.302 | 1 (0.2) | 1 (0.2) | 1.000 |
| Chronic hepatitis, n (%) | 8 (0.6) | 6 (1.0) | 0.326 | 3 (0.6) | 5 (1.0) | 0.723 |
| History of tuberculosis, n (%) | 28 (2.8) | 13 (2.2) | 0.589 | 8 (1.6) | 10 (2.0) | 0.812 |
| History of malignancy, n (%) | 10 (0.7) | 4 (0.7) | 1.000 | 1 (0.2) | 4 (0.8) | 0.370 |
| Relationship with recipient | 0.011 | 1.000 | ||||
| Related, n (%) | 915 (65.8) | 354 (59.7) | 299 (60.6) | 300 (60.9) | ||
| Unrelated, n (%) | 476 (34.2) | 239 (40.3) | 323 (65.5) | 314 (63.7) | ||
| 24-h creatinine clearance, mL/min (SD) | 117.4 (38.5) | 116.8 (26.9) | 0.704 | 117.5 (31.7) | 117.1 (27.4) | 0.814 |
| 24-h urine protein, mg/day (SD) | 90.4 (51.4) | 96.2 (90.8) | 0.143 | 93.8 (74.1) | 94.0 (32.8) | 0.960 |
| Kidney graft weight, g (SD) | 189.7 (51.8) | 192.3 (100.3) | 0.446 | 192.7 (68.9) | 88.2 (36.2) | 0.199 |
| eGFR (CKD-EPI),% (SD) | 103.9 (14.5) | 104.6 (14.5) | 0.290 | 105.3 (14.4) | 104.4 (14.7) | 0.321 |
SD – standard deviation; ESRD – end-stage renal disease; FSGS – focal segmental glomerulosclerosis; HLA – human leukocyte antigen; PRA – panel reactive antibody; DSA – donor-specific antibody; CYT – cyclophosphamide; eGFR – estimated glomerular filtration rate; CKD-EPI – Chronic Kidney Disease Epidemiology Collaboration.