Overall | P1 | P2 | P3 | P values | |
(A) Source population | |||||
All patients with SLE, N | 793 | 162 | 249 | 382 | – |
Patients with LN, N (%) | 557 (70.2) | 124 (76.5) | 174 (69.8) | 259 (67.8) | ns |
Patients with renal biopsy, N (%)* | 499 (89.6) | 106 (85.5) | 158 (90.8) | 235 (90.7) | ns |
Patients without renal biopsy, N (%)* | 58 (6.1) | 18 (14.5) | 16 (9.2) | 24 (9.3) | ns |
Lost to follow-up, N (%) | 21 (3.7) | 2 (1.2) | 6 (2.4) | 13 (3.4) | ns |
(B) Clinical features of patients with renal biopsy | |||||
Overall 499 patients | P1 106 patients | P2 158 patients | P3 235 patients | ||
Gender, female, N (%) | 427 (85.6) | 99 (93.4) | 139 (88) | 189 (80.4) | 0.004 |
Age at SLE diagnosis, years | 28.11±12.0 | 27±10.3 | 26.3±11.2 | 29.8±13 | 0.01 |
Age at LN diagnosis, years | 31.4±12.5 | 28.4±10.4 | 29±11.5 | 34.4±13.3 | 0.001 |
Disease duration before LN diagnosis, years | 3.3±5.3 | 1.3±1.3 | 2.6±4.5 | 4.6±6.3 | <0.0001 |
Follow-up duration, years | 12.7±9.8 | 20.5±13 | 15.8±7.8 | 6.8±4.3 | |
Weight, kg | 61.7±12.2 | 57.4±10.4 | 62±11.2 | 63.3±13.1 | ns |
Hypertension, N (%) | 240 (48.2%) | 56 (52.8%) | 77 (48.7%) | 107 (45.9%) | ns |
Serum creatinine, mg/dL | 1.2±1.1 | 1.8±1.8 | 1.2±0.8 | 1.0±0.7 | <0.0001 |
Creatinine clearance, mL/min | 86.3±41 | 72.2±45.1 | 83.7±36.6 | 94.1±40.2 | 0.0001 |
Proteinuria, g/24 hours | 4.1±3.7 | 3.6±2.7 | 4.5±4.0 | 4.1±3.9 | ns |
Urinary erythrocytes/HPF | 27.7±45.7 | 18.6±18.6 | 24.2±24.3 | 34.1±61.9 | 0.01 |
Serum albumin, g/dL | 3.0±0.7 | 2.7±0.7 | 3.0±0.7 | 3±0.7 | 0.005 |
Haematocrit, % | 33.5±6.2 | 33.3±7.3 | 33.8±5.5 | 33.4±6 | ns |
White blood cells/103/mL | 6252±3223 | 6258±2842 | 6180±2888 | 6299±3603 | ns |
Platelets/109/L | 240 302±96 198 | 230 422±103 282 | 252 193±97 365 | 236 641±91 640 | ns |
C3, mg/dL | 62.1±25.4 | 65.1±22.6 | 58.7±25.4 | 63.1±26.3 | ns |
C4, mg/dL | 13.7±14.3 | 20.7±20.2 | 14.7±15.8 | 10.2±8 | 0.001 |
Anti-dsDNA, positive N (%) (NA 25) | 414 (87.3) | 82 (93.6) | 128 (85.3) | 204 (90.3) | ns |
Urinary abnormalities | 203 (40.7) | 28 (26.4) | 60 (38) | 115 (48.9) | <0.0001 |
Nephrotic syndrome | 174 (34.9) | 32 (30.2) | 59 (37.3) | 83 (35.4) | ns |
Nephritic syndrome | 92 (18.4) | 31 (29.2) | 32 (20.3) | 29 (12.4) | 0.0001 |
Rapidly progressive renal insufficiency | 30 (9.0) | 15 (14.2) | 7 (3.9) | 8 (3.4) | <0.0001 |
Histological classes, N (%) | |||||
II | 22 (4.4) | 5 (4.8) | 4 (2.5) | 13 (5.5) | ns |
III† | 115 (23.1) | 23 (21.9) | 28 (17.8) | 64 (27.2) | ns |
IV† | 267 (53.7) | 56 (53.3) | 91 (58) | 120 (51.1) | ns |
V | 93 (18.7) | 21 (20) | 34 (21.7) | 38 (16.2) | ns |
VI | 2 (0.4) | 1 (0.9) | 1 (0.6) | 0 (0) | ns |
Activity index | 6.4±4.9 | 6.2±4.9 | 6.6±4.9 | 5.9±4.5 | ns |
Chronicity index | 2.0±2.2 | 2.6±2.5 | 2.0±2.2 | 1.6±2 | 0.0023 |
(A) Number of patients with SLE followed in the four centres (three Nephrology Units and one Rheumatology Unit) and number of patients with clinical diagnosis of lupus nephritis who underwent or did not undergo renal biopsy, overall and subdivided according to the different periods. (B) Clinical features at the time of lupus nephritis diagnosis in patients who underwent renal biopsy, overall and according to the three different periods. P values refer to t-test, Kruskal-Wallis test or χ2 test (with 2 df), according to the type and distribution of variables.
*Percentages refer to the number of patients who received renal biopsy (n=557).
†Class III+V: overall, four patients; P1, three patients; P2, one patient, P3, no cases. Class IV+V: overall, 31 patients; P1, 2 patients, P2, 8 patients; P3, 21 patients.
P, period; P1: 1970–1985; P2: 1986–2001; P3: 2002–2016.
C3/C4, complement components; HPF, high-power field; LN, lupus nephritis; NA, not available; N, number; ns, not significant; SLE, systemic lupus erythematosus.