Patient characteristics at the time of biopsy overall and stratified by C9 staining groups
| Overall sample n=30 | Tubular C9 positive (stain intensity 1–3) n=7 | Tubular C9 negative (stain intensity 0) n=23 | P value | |
| Demographics/clinical parameters | ||||
| Age, years | 35 (23–41) | 36 (31–56) | 27 (21–39) | 0.20 |
| Female sex, n (%) | 24 (80%) | 5 (71%) | 19 (83%) | 0.60 |
| Black, n (%) | 9 (30%) | 9 (30%) | 21 (70%) | 0.30 |
| Hispanic, n (%) | 11 (37%) | 4 (57%) | 7 (30%) | 0.37 |
| Hydroxychloroquine, n (%) | 24 (80%) | 4 (57%) | 20 (87%) | 0.12 |
| Prednisone, n (%) | 19 (63%) | 2 (29%) | 17 (74%) | 0.07 |
| Immunotherapy*, n (%) | 16 (53%) | 4 (57%) | 12 (52%) | >0.99 |
| SLEDAI-2K† | 11 (8–12) | 12 (10–12) | 10 (6–12) | 0.83 |
| Systolic BP, mm Hg | 120 (112–133) | 133 (113–150) | 120 (110–130) | 0.18 |
| Diastolic BP, mm Hg | 75 (67–86) | 80 (70–100) | 70 (65–84) | 0.24 |
| Laboratory parameters | ||||
| eGFR, mL/min/1.73 m2 | 111.2 (74.7–132.0) | 57.9 (16.1–139.6) | 118.2 (95.2–132.0) | 0.17 |
| Creatinine, mg/dL | 0.7 (0.6–0.9) | 1.6 (0.5–3) | 0.7 (0.6–0.8) | 0.23 |
| Proteinuria‡, g/24 hours | 2.9 (1.7–5.6) | 6.2 (3.3–13.1) | 2.4 (1.3–4.6) | 0.001 |
| Nephrotic range proteinuria§, n (%) | 11 (37%) | 5 (71%) | 6 (26%) | 0.07 |
| Albumin, mean±SD, g/dL | 3.0±0.7 | 2.5±0.6 | 3.1±0.7 | 0.05 |
| Hematuria¶, n (%) | 12 (40%) | 4 (57%) | 8 (35%) | 0.39 |
| Pyuria¶**, n (%) | 13 (43%) | 2 (29%) | 11 (48%) | 0.43 |
| Serum C3 <70 mg/dL, n (%) | 20 (67%) | 4 (57%) | 16 (70%) | 0.66 |
| Serum C4 <14 mg/dL, n (%) | 20 (67%) | 3 (43%) | 17 (74%) | 0.18 |
| dsDNA ≤75 IU/mL, n (%) | 13 (43%) | 3 (43%) | 10 (44%) | >0.99 |
All continuous variables presented as median (IQR) except for albumin.
*Mycophenolate mofetil, cyclophosphamide, tacrolimus, azathioprine, rituximab or belimumab.
†SLEDAI-2K= Systemic Lupus Erythematosus. Disease Activity Index 2000.
‡24-hour urine protein collection and, if not available, spot urine protein to creatinine ratio.
§Proteinuria>3.5 g/24 hours.
¶Presence of 5 or more red blood cells per high-power field.
**Presence of 5 or more white blood cells per high-power field.
BP, blood pressure; eGFR, estimated glomerular filtration rate.