Table 1

Characteristics of the cohort: SLE patients with active LN, ANR-SLE, INR-SLE and population controls

LNANR-SLEINR-SLEPopulation controlsP value
Patients, n84637348ns
Sex, female (%)89.390.581.389.0ns
Age, M (SD)36.2 (13)37.9 (12)47.7 (16)38.6 (15)0.008
Disease duration2 (0–8)6 (1–12)7 (4.5–15.5)NA<0.0001
Ethnicity (Caucasian/Asian/African/Hispanic), n75/3/2/451/6/6/062/6/2/344/2/0/2ns
p-creatinine (µmol/L)68 (57–83)66 (58–73)67 (58–76)63 (56–71)ns
eGFR, mL/min/1.732105 (77–123)103 (89–121)95 (79–109)NA0.09
u-ACR (mg/mmol)45.3 (19.0–76.1)2.8 (1.5–3.8)1.4 (0.9–2.4)0.4 (0.3–0.5)<0.0001
Positive a-dsDNA*, %644625NA<0.0001
Low C3†, %70250NA<0.0001
Low C4†, %754515NA<0.0001
SLEDAI-2K score12 (8–18)6 (4–8)1 (0–2)NA<0.0001
No treatment, n (%)14 (16.6)7 (11.1)23 (31.5)NAns
Prednisolone, n (%)63 (75.0)45 (71.4)29 (39.7)NA<0.0001
Prednisolone (mg‡), M (SD)15 (13)8.5 (9.4)3.3 (5.7)NA<0.0001
Prednisolone ≥10 mg, %55.536.515.0NALR25.7<0.0001
Hydroxychloroquine, n (%)39 (46)38 (60)35 (48)NAns
DMARD any, n (%)38 (45)29 (46)18 (25)NA<0.0001
dt-p-IL-16, n (%)79 (100)60 (100)47 (100)38 (100)ns
p-IL-16 (ng/mL)0.43 (0.3–0.8)0.36 (0.2–1.0)0.25 (0.2–0.5)0.2 (0.16–0.5)0.0028
p-IL-16 (ng/mL), M (SD)6.2 (0.8)6.09 (0.98)5.8 (0.75)5.7 (0.89)ns
dt-u-IL-16, n (%)40 (47.6)4 (6.3)13 (17.8)2 (4.3)<0.0001
u-IL-16 (pg/mL)3§ (3§−33.1)n-dt¶n-dt¶n-dt¶<0.0001
u-IL-16 (pg/mL), M (SD)27.0 (42.5)5.2 (10.4)9.8 (34.2)3.4 (2.4)<0.0001
  • All variables are presented as median and IQR, if not indicated otherwise.

  • *Data on a-dsDNA status were missing in 9 patients with LN, 17 with ANR-SLE and 18 with INR-SLE.

  • †Data on C3 and C4 status were missing in 27 patients with LN, 3 with ANR-SLE and 9 with INR-SLE.

  • ‡Prednisolone dose or equivalent steroid dose.

  • §3 is an arbitrary value for non-detectable levels for analysis by non-parametric tests.

  • ¶Only undetectable levels found in the IQR.

  • ACR, morning albumin to creatinine ratio; a-dsDNA, anti-double-stranded DNA; ANR-SLE, active non-renal SLE; DMARD, disease-modifying antirheumatic drugs (detailed information is provided in online supplemental material); dt, detectable (detection limit was defined by ELISA manufacturer’s recommendations as >9 pg/mL); eGFR, glomerular filtration rate; IL, interleukin; INR-SLE, inactive non-renal SLE; LN, lupus nephritis; LR, likelihood ratio; M, mean; NA, data not analysed; n-dt, non-detectable; p, plasma; SLE, systemic lupus erythematosus; SLEDAI-2K, Systemic Lupus Erythematosus Disease Activity Index 2000; u, urine.