Relationship of systemic type I interferon activity with clinical phenotypes, disease activity, and damage accrual in systemic lupus erythematosus in treatment-naive patients: a retrospective longitudinal analysis

Table 2 Comparison of characteristics between SLE patients with and without organ damage accrual stratified by SLICC damage index score

	SDI = 0 (n = 24)	SDI ≥ 1 (n = 16)	p value*
Female, n (%)	23 (96)	14 (88)	0.553
Age of onset, median (IQR), years	29 (24–41)	36 (24–46)	0.456
Observation period, median (IQR), years	7.9 (4.3–9.6)	5.7 (1.2–9.6)	0.308
SLEDAI-2K at baseline, median (IQR), score	10 (8–14)	14 (8–19)	0.207
Lupus nephritis^a, n (%)	9 (38)	11 (69)	0.105
Lupus anticoagulant positive, n (%)	5 (21)	7 (44)	0.166
Anti-cardiolipin antibody positive, n (%)	11 (46)	8 (50)	0.999
Number of patients who had flare^b, n (%)	14 (58)	8 (50)	0.748
Number of flares/patient, median (IQR), n	1 (0–1.75)	0.5 (0–1.75)	0.647
Serum IFN activity at baseline, median (IQR), score	57.3 (17.9–137.2)	150 (51.1–275.4)	0.018
Serum IFN activity at 2nd point, median (IQR), score	0.2 (0.0–6.0)	0.9 (0.0–15.5)	0.639
Induction dose of prednisolone, median (IQR), mg/day	38 (30–50)	43 (33–50)	0.273
Methylprednisolone pulse, n (%)	0 (0)	4 (25)	0.020
IVCY, n (%)	2 (8)	7 (44)	0.018
MMF, n (%)	8 (33)	8 (50)	0.339
HCQ, n (%)	5 (21)	7 (44)	0.166
CNIs, n (%)	11 (46)	9 (56)	0.748

CNIs calcineurin inhibitors, HCQ hydroxychloroquine, IFN type I interferon, IVCY intravenous cyclophosphamide, MMF mycophenolate mofetil, SDI Systemic Lupus International Collaborating Clinics (SLICC) damage index, SLEDAI-2K SLE Disease Activity Index 2000
^aThe presence of lupus nephritis (LN) was defined as proteinuria ≥ 0.5 g/24 h or biopsy-proven nephritis compatible with SLE according to the EULAR/ACR2019 criteria renal domain [23]
^bDisease flares were assessed according to the modified Safety of Estrogen in Lupus Erythematosus National Assessment (SELENA)-SLEDAI Flare Index without the physician global assessment (PGA) score [29]
*p values were calculated with the chi-square test, Fisher’s exact test, or Mann-Whitney test. p values < 0.05 were considered significant

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