Characteristics of patients with cSLE in comparison with healthy and patient control groups
| Patients with cSLE, n=16 | Patient controls (KTx) n=19 | Healthy controls n=19 | P value | |
| Clinical characteristics | ||||
| Age, years | 17.1 (13.9, 18.8) | 17.1 (15.5, 21) | 17.7 (13.8, 18.6) | 0.27 |
| Sex (female), n (%) | 12 (75) | 8 (42) | 10 (53) | 0.18 |
| Time after second dose of vaccination, weeks (sampling time) | 27.7 (9.4, 28.1)a | 6.5 (4.9, 12)b | 18.1 (5.2, 27.8)a,b | 0.001 |
| History of COVID-19 infection, n (%) | 9 (56)a,b* | 4 (21)b | 11 (61)b | 0.03 |
| Age at the start of IS treatment, years | 11.8 (0.8, 15.2) | 10.7 (9, 13) | 0.48 | |
| Time from the start of IS treatment to vaccination, years | 3.9 (2.5, 8.4) | 5.9 (2.9, 8.3) | 0.65 | |
| Follow-up duration, months | 63.8 (43.5, 164.3) | 87 (55, 121) | 0.83 | |
| Laboratory findings | ||||
| V-white cell count, ×109/L | 5.6 (5.5, 6.8) | 9 (7, 10.3) | NA | <0.001 |
| V-lymphocytes, ×109/L | 1.9 (1.4, 2.2) | 2.6 (2.1, 3.4) | NA | 0.003 |
| V-neutrophils, ×109/L | 4.3 (3.6, 4.8) | 5.2 (4.5, 6.8) | 0.011 | |
| eGFR, mL/min/1.73 m2 | 118 (108.5, 134.7) | 64 (54.8, 81) | <0.001 | |
| Immunosuppression treatment | ||||
| Multiple immunosuppressive agents, n (%)† | 5 (31) | 19 (100) | <0.001 | |
| Steroid use, n (%) | 10 (62) | 19 (100) | 0.004 | |
| Steroid dose >10 mg/day, n (%) | 5 (50) | 0 | 0.002 | |
| MMF, n (%) | 6 (37.5) | 19 (100) | <0.001 | |
| MMF dose, mg/m2 | 1166 (714, 1333) | 680 (651, 757) | 0.07 | |
| AZA, n (%) | 5 (31) | 0 | 0.013 | |
| CNI, n (%) | 0 | 19 (100) | <0.001 | |
| HCQ, n (%) | 15 (94) | 0 | <0.001 | |
| CYC, n (%)‡ | 1 (6) | 0 | 0.46 | |
| RTX, n (%)‡ | 0 | 0 | ||
Data are presented as median (25th, 75th percentile) or n/N (%). Continuous data were analysed by Mann-Whitney U test for two-group and the Kruskal-Wallis test for three-group comparisons. χ2 test or Fisher’s exact test was used for categorical variables, where appropriate.
Different superscript letters (a, b) within a row represent significant differences between medians at the 0.05 alpha level after corrections for multiple comparisons.
P values lower than 0.05 are given in bold.
*Nucleocapsid protein antibody test indicates prior COVID-19 infection was assessed only in patients with cSLE.
†Patients with cSLE were receiving steroid and MMF or AZA; KTx recipients were receiving steroid, MMF and CNI.
‡Receiving 6 months prior to the vaccination.
AZA, azathioprine; CNI, calcineurin inhibitors; cSLE, childhood-onset SLE; CYC, cyclophosphamide; eGFR, estimated glomerular filtration rate; HCQ, hydroxychloroquine; IS, immunosuppressive; KTx, kidney transplant recipients; MMF, mycophenolate mofetil; NA, not available; RTX, rituximab; V, white cell count, lymphocytes and neutrophil count at vaccination.