Association between various factors and subsequent flare or damage accrual in mSACQ patients with SLE treated with ≤7.5 mg/day of prednisolone-equivalent GC assessed using Cox frailty proportional hazard models
| Factors/covariates of Cox frailty proportional hazard model | Overall flare (742 events) HR (95% CI) | Severe flare (271 events) HR (95% CI) | Damage accrual (180 events) HR (95% CI) |
| Initial prednisolone-equivalent GC dosage (mg/day) (per 1 mg increase) | 1.06 (1.03 to 1.09) | 1.11 (1.05 to 1.18) | 1.05 (0.99 to 1.12) |
| P value<0.001 | P value<0.001 | P value=0.098 | |
| Decrease in the prednisolone-equivalent GC dosage (mg/day)(per 1 mg decrease) | 1.003 (0.98 to 1.03) | 0.98 (0.96 to 1.01) | 0.97 (0.95 to 0.99) |
| P value=0.81 | P value=0.19 | P value=0.004 | |
| Antimalarial use (yes vs no) | 0.88 (0.72 to 1.07) | 0.87 (0.62 to 1.21) | 1.13 (0.77 to 1.65) |
| P value=0.21 | P value=0.41 | P value=0.53 | |
| Immunosuppressive use (yes vs no) | 1.162 (0.98 to 1.36) | 0.82 (0.63 to 1.08) | 1.18 (0.86 to 1.62) |
| P value=0.081 | P value=0.16 | P value=0.30 | |
| Disease duration (year) (per 1-year increase) | 1.01 (0.9998 to 1.02) | 0.996 (0.98 to 1.01) | 1.02 (1.01 to 1.04) |
| P value=0.054 | P value=0.61 | P value=0.009 | |
| SLEDAI-2K (per 1-unit increase) | 1.10 (1.05 to 1.14) | 1.20 (1.15 to 1.25) | 0.96 (0.90 to 1.01) |
| P value<0.001 | P value<0.001 | P value=0.13 | |
| Age at visit (year) (per 1-year increase) | 0.99 (0.98 to 0.997) | 0.99 (0.98 to 1.002) | Not assessed* |
| P value=0.005 | P value=0.13 | ||
| Gender (male vs female) | 0.974 (0.72 to 1.31) | 1.35 (0.85 to 2.15) | Not assessed* |
| P value=0.86 | P value=0.20 | ||
| Ethnicity (non-Asian vs Asian) | 0.87 (0.62 to 1.24) | 1.21 (0.68 to 2.18) | Not assessed* |
| P value=0.45 | P value=0.51 |
Cox frailty proportional hazard models were used to assess the risk of subsequent flare or damage accrual per 1 mg decrease of prednisolone, adjusting for other covariates with centre of enrolment as random effect. Factors/covariates except ‘initial prednisolone-equivalent GC dosage’ were those at subsequent visits.
*Not assessed due to the low number of events.
GC, glucocorticoid; mSACQ, modified serologically active clinically quiescent; SLE, systemic lupus erythematosus; SLEDAI-2K, Systemic Lupus Erythematous Disease Activity Index 2000.