Table 4.
Time-dependent survival analyses using three regression models with SLEDAI-2K, SLEDAI-2KG and SLEDAI organ systems
| Univariable cox regression | Multivariable analysis with SLEDAI-2K | Multivariable analysis with SLEDAI-2KG | |||||
| HR (95% CI) |
P value | HR (95% CI) |
P value | HR (95% CI) | P value | ||
| Demographics | Female sex | 1.89 (0.69 to 5.17) | 0.22 | 2.41 (0.76 to 7.67) | 0.13 | 2.51 (0.79 to 7.98) | 0.12 |
| Age at SLE diagnosis | 1.00 (0.98 to 1.02) | 0.77 | |||||
| Age at first visit | 1.00 (0.98 to 1.02) | 0.73 | |||||
| Caucasian | 1.46 (0.89 to 2.38) | 0.13 | 1.41 (0.85 to 2.32) | 0.18 | |||
| Study protocol | SLEDAI-2KG at each visit | 1.21 (1.10 to 1.33) | <0.0001 | 1.178 (1.06 to 1.31) | 0.002 | ||
| SLEDAI-2K at each visit | 1.06 (1.02 to 1.11) | 0.004 | 1.04 (0.99 to 1.09) | 0.11 | |||
| SDI score | 0.87 (0.72 to 1.10) | 0.14 | 0.84 (0.69 to 1.02) | 0.10 | 0.84 (0.69 to 1.02) | 0.09 | |
| Fibromyalgia | 0.94 (0.48 to 1.85) | 0.86 | |||||
| Treatment | Glucocorticoid Use | 1.66 (1.04 to 2.66) | 0.03 | Not entered into multivariable analysis, part of SLEDAI-2KG | |||
| Glucocorticoid dose (mg/day) | 1.02 (1.01 to 1.02) | 0.0001 | 1.01 (1.001 to 1.02) | 0.03 | |||
| Antimalarial | 1.19 (0.75 to 1.90) | 0.46 | |||||
| Treated with Immunosuppressives | 1.52 (0.98 to 2.36) | 0.06 | |||||
| Laboratory markers | Antiphospholipid antibody at any time | 0.94 (0.48 to 1.85) | 0.86 | ||||
| Leucopenia (WBC<4.0*10∧9 /L) | 1.27 (0.51 to 3.2) | 0.60 | |||||
| Neutropenia (<1.5* 10∧9) | 0.83 (0.40 to 1.73) | 0.62 | |||||
| Lymphopenia (<1.0* 10∧9) | 1.78 (1.12 to 2.80) | 0.01 | 1.63 (1.02 to 2.59) | 0.041 | 1.56 (0.98 to 2.49) | 0.06 | |
| Anaemia | 1.25 (0.78 to 2.02) | 0.36 | |||||
| Low IgA | 1.52 (0.21 to 10.10) | 0.68 | |||||
| Low IgG | 1.61 (0.39 to 6.58) | 0.51 | |||||
| Low IgM | 1.12 (0.35 to 3.55) | 0.85 | |||||
*All of the above variables were time-dependent with the exception of: female sex, age at SLE diagnosis, age at first visit and Caucasian ethnicity.
*In the third multivariable regression model with SLEDAI organ systems, lymphopenia was the only statistically significant predictor of HZ events (HR=1.64, 95% CI 1.03 to 2.95, p=0.037), the other adjusted variables in the model included SLEDDAI-2K organ systems, SDI and glucocorticoid dose which did not sustain significance. As a result this was not included in the above table.
HZ, herpes zoster; SLEDAI-2K, SLEDAI-2K, SLE Disease Activity Index 2000; SLEDAI-2KG, SLEDAI-2K Glucocorticoid Index; WBC, white blood cells.