Table 2.
Odds ratios (95% confidence intervals) for the risk of an SLE flare in the year after the HCQ measurement at T0*
| Demographic data and comorbidities | Overall (n = 660) | SLE flare within one year a | ||
|---|---|---|---|---|
| Patients (n = 191) | Univariate OR (95% CI) | Multivariate OR (95% CI) b | ||
| Age at serum sample, mean ± SD, y | 36.2 ± 13.5 | 33.3 ± 12.2 | 0.98 (0.96–0.99) | 0.98 (0.97–0.99) |
| Male, n (%) | 580 (87.9) | 167 (87.4) | 1.06 (0.63–1.75) | – |
| Black race, n (%) | 107 (16.2) | 47 (24.6) | 2.22 (1.45–3.40) | 2.09 (1.33–3.26) |
| Education level, n (%) | ||||
| Postsecondary | 413 (62.6) | 116 (60.7) | Reference | Reference |
| High school or less | 247 (37.4) | 75 (39.3) | 1.12 (0.79–1.58) | 1.10 (0.76–1.58) |
| Cigarette smoking, n (%) | ||||
| Nonsmoker | 437 (66.2) | 127 (66.8) | Reference | |
| Current or past smoker | 222 (33.6) | 63 (33.2) | 0.97 (0.67–1.38) | |
| BMI, mean ± SD, kg/m2 | 25.8 ± 6.1 | 25.9 ± 6.0 | 1.00 (0.98–1.03) | |
| SLEDAI‐2K at T0, mean ± SD | 4.8 ± 4.9 | 5.9 ± 5.7 | 1.06 (1.02–1.10) | 1.05 (1.01–1.09) |
| Corticosteroids, n (%) | 438 (66.4) | 137 (71.7) | 1.42 (0.99–2.06) | 1.00 (0.67–1.51) |
| Azathioprine, n (%) | 91 (13.8) | 38 (19.9) | 1.95 (1.23–3.07) | 1.63 (0.99–1.51) |
| HCQ adherence, n (%) | ||||
| Severe HCQ nonadherence | 48 (7.3) | 28 (14.7) | 3.86 (2.12–7.12) | 3.32 (1.78–6.28) |
| Nonquantifiable | 28 (4.2) | 16 (8.4) | 3.48 (1.62–7.67) | |
BMI, body mass index; CI, confidence interval; HCQ, hydroxychloroquine; IV, intravenous; OR, odds ratio; SLEDAI‐2K, Systemic Lupus Erythematosus Disease Activity Index 2000; T0, time zero.
An SLE flare was defined by occurrence of one of the following events in the first year after the T0 visit: (a) ≥4 points in the SLEDAI‐2K; (b) new start in prednisone (oral or pulsed) or other immunosuppressive agent (azathioprine, methotrexate, mycophenolate mofetil, rituximab, oral or IV cyclophosphamide); and/or (c) new renal involvement including active nephritis, new nephrotic syndrome, new dialysis, or kidney transplantation.
The following variables were included in the multivariate model: age, Black race, education level (postsecondary; high school or less), SLEDAI‐2000, corticosteroids, azathioprine, and severe HCQ nonadherence. No interaction was found between nonadherence to HCQ and age (P = 0.51), education (P = 0.47), Black race (P = 0.26), SLEDAI‐2K (P = 0.59), azathioprine (P = 0.23), or with corticosteroids (P = 0.49).