Table 3.
Hazard ratios (95% confidence intervals) for the risk of damage (≥1‐point increase of the SLICC damage index) in the five years after measurement of serum hydroxychloroquine level at time zero (T0) (n = 660)*
| Demographic data and comorbidities | Overall, n = 660 | ≥1‐point increase in SLICC damage index within 5 years | ||
|---|---|---|---|---|
| n events (%) or mean ± SD, n = 167 | Univariate OR (95% CI) | Multivariate OR (95% CI) | ||
| Age at serum sample, mean ± SD, y | 36.2 ± 13.5 | 39.0 ± 15.3 | 1.02 (1.01–1.03) | 1.02 (1.01–1.03) |
| Male, n (%) | 80 (12.7) | 20 ± 12.0 | 1.04 (0.65–1.65) | |
| Black race, n (%) | 107 (16.2) | 36 ± 21.6 | 1.59 (1.10–2.30) | 1.64 (1.11–2.42) |
| Education level, n (%) | ||||
| Post‐secondary | 413 (62.6) | 80 ± 47.9 | Reference | Reference |
| High school or less | 247 (37.4) | 87 ± 52.1 | 2.02 (1.49–2.73) | 1.92 (1.40–2.63) |
| Cigarette smoking, n (%) | ||||
| Non‐smoker | 437 (66.2) | 97 ± 58.1 | Reference | |
| Current or past smoker | 222 (33.6) | 69 ± 41.3 | 1.52 (1.12–2.07) | |
| BMI, kg/m2, mean ± SD | 25.8 ± 6.1 | 26.8 ± 6.5 | 1.03 (1.01–1.06) | |
| SLEDAI‐2K at T0, mean ± SD | 4.8 ± 4.9 | 5.4 ± 5.5 | 1.03 (1.00–1.06) | 1.03 (1.00–1.06) |
| Treatment at T0, n (%) | ||||
| Corticosteroids | 438 (66.4) | 118 ± 70.7 | 1.28 (0.92–1.79) | |
| Azathioprine | 91 (13.8) | 36 ± 21.6 | 2.01 (1.39–2.90) | 1.85 (1.26–2.73) |
| Hydroxychloroquine | ||||
| Severe HCQ nonadherence | 48 (7.3) | 15 ± 9.0 | 1.47 (0.86–2.49) | 1.30 (0.74–2.29) |
| Nonquantifiable serum levels | 28 (4.2) | 11 ± 6.6 | 1.99 (1.08–3.66) | |
Results are expressed as n (%) for categorical variables and mean ± SD for continuous variables. The following variables were included in the multivariate model: age, Black race, education level (post‐secondary; ≤ high school), SLEDAI‐2000, azathioprine, and severe HCQ nonadherence.
BMI, body mass index; CI, 95% confidence interval; HCQ, hydroxychloroquine; kg/m2, kilograms per square meter; OR, odds ratio; SD, standard deviation; SLICC, Systemic Lupus International Collaborating Clinics; SLEDAI‐2K, Systemic Lupus Erythematosus Disease Activity Index 2000.