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Table 2 Risk factors associated with active systemic lupus erythematosus (n = 573)

From: Hydroxychloroquine levels in patients with systemic lupus erythematosus: whole blood is preferable but serum levels also detect non-adherence

  Univariate analysis Multivariate analysis
SLEDAI ≤ 4 (n = 492) SLEDAI > 4 (n = 81) P value Odds ratio CI95% P value
Male sex, n (%) 41 (8.3) 9 (11.1) 0.4    
Age (years) 29.1 ± 12 29.9 ± 10 0.58    
Active smoking, n (%) 108 (22) 22 (27.2) 0.3    
Corticosteroids, n (%)* 307 (62.4) 66 (81.5) 0.001 2.033 1.019–4.056 0.044
Immunosuppressants, n (%)* 79 (16.1) 24 (29.6) 0.003 1.999 1.081–3.697 0.027
HCQ whole-blood level (ng/mL) 940.8 ± 448 765.9 ± 426 0.001 0.999 0.997–1.000 0.023
HCQ serum level (ng/mL) 479.9 ± 218 404.9 ± 244 0.008    
DCQ whole-blood level (ng/mL) 116.7 ± 54 108.8 ± 59 0.2    
DCQ serum level (ng/mL) 63.6 ± 31 56.3 ± 33 0.051    
BMI (kg/m2) 23.9 ± 4.7 24.5 ± 5.3 0.64    
Haemoglobin (g/dL) 13.2 ± 1.3 12.45 ± 1.4 < 0.001 0.768 0.630–0.937 0.009
Platelets (cells/mm3) 252.5 ± 72.5 254.5 ± 91 0.61    
Leukocytes (cells/mm3) 6400 ± 2380 5798 ± 2588 0.036    
Lymphocytes (cells/mm3) 1466 ± 705 1348 ± 726 0.13    
Neutrophils (cells/mm3) 4412 ± 2195 3966 ± 2488 0.069    
  1. BMI body mass index, CI95% confidence interval 95%, DCQ desethylchloroquine, HCQ hydroxychloroquine
  2. *Multi-colinearity between corticosteroids and immunosuppressants was assessed. The VIF coefficient (= 1.071) excludes any colinearity between these two variables