The additive effects of hydroxychloroquine to maintenance therapy with standard of care in patients with systemic lupus erythematosus

AIM: In this retrospective study, the effect of hydroxychloroquine (HCQ) added to maintenance therapy according to the standard of care (SoC) was evaluated for 1 year in 101 patients with systemic lupus erythematosus (SLE). METHODS: The primary endpoint was the SLE Disease Activity Index (SLEDAI). The secondary endpoints were the British Isles Lupus Assessment Group index, serum complement activity (CH50) levels, anti-double-stranded DNA (dsDNA) antibody titer, concomitant corticosteroid (CS) dose, and Systemic Lupus International Collaborating Clinics (SLICC) damage index. These variables were compared between the SoC + HCQ (n = 42) and SoC (n = 59) groups. RESULTS: The SLEDAI improved from 2 (0, 6) to 0 (0, 4) in the SoC + HCQ group (P = .038) but significantly deteriorated from 1 (0, 4) to 2 (0, 8) in the SoC group (P = .033). CH50, anti-dsDNA antibody titer, concomitant CS dose, and SLICC damage index did not significantly change. The increase in the SLEDAI and concomitant CS dose after 1 year were all significantly greater in the SoC group, and the proportion of patients with SLEDAI flare was significantly lower in the SoC + HCQ group (SoC + HCQ: 4.76% vs SoC: 25.4%, P = .006). Univariate logistic regression analyses identified HCQ as a predictive factor for no SLEDAI flare (P = .003, odds ratio 6.81, 95% confidence interval 1.77-45.00). CONCLUSIONS: The use of HCQ effectively improved SLEDAI scores and was a predictive factor for the prevention of SLEDAI flare. Therefore, HCQ may be considered a potential mainstay of maintenance therapy.