Abstract
IMPORTANCE: The first-line treatment for patients with chronic spontaneous urticaria (CSU), which is divided into idiopathic and autoimmune subtypes, consists of H1-antihistamines. However, limited evidence guides the treatment of CSU after maximal therapy with antihistamines fails. Two randomized clinical trials suggest that dapsone may be a successful second-line therapy. OBJECTIVE: To evaluate the efficacy and safety of dapsone therapy in patients with CSU. DESIGN, SETTING, AND PARTICIPANTS: This retrospective medical record review included 79 patients with CSU treated with dapsone who presented to the tertiary care academic medical center at the New York University School of Medicine, New York, New York, from January 1, 2005, through April 15, 2017. Follow-up was completed on February 28, 2018. Data were analyzed from March 1 through May 31, 2018. EXPOSURES: Treatment with oral dapsone for CSU. MAIN OUTCOMES AND MEASURES: Efficacy of dapsone therapy for CSU was evaluated as improvement, complete response, and remission. RESULTS: Seventy-nine patients (65% women; mean [SD] age, 49.8 [16.1] years [range, 20-79 years]) were included in the analysis. Forty-five patients had chronic idiopathic urticaria and 34 had chronic autoimmune urticaria. Improvement in CSU was observed in 62 patients (78%) (36 [80%] with idiopathic and 26 [76%] with autoimmune disease) with dapsone. Mean (SD) time to improvement was 1.1 (1.0) months. A complete response was achieved in 29 (47%) of these 62 patients (16 [44%] with idiopathic and 13 [50%] with autoimmune disease). Mean (SD) time to complete response was 5.2 (5.2) months. Dapsone therapy was tapered in 21 patients after a mean (SD) of 2.4 (2.2) months and discontinued in 18. Ten patients experienced remission with no subsequent flares, even after dapsone therapy was discontinued with follow-up of 0.3 to 10.0 months. Sixteen patients experienced mild adverse effects. Two serious adverse effects were reported. CONCLUSIONS AND RELEVANCE: Results of this study suggest that dapsone is a useful and well-tolerated second-line therapy for patients with CSU in whom antihistamines and other first-line agents have failed.