Long-term response to hydroxychloroquine in patients with discoid lupus erythematosus

Background The recommended first-line oral therapy for discoid lupus erythematosus (DLE) is the antimalarial hydroxychloroquine. To the best of our knowledge, there is no published information regarding the long-term (i.e. >6 months) response of DLE to hydroxychloroquine in clinical practice. Objectives To describe the long-term clinical response of DLE to hydroxychloroquine after 6 months of use. Methods A multicentre retrospective cohort study was conducted in patients with DLE who had received treatment with hydroxychloroquine. All patients were recruited and interviewed by a single investigator and response to hydroxychloroquine assessed by the same individual through a retrospective review of case notes using a specified protocol. Results A total of 200 patients with DLE were recruited (F:M=4:1) with a median age at diagnosis of 40 years (range 16-81) and median follow-up of 8 years (range 0 center dot 5-37). An adequate clinical response to hydroxychloroquine was recorded in 91 patients (45 center dot 5%) but nonresponse occurred in 85 patients (425%). The remainder of patients either had partial response or withdrew from therapy due to toxicity or were unclassifiable. Importantly, of those individuals that did respond to hydroxychloroquine within the first 6 months of use, almost one in five eventually lost their response, despite continued administration, after a median interval of 2 years. These patients often regained disease control if treated with a combination of hydroxychloroquine and mepacrine. Of those that did not respond to hydroxychloroquine within the first 6 months of use, almost one in 10 became eventual responders either after continued administration for up to 2 years or when rechallenged on hydroxychloroquine. The remaining nonresponders relied frequently on oral corticosteroid. Conclusions In this cohort of patients with DLE, long-term clinical response to hydroxychloroquine occurred in less than 50% of patients. Nonresponders to hydroxychloroquine frequently required oral steroid to achieve disease control. These findings merit further investigation through a multicentre prospective study using a validated disease activity measure.