Abstract
BackgroundThe recommended first-line therapy of chronic urticaria is second-generation antihistamines, but the modalities of treatment remains unclear. Numerous recommendations with heterogeneous conclusions have been published. We wondered whether such heterogeneous conclusions were linked to the quality of published studies and their reporting.ObjectiveTo review the study design and quality of reporting of randomized control trials investigating pharmacological treatment of autoimmune or idiopathic chronic urticaria.Methodology/Principal FindingsMEDLINE and EMBASE were searched for pharmacological randomized controlled trials involving patients with chronic autoimmune or idiopathic urticaria, with the main outcome being treatment efficacy. Data were collected on general characteristics of the studies, internal validity, studied treatments, design of the trial, outcome measures and “spin” strategy in interpreting results. Spin was defined as use of specific reporting strategies to highlight that the experimental treatment is beneficial, despite statistically nonsignificant results. We evaluated 52 articles that met our criteria. Patients were reported as blinded in 42 articles (81%) and the outcome assessor was blinded in 37 (71%). A placebo was the only comparator in 13 (25%) studies. The study duration was <8 weeks in 39 articles (75%), with no follow-up after discontinuation of treatment in 37 (71%). In 4 articles (8%), blinding was clear because they described blinding of the outcome assessor, the treatment was not recognizable (identical or double-dummy) or had no major secondary effects, and computed randomization was centralized. The primary outcome was specified in 33 articles (63%) and was a score in 31. In total, 15 different scores were used. A spin strategy was used for 10 of 12 studies with a nonsignificant primary outcome.ConclusionFor establishing guidelines in treatment of chronic urticaria, studies should focus on choosing clinically relevant and reproducible primary outcomes, long-term follow-up, limited use of placebo and avoiding spin strategies.
Highlights
Chronic urticaria, idiopathic or autoimmune, is a common disease affecting 0.5% to 1% of individuals
Second-generation H1-antihistamines are recommended as first-line therapy; the choice and doses of antihistamines and associated drugs are not specified
Data were extracted on the definition of urticaria, etiology, duration, severity and inclusion and exclusion criteria; on internal validity, including randomization method, blinding of patients and outcome assessors, possible doubt on blinding linked to side effects, intention-to-treat analysis, number of drop-outs, and reference to the CONSORT statement; on treatments, including the name of the investigated molecules and the use of a placebo; on the design of the trial, including parallel or cross-over status, sample size calculation, number of arms, study duration, and duration of follow-up after the discontinuation of the treatment; and on outcome measures, including assessment of efficacy and whether the primary outcome was mentioned
Summary
To review the study design and quality of reporting of randomized control trials investigating pharmacological treatment of autoimmune or idiopathic chronic urticaria. Methodology/Principal Findings: MEDLINE and EMBASE were searched for pharmacological randomized controlled trials involving patients with chronic autoimmune or idiopathic urticaria, with the main outcome being treatment efficacy. Spin was defined as use of specific reporting strategies to highlight that the experimental treatment is beneficial, despite statistically nonsignificant results. Patients were reported as blinded in 42 articles (81%) and the outcome assessor was blinded in 37 (71%). The primary outcome was specified in 33 articles (63%) and was a score in 31. A spin strategy was used for 10 of 12 studies with a nonsignificant primary outcome
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