Clinical trials in allergic conjunctivits: a systematic review

P>Background: Ocular allergy represents one of the most common conditions encountered by allergists and ophthalmologists. However, there is wide variability of study designs in clinical trials of allergic conjunctivitis, which results in conflicting evidence on their optimal management. We conducted a systematic review of clinical trials to critically evaluate their quality and to highlight biases to be avoided in future clinical research in ocular allergy. Methods: Clinical trials in allergic conjunctivitis performed since 1965 were retrieved, and data on patients, interventions, comparison of interventions, and outcomes were extracted. Four authors independently assessed articles for inclusion in the systematic review and assessed trials' quality using the Jadad scale. Results: Three hundred and sixty-two trials were included in the study. Only a minority of trials fulfilled all the criteria of proper clinical trial design. In most of the studies, there was a very limited use of objective (quantifiable) parameters for both patients' selection and evaluation of drug efficacy and safety. Several outcomes of primary importance, such as disease relapses and recurrence rate, were omitted in clinical trials of allergic conjunctivitis. Conclusions: Evidence coming out of clinical trials in ocular allergy is limited, and this affects the strength of recommendations to health care providers and policy makers for optimal management. Standardized diagnostic criteria for patient selection and quantifiable primary outcomes are recommended to improve the design of future clinical trials in allergic conjunctivitis.