Bias and unclear outcomes in clinical trials of diabetic retinopathy: a cross-sectional analysis of literature

Abstract

BACKGROUND: Clinical trials are well-designed papers that aim to answer questions in the real world. However, sometimes they present missing, dubious and unclear outcomes that make it difficult to apply in practice. OBJECTIVE: The objective of this work is to evaluate the way and the frequency with which the outcomes in randomized clinical trials of intervention in diabetic retinopathy can be presented in an unclear way to readers. Make an analysis of how these dubious presentations can lead to misinterpretations, why this happens and how they can be remedied. METHODS AND MATERIALS: We conducted a search for RCT about DR intervention in PubMed published over the past five years. RESULTS: Seventy RCT were included, 27 in peripheral diabetic retinopathy (PDR) and 43 in diabetic macular edema (DME). In the DME group we found 25.6% reporting and publication bias; 34.9% subjective outcomes, 44.1% presented a lack of presentation of the baseline and 51.1% underreporting adverse events. In the PDR group we found 29.6% reporting and publication bias; 44.4% subjective outcomes, 14.8% presented a lack of presentation of the baseline and 62.9% underreporting adverse events. CONCLUSION: In addition to the result bias, we found other forms of publication of unclear outcomes in RCT on DR. Most of them occurred due to disrespect for CONSORT parameters. The reader must be attentive to recognize them and know how they can influence the interpretation of the data.

Keywords

• Outcome Bias. Diabetic Retinopathy. Diabetic Macular Edema. Evidence based medicine. Literature review.