Quality of clinical studies present in the package inserts of coagulation factors used in the treatment of hemophilia

OBJECTIVE: To identify and analyze the quality of scientific evidence from clinical efficacy studies present in the package inserts of coagulation factors, used in the treatment of hemophilia A and B. METHODS: Documentary study developed in two stages. The first stage consisted of identifying the medicine packages inserts electronically registered in the Brazilian Health Regulatory Agency, and analyzing the availability of the bibliographic references cited therein. This analysis was conducted in the PubMed, SciELO, Google Scholar, and Web of Science databases. The second step was the analysis of the methodological quality of the efficacy studies. Two trained researchers used the Cochrane Collaboration Risk of Bias version 5.1.0 tools for methodological quality analysis, and Review Manager 5.4 software to generate the risk of bias graph. RESULTS: Of the 17 medicines listed, 7 had referenced package inserts. Of these, 10 studies were eligible for analysis of methodological quality. More than half of the analyzed studies did not control for selection, performance, and detection bias. A total of 100% controlled attrition and reporting biases, and 50% had a high risk of conflict of interest. CONCLUSION: The biases present are significant and may have influenced the overestimation of the effects of the outcomes of each of the studies.