A new study has found significant biases in the clinical studies cited in the package inserts of coagulation factors used for treating people with hemophilia in Brazil.

The study, published in Einstein (Sao Paulo), found that 50% of the studies had a high risk of conflict of interest and the same proportion had no control group and did not control for specific biases including selection, performance, and detection.

“Given the budget constraint of the Ministry of Health of Brazil, combined with the high cost of coagulation factors used in the treatment of hemophilia, it is urgent to conduct research for assessing the quality of scientific evidence of phase III clinical studies available in the package inserts of these medicines, as there are many studies in which the scientific bias has been masked by economic interests,” the authors wrote.

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The research team analyzed 17 package inserts of coagulation factors, only 7 of which contained references. There were 10 phase 3 clinical studies analyzed in the second phase of the study, and the authors employed Review Manager 5.4 software to assess the risk of bias.

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In the 50% of studies with a control group, there was no report on the performance or how the randomization and allocation were performed. Half of the studies did not control for selection, performance, or detection bias, and they presented a high risk of conflict of interest. Finally, 10 of the 17 inserts for health professionals did not reference the efficacy studies at all.

All the studies analyzed did control for attrition bias with adequate follow-up, and all patient losses and exclusions were properly justified. In addition, the studies presented a low risk of bias in selective outcome reporting, which ensures there are no deviations in study protocols.

Overall, however, the authors said they obtained “worrying” results regarding the quality of the package inserts and recommend greater rigor in their inspection by regulatory agencies in Brazil.


Araújo YG, Paolinelli JPV, Pichitelli JSD, et al. Quality of clinical studies present in the package inserts of coagulation factors used in the treatment of hemophilia. Einstein (Sao Paulo). Published May 6, 2022. doi:10.31744/einstein_journal/2022AO6859