Clinical trials in medical congresses: a study on conflicts of interest

This article seeks to investigate conflicts of interest involving the presentation of clinical trials in Brazilian congresses of five medical specialties between 2004 and 2018. A total of 407 abstracts in 22 annals were studied. After applying selection criteria, we reached a corpus of 77 essays. A higher frequency of conflicts of interest was found involving essays with drugs for which no generic/similar option was available (p=0.000), and 48% of those with a conflict of interest declared nothing. Favorable results to the test drug occurred in 90.9% of the total of essays, but 48.6% of them lacked the p-value. The most tested therapeutic categories were immunosuppressors and immunomodulators, antidiabetic, and antineoplastic, which, together, amounted to 68.9% of the total of the involved drugs. The results pointed to hidden conflicts of interest, overvaluing of positive results of test drugs, not always with sufficient evidence, and focus of production on high-cost drugs.