[Disclosure of sources of funding in biomedical journals. Descriptive study of four Spanish publications]

The source of research funding can result in bias, and its disclosure is essential in the publication of results. The aim of the study is to identify the frequency and type of sources of funding in the articles published by four Spanish biomedical journals published in Spanish.

The frequency and type of financial disclosures in the articles published during 2012 in the ordinary numbers of Atención Primaria, Medicina Clínica, Revista Clínica Española and Revista Española de Cardiología were analyzed. Articles described as "Editorial", "Original article", "Consensus Document", "Review" and "Special Article" were considered. It was decided in each case whether or not the article included any funding disclosure and the type of the declared funding (public or private).

Four hundred and twelve publications were analyzed. In 32.5% there was disclosure of funding: 38% in Atención Primaria, 27% in Medicina Clínica, 15% in Revista Clínica Española and 45% in Revista Española de Cardiología. By type of articles, 47% of original articles, 44% of consensus documents, 21% of reviews, 14% of special articles and 8% of editorials had a funding source. In 51.5% of the cases, funding was exclusively public, in 36.5% exclusively private and in 10% mixed.

There is considerable variability in the disclosure of funding sources in articles appearing in these four Spanish biomedical journals. It would be necessary to improve the disclosure requirements of sources of funding, making them uniform, clear and transparent.