Background:

Confidence in the results reported by randomized clinical trials (RCTs) depends mainly on the internal validity of the trial and its conduct, but also on other aspects related to health research such as the complete reporting of conflicts of interest (COI), funding sources and approval by ethics committees. Bias in the study results may arise from any one of these elements. Prior studies have explored the reporting of these items in the medical literature, but there are no reports on RCTs published in Spanish and Latin American journals. This study aimed to evaluate the reporting of COIs, funding sources, and approval by ethics committees of RCTs published in Spanish and Latin American journals in dentistry, geriatrics and neurology.

Methods:

We did a systematic retrospective survey of all RCTs published from 1990 to 2018 in dentistry, neurology, and geriatrics journals published in Spain and Latin America and included in the BADERI database (Iberoamerican journals and trials database by its initials in Spanish). We completed with hand searching. We included RCTs with a recoverable full text published between 1990 and 2018. We extracted data on sources of funding, COI statements, and ethics reviews. The extraction of these items in the RCTs included was done independently by two pairs of reviewers and in parallel for each article, with a third independent reviewer resolving discrepancies. We analysed compliance for each item.

Results:

We identified RCTs in 69 journals from Spain and Latin American countries. Dentistry accounted for 75% (n = 52) of the journals, neurology 20.6% (n = 14), and geriatrics 4.4% (n = 3). Of the total number of RCTs included in this study (n = 392), only 102 (26%) reported the presence or absence of a COI, 103 (26%) studies reported funding, and 43 (36%) included the ethics committee approval.

Conclusions:

RCTs published in the Spanish language in dentistry, neurology, and geriatrics had poor compliance with the reporting of a COI, source of funding, and ethics committee approval. Future research should evaluate the accuracy and completeness of COI statements and their relationship to the funding source and direction of the results.