Adherence to clinical trial registration in countries of Latin America and the Caribbean, 2015.

Objective: To determine the prevalence of clinical trial registration in the International Clinical Trial Registry Platform (ICTRP) for studies from Latin America and the Caribbean (LAC) and to identify the key characteristics that lead to prospective and retrospective registration.

Methods: A cross-sectional study identified published, clinical trial studies through a search of PubMed, LILACS (Latin American and Caribbean Center on Health Sciences Information), and the Cochrane Central Register of Controlled Trials. Studies were included if published on 1 January - 31 December 2015, at least one author was affiliated with at least one LAC country, the clinical trial was conducted in at least one LAC site, and the full text of the article was available. A manual search of reference lists was also conducted. ICTRP registration information and key trial characteristics were compared.

Results: Of 1 502 CT references that met inclusion criteria, 297 were randomly-selected, 90.9% of which were published in English, 65% from Brazil, and 76.8% had a LAC author as the first author. The proportion of CT registered in the ICTRP was 59.9 %, of which 51.7% were registered prospectively. Clinicaltrials.gov was most frequently used registry (84.8%), followed by the and the . Key characteristics that favored registration were being in study phase 3 or 4 or being a multi-center study. Data was compared to a similar study from 2013 that reported a registration rate of only 19.8%.

Conclusions: Registration adherence and prospective registration have increased in LAC in recent years, but the proportion of unregistered CT remains high. While there are still many challenges to overcome, the adherence strategies implemented in recent years have proven effective.