Phase 4 Interventional studies from Spain (completed before Jan 2011): How many unpublished?

  • Coauthored with Marc Casañas.

Background:

A few days ago we started to analyze data of public clinical trial registries with recruitment centers located in Spain. Analyzing hidden data of research is crucial to determine the influence of publication bias (cherry-picking), if the intended purpose is the correct scientific appraisal of the evidence about the effectiveness and safety of drugs aimed to prevent disease or modify their natural course. Publication bias is also a phenomenon observed in non-pharmacological interventions (e.g., Mediterranean diet, exercise, surgery, other therapies). In this post, we would like specifically to engage others in the analysis of hidden research. Thousands of papers are selectively published by scientific peer-review journals while results of a significant number (over half) of human studies remain secret and hidden from the public eye.

We know already how many of the 329 phase 4 trials registered at ClinicalTrials.gov and located Spain remain unpublished over 4 years after the recruitment of their last patient (i.e., before Jan 2011).

Data is open:

Ramirez, Jorge H; Casañas, Marc (2015): ClinicalTrials.gov – Search Query (July 2, 2015) = Closed Studies | Spain – 5374 studies. figshare.
http://dx.doi.org/10.6084/m9.figshare.1474035
Retrieved 02:46, Jul 12, 2015 (GMT)

https://clinicaltrials.gov/ct2/results/map/click?map.x=405&map.y=135&recr=Closed&type=Intr&phase=3

Search of  Closed Studies   Interventional Studies   Phase 4   Results on Map   ClinicalTrials.gov

Search  of  Closed Studies   Interventional Studies   Phase 4   Results on Map   ClinicalTrials.gov

– Spain: 652 closed studies | phase 4 | interventional studies.

Completed before January 2011 (registry fields: completion date or primary completion date): 329 studies.


Before disclosing the results of our analysis, we would like to ask readers to estimate (or guess) how many of these studies remain unpublished:

The precise estimate will be disclosed soon outside this blog and will be written in Spanish (because the analysis concerns patients recruited in Spain). After the original publication in Spanish, the post will be translated to English and published in this blog.

Description of methods used for the identification of unpublished studies across academic databases.

– Phase 3 trials evaluating drugs & biologicals – studies located in Germany, UK, and France => ~ 50% unpublished

  1 comment for “Phase 4 Interventional studies from Spain (completed before Jan 2011): How many unpublished?

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