The Committee’s Concerns with Informed
Consent in the Thiazolidinedione Intervention
with Vitamin D Evaluation (TIDE) Triala,b
1. Study Title
• The study title does not provide an accurate description of the study. It describes the study as a cardiovascular endpoint trial without referring to cardiovascular disease, and it does not mention that rosiglitazone is the primary source of cardiovascular concern in the study.
2. Discussion of the Purpose of the Study
• There is no clear statement of the purpose of the study, and the emphasis in the consent form is shifted away from the cardiovascular risks by the extent of discussion of other aspects of the study. For example, acute myocardial infarction is mentioned only 5 times, whereas cancer and Vitamin D are mentioned 4 and 18 times, respectively.
• Multiple unrelated potential side effects are lumped together (for example, it refers to heart attack, stroke, death, broken bone, and cancers as “diseases”).
• Rosiglitazone and pioglitazone are discussed together, which could be interpreted to mean that current evidence suggests that they pose the same risks. There is no clear statement indicating that Food and Drug Administration (FDA) is not concerned about cardiovascular effects with pioglitazone.
• The form does not highlight that the association between vitamin D and cancer was weak.
• It is not made clear that the inclusion of a Vitamin D arm in the study is not relevant to the reason study was required (that is, concerns about the adverse cardiovascular effects of rosiglitazone), and the discussion about Vitamin D and cancer introduces confusion and could be distracting.
• There is no mention that the purpose of the trial was to establish whether or not there is harm definitively, and the wording does not make clear that there is conflicting evidence about whether thiazolidinedione or Vitamin D helps or harms.
• The fact that the previous data suggest opposing results is not made clear.
• There is no mention that GlaxoSmithKline was ordered by FDA to do the study.