Enrollment with and without exception from informed consent in a pilot trial of tranexamic acid in children with hemorrhagic injuries

BACKGROUND

Federal exception from informed consent (EFIC) procedures allow studies to enroll patients with time-sensitive, life-threatening conditions when written consent is not feasible. Our objective was to compare enrollment rates with and without EFIC in a trial of tranexamic acid (TXA) for children with hemorrhagic injuries.

METHODS

We conducted a four-center randomized controlled pilot and feasibility trial evaluating TXA in children with severe hemorrhagic brain and/or torso injuries. We initiated the trial enrolling patients without EFIC. After 3 months of enrollment, we met our a priori futility threshold and paused the trial to incorporate EFIC procedures and obtain regulatory approval. We then restarted the trial allowing EFIC if the guardian was unable to provide timely written consent. We used descriptive statistics to compare characteristics of eligible patients approached with and without EFIC procedures. We also calculated the time delay to restart the trial using EFIC.

RESULTS

We enrolled one of 15 (6.7%) eligible patients (0.17 per site per month) prior to using EFIC procedures. Of the 14 missed eligible patients, seven (50%) were not enrolled because guardians were not present or were injured and unable to provide written consent. After obtaining approval for EFIC, we enrolled 30 of 48 (62.5%) eligible patients (1.34 per site per month). Of these 30 patients, 22 (73.3%) were enrolled with EFIC. Of the 22, no guardians refused written consent after randomization. There were no significant differences in the eligibility rate and patient characteristics enrolled with and without EFIC procedures. Across all sites, the mean delay to restart the trial using EFIC procedures was 12 months.

CONCLUSIONS

In a multicenter trial of severely injured children, the use of EFIC procedures greatly increased the enrollment rate and was well accepted by guardians. Initiating the trial without EFIC procedures led to a significant delay in enrollment.

Traumatic injury clinical trial evaluating tranexamic acid in children (TIC-TOC): study protocol for a pilot randomized controlled trial

Background

Trauma is the leading cause of morbidity and mortality in children in the United States. The antifibrinolytic drug tranexamic acid (TXA) improves survival in adults with traumatic hemorrhage, however, the drug has not been evaluated in a clinical trial in severely injured children. We designed the Traumatic Injury Clinical Trial Evaluating Tranexamic Acid in Children (TIC-TOC) trial to evaluate the feasibility of conducting a confirmatory clinical trial that evaluates the effects of TXA in children with severe trauma and hemorrhagic injuries.

Methods

Children with severe trauma and evidence of hemorrhagic torso or brain injuries will be randomized to one of three arms: (1) TXA dose A (15 mg/kg bolus dose over 20 min, followed by 2 mg/kg/hr infusion over 8 h), (2) TXA dose B (30 mg/kg bolus dose over 20 min, followed by 4 mg/kg/hr infusion over 8 h), or (3) placebo. We will use permuted-block randomization by injury type: hemorrhagic brain injury, hemorrhagic torso injury, and combined hemorrhagic brain and torso injury. The trial will be conducted at four pediatric Level I trauma centers. We will collect the following outcome measures: global functioning as measured by the Pediatric Quality of Life (PedsQL) and Pediatric Glasgow Outcome Scale Extended (GOS-E Peds), working memory (digit span test), total amount of blood products transfused in the initial 48 h, intracranial hemorrhage progression at 24 h, coagulation biomarkers, and adverse events (specifically thromboembolic events and seizures).

Discussion

This multicenter trial will provide important preliminary data and assess the feasibility of conducting a confirmatory clinical trial that evaluates the benefits of TXA in children with severe trauma and hemorrhagic injuries to the torso and/or brain.

Trial registration

ClinicalTrials.gov registration number: NCT02840097. Registered on 14 July 2016.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2974-z) contains supplementary material, which is available to authorized users.

Matrix metalloproteinase (MMP)-1 and MMP-3 induce macrophage MMP-9: evidence for the role of TNF-alpha and cyclooxygenase-2

Matrix metalloproteinase (MMP)-9 (gelatinase B) participates in a variety of diverse physiologic and pathologic processes. We recently characterized a cyclooxygenase-2 (COX-2)-->PGE(2)-->EP4 receptor axis that regulates macrophage MMP-9 expression. In the present studies, we determined whether MMPs, commonly found in inflamed and neoplastic tissues, regulate this prostanoid-EP receptor axis leading to enhanced MMP-9 expression. Results demonstrate that exposure of murine peritoneal macrophages and RAW264.7 macrophages to MMP-1 (collagenase-1) or MMP-3 (stromelysin-1) lead to a marked increase in COX-2 expression, PGE(2) secretion, and subsequent induction of MMP-9 expression. Proteinase-induced MMP-9 expression was blocked in macrophages preincubated with the selective COX-2 inhibitor celecoxib or transfected with COX-2 small interfering RNA (siRNA). Likewise, proteinase-induced MMP-9 was blocked in macrophages preincubated with the EP4 antagonist ONO-AE3-208 or transfected with EP4 siRNA. Exposure of macrophages to MMP-1 and MMP-3 triggered the rapid release of TNF-alpha, which was blocked by MMP inhibitors. Furthermore, both COX-2 and MMP-9 expression were inhibited in macrophages preincubated with anti-TNF-alpha IgG or transfected with TNF-alpha siRNA. Thus, proteinase-induced MMP-9 expression by macrophages is dependent on the release of TNF-alpha, induction of COX-2 expression, and PGE(2) engagement of EP4. The ability of MMP-1 and MMP-3 to regulate macrophage secretion of PGE(2) and expression of MMP-9 defines a nexus between MMPs and prostanoids that is likely to play a role in the pathogenesis of chronic inflammatory diseases and cancer. These data also suggest that this nexus is targetable utilizing anti-TNF-alpha therapies and/or selective EP4 antagonists.