Missingness matters: a secondary analysis of thromboelastography measurements from a recent prehospital randomized tranexamic acid clinical trial

Jack K Donohue; Nidhi Iyanna; John M Lorence; Joshua B Brown; Frances X Guyette; Brian J Eastridge; Raminder Nirula; Gary A Vercruysse; Terence O'Keeffe; Bellal Joseph; Matthew D Neal; Jason L Sperry

doi:10.1136/tsaco-2023-001346

Missingness matters: a secondary analysis of thromboelastography measurements from a recent prehospital randomized tranexamic acid clinical trial

Trauma Surg Acute Care Open. 2024 Feb 17;9(1):e001346. doi: 10.1136/tsaco-2023-001346. eCollection 2024.

Affiliations

¹ Division of Trauma and General Surgery, Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
² Department of Emergency Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
³ Department of Surgery, University of Texas Health San Antonio, San Antonio, Texas, USA.
⁴ Department of Surgery, University of Utah, Salt Lake City, Utah, USA.
⁵ Department of Surgery, University of Arizona, Tucson, Arizona, USA.

Abstract

Background: Tranexamic acid (TXA) has been hypothesized to mitigate coagulopathy in patients after traumatic injury. Despite previous prehospital clinical trials demonstrating a TXA survival benefit, none have demonstrated correlated changes in thromboelastography (TEG) parameters. We sought to analyze if missing TEG data contributed to this paucity of findings.

Methods: We performed a secondary analysis of the Study of Tranexamic Acid During Air Medical and Ground Prehospital Transport Trial. We compared patients that received TEG (YES-TEG) and patients unable to be sampled (NO-TEG) to analyze subgroups in which to investigate TEG differences. TEG parameter differences across TXA intervention arms were assessed within subgroups disproportionately present in the NO-TEG relative to the YES-TEG cohort. Generalized linear models controlling for potential confounders were applied to findings with p<0.10 on univariate analysis.

Results: NO-TEG patients had lower prehospital systolic blood pressure (SBP) (100 (78, 140) vs 125 (88, 147), p<0.01), lower prehospital Glascow Coma Score (14 (3, 15) vs 15 (12, 15), p<0.01), greater rates of prehospital intubation (39.4% vs 24.4%, p<0.01) and greater mortality at 30 days (36.4% vs 6.8%, p<0.01). NO-TEG patients had a greater international normalized ratio relative to the YES-TEG subgroup (1.2 (1.1, 1.5) vs 1.1 (1.0, 1.2), p=0.04). Within a severe prehospital shock cohort (SBP<70), TXA was associated with a significant decrease in clot lysis at 30 min on multivariate analysis (β=-27.6, 95% CI (-51.3 to -3.9), p=0.02).

Conclusions: Missing data, due to the logistical challenges of sampling certain severely injured patients, may be associated with a lack of TEG parameter changes on TXA administration in the primary analysis. Previous demonstration of TXA's survival benefit in patients with severe prehospital shock in tandem with the current findings supports the notion that TXA acts at least partially by improving clot integrity.

Level of evidence: Level II.

Keywords: Multiple Trauma; blood transfusion; thromboelastography; tranexamic acid.

Grants and funding

R35 GM119526/GM/NIGMS NIH HHS/United States