Three cases of heparin-induced thrombocytopenia associated with polytrauma

Characterization of platelet concentrations and evaluation of risk factors for thrombocytopenia following traumatic injury

Introduction

Thrombocytopenia is common in critically ill trauma patients and can lead to potentially broad differentials, including major bleeding, hemodilution, extracorporeal circuit losses, heparin-induced thrombocytopenia, and more. Understanding the normal time course of platelet decline and recovery may delineate thrombocytopenia(HIT) secondary to traumatic injury versus other inciting factors.

Methods

This retrospective study included trauma patients admitted over a 1-year period. The primary aim was characterizing the effect of trauma on platelet concentration and thrombocytopenia incidence in the first 30 days following injury. Thrombocytopenia was defined as platelet concentration <150 × 109/L. A secondary aim was evaluating significant factors contributing to thrombocytopenia.

Results

A total of 225 patients were included. Thrombocytopenia occurred in 67.3% of patients, and a platelet decline of 50% or greater occurred in 44%. Decrease in platelet concentration was significant from day 1 to day 4 (mean ± SD, 232 ± 86 vs 142 ± 76 × 109/L; p = .001). Platelets recovered to baseline on day 8 and peaked on day 16. Packed red blood cell or platelet transfusion, continuous renal replacement therapy, and acute liver injury independently predicted a ≥50% platelet decrease. HIT was not diagnosed in any patients.

Conclusion

Platelet nadir likely occurs approximately 4 days after injury and recovers relatively quickly thereafter. More studies are needed to evaluate the magnitude of effect on thrombocytopenia by factors beyond trauma.

Comparative effectiveness and safety of anticoagulants for the treatment of heparin-induced thrombocytopenia

BACKGROUND

The effectiveness and safety of non-heparin anticoagulants for the treatment of heparin-induced thrombocytopenia (HIT) are not fully established, and the optimal treatment strategy is unknown. In a systematic review and meta-analysis, we aimed to determine precise rates of platelet recovery, new or progressive thromboembolism (TE), major bleeding, and death for all non-heparin anticoagulants and to study potential sources of variability.

METHODS

Following a detailed protocol (PROSPERO: CRD42020219027), EMBASE and Medline were searched for all studies reporting clinical outcomes of patients treated with non-heparin anticoagulants (argatroban, danaparoid, fondaparinux, direct oral anticoagulants [DOAC], bivalirudin, and other hirudins) for acute HIT. Proportions of patients with the outcomes of interest were pooled using a random-effects model for each drug. The influence of the patient population, the diagnostic test used, the study design, and the type of article was assessed.

RESULTS

Out of 3194 articles screened, 92 studies with 119 treatment groups describing 4698 patients were included. The pooled rates of platelet recovery ranged from 74% (bivalirudin) to 99% (fondaparinux), TE from 1% (fondaparinux) to 7% (danaparoid), major bleeding from 1% (DOAC) to 14% (bivalirudin), and death from 7% (fondaparinux) to 19% (bivalirudin). Confidence intervals were mostly overlapping, and results were not influenced by patient population, diagnostic test used, study design, or type of article.

DISCUSSION

Effectiveness and safety outcomes were similar among various anticoagulants, and significant factors affecting these outcomes were not identified. These findings support fondaparinux and DOACs as viable alternatives to conventional anticoagulants for treatment of acute HIT in clinical practice.