Symptom-triggered diagnosis in lung transplant recipients: does it underestimate the true venous thromboembolism burden and its consequences?

We read with great interest the insightful article by Kim et al. titled “Risk factors and perioperative complications associated with deep venous thrombosis and pulmonary embolism after lung transplantation” in a recent issue of the Journal of Thoracic Disease (1). The authors conducted a rigorous retrospective analysis of 399 lung transplant recipients, reporting a strikingly high incidence of postoperative deep vein thrombosis (DVT) of 53.6% (214/399 patients). Their data reveal a profoundly increased mortality in patients with DVT compared to those without (33.2% vs. 13.0%, P<0.001), accompanied by significantly higher rates of pulmonary embolism (PE) (22.4% vs. 5.4%), hemothorax/hematoma (50.5% vs. 29.7%), and prolonged hospitalization. Of paramount clinical importance, their multivariate Cox analysis within the DVT cohort demonstrated that mortality was driven by hemorrhagic complications [adjusted hazard ratio (HR) =2.24; 95% confidence interval (CI): 1.32–3.81] rather than by PE itself (adjusted HR =1.12; 95% CI: 0.62–1.99). This finding critically underscores the perilous equilibrium between thrombotic and bleeding risks in this population.

We commend the authors for their valuable contribution. However, the interpretation and generalizability of these pivotal results must be contextualized within a key methodological framework detailed in their paper. The authors state: “Duplex ultrasound or further imaging for DVT was performed only when patients developed clinical symptoms suggestive of venous thrombosis; no routine screening protocol was in place for asymptomatic patients” (1). This symptom-triggered diagnostic strategy is a standard yet potentially limiting approach, as it may systematically fail to detect a clinically silent reservoir of venous thromboembolism (VTE).

The rationale for this concern is twofold

High risk for asymptomatic VTE: post-lung transplant patients frequently experience prolonged immobilization, sedation, central venous catheterization, and a systemic inflammatory state—all factors that elevate thrombotic risk while masking classic symptoms (2,3). Studies in thoracic surgery and intensive care settings found that 7.5–12.1% of patients had DVT detected only through screening, with up to 79% of these being asymptomatic (4). In such high-acuity settings, studies have shown that routine screening uncovers a significant incidence of asymptomatic DVT that would otherwise go undiagnosed (5).

Implications for reported epidemiology and associations

The 53.6% DVT incidence, while remarkably high, may represent an underestimation of the true postoperative burden. This potential under-ascertainment could influence several of the study’s conclusions:

• The identified risk factors for PE (lower extremity DVT, elevated preoperative platelet count) are robust for the symptomatic cohort but may not fully capture the risk profile of the overall VTE population.
• The null association between PE and mortality (HR =1.12; P=0.72) is a crucial finding. One interpretation is that DVT is a marker of overall illness severity. An alternative, non-exclusive explanation is that some patients with undiagnosed (and thus untreated) DVT may have progressed to fatal PE (6), with their outcomes not being attributed to VTE in this analysis. This could bias the observed HR toward the null.

The authors rightly acknowledge this limitation in their discussion. Their work therefore not only highlights a major clinical challenge but also illuminates a significant evidence gap. To advance toward personalized, risk-adapted management, we must first accurately define the scope of the problem. We strongly concur with the need for prospective, multi-center studies that employ protocolized, serial postoperative VTE screening. Such research is essential to establish the true incidence of symptomatic and asymptomatic VTE, to validate risk stratification models in an unbiased cohort, and to provide the foundational evidence for trials assessing optimized prophylactic and therapeutic strategies. The substantial mortality burden associated with this complication, as clearly demonstrated by Kim et al. (1), calls for a more proactive diagnostic paradigm.

Acknowledgments

None.

Footnote

Provenance and Peer Review: This article was a standard submission to the journal. The article did not undergo external peer review.

Funding: None.

Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-1-2549/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

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References

1. Kim NT, Miyashita Y, Kaihou T, et al. Risk factors and perioperative complications associated with deep venous thrombosis and pulmonary embolism after lung transplantation. J Thorac Dis 2025;17:9342-56. [Crossref] [PubMed]
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