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Pulmonary EmbolismPulmonary Embolism: A Monday Effect?: Weekend Effect or Monday Effect? FREE TO VIEW

Philippe Girard, MD, FCCP; Guy Meyer, MD; Patrick Mismetti, MD, PhD
Author and Funding Information

From the Département Thoracique (Dr Girard), Institut Mutualiste Montsouris; the Service de Pneumologie et Soins Intensifs (Dr Meyer), Hôpital Européen Georges Pompidou; and the Unité de Pharmacologie Clinique (Dr Mismetti), CHU de Saint Etienne.

Correspondence to: Philippe Girard, MD, FCCP, Département Thoracique, Institut Mutualiste Montsouris, 42 boulevard Jourdan, 75014, Paris, France; e-mail: philippe.girard@imm.fr


Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.


Chest. 2012;142(4):1073. doi:10.1378/chest.12-1262
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To the Editor:

The thought-provoking study by Nanchal et al1 in CHEST (September 2012) shows that patients admitted to the hospital with a principal diagnosis of pulmonary embolism (PE) during weekends have a significantly higher risk of in-hospital death than those admitted on weekdays (OR, 1.17; 95% CI, 1.11-1.22). The authors suggest that delayed access to inferior vena cava (IVC) filters during weekends might explain this finding. We believe that alternative interpretations merit consideration.

As the authors rightly point out, weekend admissions represent only 21% of all admissions, instead of 28.5% (two out of seven). A simple and plausible interpretation for this finding is a selection bias: Some patients with the least severe clinical forms of PE delay the diagnostic workup (and eventual admission) up to the next working day, whereas patients with severe PEs cannot and do not. The significantly higher rate of severe PEs among weekend admissions (2.8% vs 2.3%, P < .05) supports this interpretation. Interestingly, if such a bias does exist, Mondays should be associated with the highest absolute number of admissions and the lowest death rate of the week, which could be called a “Monday effect.” Could the authors provide this information?

The authors also suggest that delayed IVC filter placements could explain a higher death rate. However, it is far from established that filters, let alone the “timeliness” of filter placement, have an impact on mortality.2-5 Furthermore, as compared with European studies, the overall filter placement rate in this study (13.6%) is disturbingly high. In the Computerized Registry of Patients With VTE (RIETE), a mainly European database, only 2% of patients with VTE received an IVC filter as part of their initial treatment.3 The only two recommended indications for filter placement in patients with PE (ie, contraindications to curative anticoagulation and PE despite adequate anticoagulation)4 are unlikely to be more frequent in the United States than in Europe. Therefore, in the study by Nanchal et al,1 if a substantial proportion of the indications for filter placement in the population were questionable (eg, IVC filters in addition to anticoagulants4), the prognostic impact of delayed placements would appear even more questionable.

The increased mortality rate reported by Nanchal et al1 among weekend admissions for PE may represent real excess deaths. But more convincing arguments are needed to rule out a mere selection bias. And without precise information regarding the indications for filter placement and concurrent anticoagulant use, the timing of IVC filter insertions cannot be regarded as a reliable marker of the quality of care in patients with PE.

Nanchal R, Kumar G, Taneja A, et al;; from the Milwaukee Initiative in Critical Care Outcomes Research (MICCOR) Group of Investigators from the Milwaukee Initiative in Critical Care Outcomes Research (MICCOR) Group of Investigators. Pulmonary embolism: the weekend effect. Chest. 2012;142(3):690-696. [PubMed] [CrossRef]
 
Decousus H, Leizorovicz A, Parent F, et al. A clinical trial of vena caval filters in the prevention of pulmonary embolism in patients with proximal deep-vein thrombosis. Prévention du Risque d’Embolie Pulmonaire par Interruption Cave Study Group. N Engl J Med. 1998;338(7):409-415.
 
Monreal M, Falgá C, Valdés M, et al;; RIETE Investigators RIETE Investigators. Fatal pulmonary embolism and fatal bleeding in cancer patients with venous thromboembolism: findings from the RIETE registry. J Thromb Haemost. 2006;4(9):1950-1956.
 
Kearon C, Akl EA, Comerota AJ, et al. Antithrombotic therapy for VTE disease: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines 2010;141(2):e419S-e494S.
 
Spencer FA, Bates SM, Goldberg RJ, et al. A population-based study of inferior vena cava filters in patients with acute venous thromboembolism. Arch Intern Med. 2010;170(16):1456-1462.
 

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References

Nanchal R, Kumar G, Taneja A, et al;; from the Milwaukee Initiative in Critical Care Outcomes Research (MICCOR) Group of Investigators from the Milwaukee Initiative in Critical Care Outcomes Research (MICCOR) Group of Investigators. Pulmonary embolism: the weekend effect. Chest. 2012;142(3):690-696. [PubMed] [CrossRef]
 
Decousus H, Leizorovicz A, Parent F, et al. A clinical trial of vena caval filters in the prevention of pulmonary embolism in patients with proximal deep-vein thrombosis. Prévention du Risque d’Embolie Pulmonaire par Interruption Cave Study Group. N Engl J Med. 1998;338(7):409-415.
 
Monreal M, Falgá C, Valdés M, et al;; RIETE Investigators RIETE Investigators. Fatal pulmonary embolism and fatal bleeding in cancer patients with venous thromboembolism: findings from the RIETE registry. J Thromb Haemost. 2006;4(9):1950-1956.
 
Kearon C, Akl EA, Comerota AJ, et al. Antithrombotic therapy for VTE disease: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines 2010;141(2):e419S-e494S.
 
Spencer FA, Bates SM, Goldberg RJ, et al. A population-based study of inferior vena cava filters in patients with acute venous thromboembolism. Arch Intern Med. 2010;170(16):1456-1462.
 
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