0
Correspondence |

Community-Acquired Pneumonia: Diagnostic vs Prognostic Significance of the Platelet Count FREE TO VIEW

Burke A. Cunha, MD, FCCP; Jean E. Hage, MD
Author and Funding Information

From the Infectious Disease Division, Winthrop-University Hospital, and State University of New York School of Medicine Stony Brook.

Correspondence to: Burke A. Cunha, MD, FCCP, Infectious Disease Division, Winthrop-University Hospital, 259 First St, Mineola, NY 11501.


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 (http://www.chestpubs.org/site/misc/reprints.xhtml).


© 2011 American College of Chest Physicians


Chest. 2011;139(5):1255-1256. doi:10.1378/chest.10-3146
Text Size: A A A
Published online

To the Editor:

We read with interest the recent report in CHEST by Mirsaeidi et al1 (February 2010) and later discussion by Georges et al2 (November 2010) regarding the prognostic significance of platelet counts in patients with severe community-acquired pneumonia (CAP) requiring hospitalization and ICU admission. However, we are not at all convinced that the platelet count alone is a prognostic indicator in adults hospitalized with severe CAP. In both pieces, information was lacking regarding pathogen distribution, a key determinant of the platelet count.3 Because thrombocytopenia is not an acute-phase reactant, it cannot be said that thrombocytopenia with severe CAP is an indicator of severity and, thereby, is indirectly related to prognosis.3 Any CAP pathogen may present as severe CAP, depending on the cardiopulmonary and immune status of the host. Severity of CAP is largely related to these factors rather than to pathogen virulence per se. Other things being equal, Streptococcus pneumoniae is more virulent than Moraxella catarrhalis. M catarrhalis may present as severe CAP requiring hospitalization and ventilator support in a patient with borderline cardiopulmonary function. Similarly, the nonsevere bacteremic S pneumoniae form of CAP is common in patients with good cardiopulmonary function and intact humoral immunity.4 Unfortunately, specific microbiologic and host-factor data were not included in either report.1,2

However, thrombocytopenia or thrombocytosis may be associated with various CAP pathogens and may have more diagnostic than prognostic significance in adults with severe CAP. CAP pathogens that may be accompanied by thrombocytosis include Q fever and Mycoplasma pneumoniae. CAP pathogens that may be associated with thrombocytopenia include cytomegalovirus, human parainfluenza virus type 3, 2009 influenza A(H1N1), influenza A(H5N1), severe ARDS, Hantavirus pulmonary syndrome, and so forth. Thrombocytopenia is rarely associated with bacterial CAPs but may occur rarely with psittacosis CAP5 (Table 1). If thrombocytopenia is present with bacterial CAP, clinicians should look for an alternate explanation (eg, drug induced), or it may represent a complication (eg, hemolytic uremic syndrome). In normal hosts, most CAP pathogens are not associated with either thrombocytopenia or thrombocytosis. Normal platelet counts are the rule among typical CAP pathogens, such as S pneumoniae, Haemophilus influenzae, and M catarrhalis, as well as among atypical CAP pathogens, such as Legionella species, Chlamydia pneumoniae, and Francisella tularensis.5

Table Graphic Jump Location
Table 1 —Thrombocytopenia or Thrombocytosis in Adults Hospitalized With Severe Community-Acquired Pneumonia
a 

Excluding hemolytic uremic syndrome or hyposplenemia/asplenia.

b 

Platelet count usually normal.

c 

Excluding cases with thrombotic thrombocytopenic purpura or hemolytic uremic syndrome.

In the absence of details on cardiopulmonary and humoral immune function as well as specific pathogen data, the platelet count is necessarily an imprecise prognostic indicator.3 In immunocompetent adults, it would seem that thrombocytopenia and thrombocytosis, rather than having prognostic significance, may be more important diagnostically in suggesting a specific CAP pathogen.

Mirsaeidi M, Peyrani P, Aliberti S, et al. Thrombocytopenia and thrombocytosis at time of hospitalization predict mortality in patients with community-acquired pneumonia. Chest. 2010;1372:416-420. [CrossRef] [PubMed]
 
Georges H, Brogly N, Olive D, Leroy O. Thrombocytosis in patients with severe community-acquired pneumonia. Chest. 2010;1385:1279. [CrossRef] [PubMed]
 
Brogly N, Devos P, Boussekey N, Georges H, Chiche A, Leroy O. Impact of thrombocytopenia on outcome of patients admitted to ICU for severe community-acquired pneumonia. J Infect. 2007;552:136-140. [CrossRef] [PubMed]
 
Cunha BA.Cunha BA. Severe community acquired pneumonia. Infectious Diseases in Critical Care Medicine. 2010;3rd ed New York, NY Informa Healthcare:164-177
 
Cunha BA. Pneumonia Essentials. 2010;2nd ed Sudbury, MA Jones & Bartlett:8-88
 

Figures

Tables

Table Graphic Jump Location
Table 1 —Thrombocytopenia or Thrombocytosis in Adults Hospitalized With Severe Community-Acquired Pneumonia
a 

Excluding hemolytic uremic syndrome or hyposplenemia/asplenia.

b 

Platelet count usually normal.

c 

Excluding cases with thrombotic thrombocytopenic purpura or hemolytic uremic syndrome.

References

Mirsaeidi M, Peyrani P, Aliberti S, et al. Thrombocytopenia and thrombocytosis at time of hospitalization predict mortality in patients with community-acquired pneumonia. Chest. 2010;1372:416-420. [CrossRef] [PubMed]
 
Georges H, Brogly N, Olive D, Leroy O. Thrombocytosis in patients with severe community-acquired pneumonia. Chest. 2010;1385:1279. [CrossRef] [PubMed]
 
Brogly N, Devos P, Boussekey N, Georges H, Chiche A, Leroy O. Impact of thrombocytopenia on outcome of patients admitted to ICU for severe community-acquired pneumonia. J Infect. 2007;552:136-140. [CrossRef] [PubMed]
 
Cunha BA.Cunha BA. Severe community acquired pneumonia. Infectious Diseases in Critical Care Medicine. 2010;3rd ed New York, NY Informa Healthcare:164-177
 
Cunha BA. Pneumonia Essentials. 2010;2nd ed Sudbury, MA Jones & Bartlett:8-88
 
NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging & repositioning the boxes below.

  • CHEST Journal
    Print ISSN: 0012-3692
    Online ISSN: 1931-3543