Clinical research study
Community-acquired pneumonia as the initial manifestation of serious underlying diseases

https://doi.org/10.1016/j.amjmed.2005.01.011Get rights and content

Abstract

Purpose

Community-acquired pneumonia is common among patients with coexisting illnesses and it can be the initial manifestation of these comorbid diseases. The objectives of our study were to evaluate the frequency of this association and to analyze whether certain characteristics could predict the presence of unknown comorbid conditions.

Subjects and methods

Over a 5-year period, we prospectively studied 660 consecutive patients with community-acquired pneumonia seen at our institution. In a subgroup of these patients, diagnosis of previously unknown comorbid conditions was established during follow-up. Characteristics of these patients were compared with data from the remaining sample of patients.

Results

Prior underlying diseases were present in 298 (45%) patients. One or more new comorbid conditions were found in 41 (6%), of which diabetes (14 cases), malignancies (12 cases), chronic obstructive pulmonary disease (8 cases), and human immunodeficiency virus (HIV) infection (5 cases) were the most common. In the comparative study, a bacterial etiology, positive blood cultures, and hospitalization were more frequently found (P < 0.05) in patients with new comorbid conditions than atypical microorganisms or viruses, negative blood cultures, or outpatient care.

Conclusion

In the initial diagnostic workup of patients with community-acquired pneumonia, the possibility of unknown comorbid conditions should be carefully evaluated.

Section snippets

Study design and setting

For a 5-year period (January 1998 to December 2002), all patients with community-acquired pneumonia diagnosed at the emergency room of the Arnau de Vilanova Hospital in Lleida (Catalonia, Spain) were included in a prospective study on epidemiologic, clinical, microbiologic, and outcome parameters. This study was examined and approved by the scientific and ethics committees of the institution.

Study and follow-up of patients

On enrollment (first visit), all patients underwent a complete clinical history and physical

Results

We evaluated a total of 726 episodes of community-acquired pneumonia, based on the clinical and radiologic findings at entry. We excluded 66 patients for the following reasons: an erroneous diagnosis of pneumonia (59), recent hospitalization (4), and failure to obtain informed consent.3 In consequence, 660 patients constituted the final study group.

Five-hundred and twenty-nine (80%) were hospitalized and 131 were managed as outpatients. During follow-up, 58 (9%) patients died, all in the

Discussion

This study shows that community-acquired pneumonia can be the first manifestation of previously unknown underlying diseases. Thus, we found 1 or more new serious comorbid conditions in more than 6% of our patients; diabetes mellitus, neoplasm (particularly lung and hematologic malignancies), chronic obstructive pulmonary disease, and HIV infection were the most frequently recognized coexisting illnesses. The detection of unknown comorbid conditions was particularly frequent in patients who had

Acknowledgment

We thank Roman Pallares, MD for his critical review of the manuscript.

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