title: Community-acquired pneumonia as the initial manifestation of serious underlying diseases.
abstract: OBJECTIVE
  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.
  
  
  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.
  
  
  CONCLUSIONS
  In the initial diagnostic workup of patients with community-acquired pneumonia, the possibility of unknown comorbid conditions should be carefully evaluated.
authors.affiliation: Department of Internal Medicine, Hospital Universitari Arnau de Vilanova, Servei de Medicine Interna, Rovira Roure 80, 25198 Lleida, Spain. mfalguera@comll.es
authors.forename: Miquel
authors.initials: M
authors.lastname: Falguera
authors.forename: Mariela
authors.initials: M
authors.lastname: Martín
authors.forename: Agustín
authors.initials: A
authors.lastname: Ruiz-González
authors.forename: Ricard
authors.initials: R
authors.lastname: Pifarré
authors.forename: Mercè
authors.initials: M
authors.lastname: García
mesh_terms: D017714:Community-Acquired Infections / Q000150:complications* / Q000382:microbiology; D015897:Comorbidity; D048909:Diabetes Complications; D005260:Female; D005500:Follow-Up Studies; D015658:HIV Infections / Q000150:complications; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000150:complications; D011014:Pneumonia / Q000150:complications* / Q000382:microbiology; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications