title: Aetiology and prediction of pneumonia in lower respiratory tract infection in primary care.
abstract: BACKGROUND
  Knowledge of predominant pathogens and their association with outcome are of importance for the management of lower respiratory tract infection (LRTI). As antibiotic therapy is indicated in pneumonia and not in acute bronchitis, a predictor of pneumonia is needed.
  
  
  OBJECTIVE
  To describe the aetiology and outcome of LRTI in adults with pneumonic and adults with non-pneumonic LRTI treated in general practice and to identify predictors of radiographic pneumonia.
  
  
  METHODS
  Prospective, observational study.
  
  
  METHODS
  Forty-two general practices and an outpatient clinic at the Department of Infectious Diseases, Odense University Hospital, Denmark.
  
  
  METHODS
  A total of 364 adults diagnosed with community-acquired LRTI by their GP were studied with chest radiography, vital signs, biochemical markers of inflammation (C-reactive protein [CRP] and leukocyte count), and microbiological examinations. Primary outcome measure was hospitalisation within 4 weeks.
  
  
  RESULTS
  Pneumonia was radiographically verified in 48 of 364 patients (13%). Bacterial infection was seen more often in patients with pneumonia (33% versus 17%, P<0.001), and viral infection more often in non-pneumonic patients (26% versus 13%, P<0.05). Hospitalisation was more common in patients with pneumonia compared to non-pneumonic patients (19 versus 3%, P<0.001); and in patients with pneumococcal infection compared with patients without pneumococcal infection (26 versus 4%, P = 0.001). The positive predictive value of GPs' diagnosis of pneumonia was low (0.23), but the vital signs, CRP, and leukocyte count had comparably low positive predictive values (0.23-0.30).
  
  
  CONCLUSIONS
  Streptococcus pneumoniae was the most common bacterial pathogen. The risk of hospitalisation was highest among patients with pneumonia or pneumococcal infection; this emphasises the importance of coverage of S. pneumoniae when treatment is indicated. CRP should not be introduced for diagnosis of radiographic pneumonia in general practice before its use has been investigated in prospective, controlled intervention trials using CRP-guided treatment algorithms.
authors.affiliation: Department of Infectious Diseases C, Odense University Hospital, Denmark. anette.holm@ouh.regionsyddanmark.dk
authors.forename: Anette
authors.initials: A
authors.lastname: Holm
authors.forename: Joergen
authors.initials: J
authors.lastname: Nexoe
authors.forename: Lene A
authors.initials: LA
authors.lastname: Bistrup
authors.forename: Svend S
authors.initials: SS
authors.lastname: Pedersen
authors.forename: Niels
authors.initials: N
authors.lastname: Obel
authors.forename: Lars P
authors.initials: LP
authors.lastname: Nielsen
authors.forename: Court
authors.initials: C
authors.lastname: Pedersen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002097:C-Reactive Protein / Q000378:metabolism; D005260:Female; D006801:Humans; D007251:Influenza, Human / Q000175:diagnosis* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D009175:Mycoplasma Infections / Q000175:diagnosis* / Q000209:etiology; D011008:Pneumococcal Infections / Q000175:diagnosis* / Q000209:etiology; D018410:Pneumonia, Bacterial / Q000175:diagnosis* / Q000209:etiology; D011024:Pneumonia, Viral / Q000175:diagnosis* / Q000209:etiology; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies
chemical_list: D002097:C-Reactive Protein