title: Laboratory tests for pneumonia in general practice: the diagnostic values depend on the duration of illness.
abstract: The usefulness in the diagnosis of pneumonia of temperature and the laboratory tests: erythrocyte sedimentation rate (ESR), leucocyte count, and C-reactive protein (CRP) was evaluated against a radiographic reference standard in 402 adult patients with respiratory tract infection in general practice. Radiographic pneumonia was diagnosed in 20 patients. CRP and ESR were the most useful tests. CRP greater than 50 mg/l had lower sensitivity and likelihood ratio (LR), 0.50 and 4.8, respectively, compared with previous studies of selected patient populations. Among patients whose duration of illness exceeded six days the corresponding LR was 11.3, due to a higher specificity in this subgroup of patients. ESR and oral temperature were also more useful in this subgroup than in patients with a shorter duration of illness. A highly significant diagnostic contribution of adding ESR and CRP to history and physical examination, particularly when the illness had lasted one week or more, was demonstrated by logistic regression.
authors.affiliation: Institute of Community Medicine, Hospital of Hammerfest, University of Tromsø, Norway.
authors.forename: H
authors.initials: H
authors.lastname: Melbye
authors.forename: B
authors.initials: B
authors.lastname: Straume
authors.forename: J
authors.initials: J
authors.lastname: Brox
mesh_terms: D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000502:physiology; D005194:Family Practice; D006801:Humans; D007962:Leukocytes / Q000502:physiology; D008487:Medical History Taking; D010808:Physical Examination; D011014:Pneumonia / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D011859:Radiography; D013696:Temperature; D013997:Time Factors
chemical_list: D002097:C-Reactive Protein