title: Diagnostic Utility of Biomarkers in COPD.
abstract: BACKGROUND
  COPD will become the third leading cause of death by 2020. There are many situations in which spirometry, the primary tool for diagnosis of COPD, cannot be performed, and thus, the staging and status of these patients cannot be determined. To date, there is no known biochemical marker used for diagnosing COPD. This study aimed to explore the utility of biomarkers for diagnosis of COPD.
  
  
  METHODS
  This was an observational study composed of 96 stable subjects with COPD and 96 subjects with normal lung function. Each group contained an equal number of smokers and nonsmokers. Serum levels of superoxide dismutase 3, glutathione peroxidase, catalase, ceruloplasmin ferroxidase activity, C-reactive protein, and surfactant protein D (SPD) were estimated. Ferroxidase activity was estimated by a kinetic method, whereas the other analytes were measured by enzyme-linked immunosorbent assay. The cutoff value, sensitivity and specificity at the cutoff value, and area under the curve for each analyte were determined from receiver operating characteristic curve.
  
  
  RESULTS
  Significantly decreased superoxide dismutase 3 and increased ferroxidase activity, SPD, glutathione peroxidase, and C-reactive protein levels were found in subjects with COPD. For all subjects and nonsmoking subjects with COPD, the area under the curve was highest for ferroxidase activity, followed by glutathione peroxidase, SPD, and C-reactive protein, with a sensitivity and specificity of > 73%. For smoking subjects with COPD, the area under the curve was highest for SPD, followed by glutathione peroxidase, ferroxidase activity, and C-reactive protein, with a sensitivity and specificity > 67%. Some combinations of markers were found to give either a sensitivity or specificity of > 95%, which can be utilized to rule in and rule out COPD.
  
  
  CONCLUSIONS
  Biomarkers can be reliably utilized in the diagnosis of COPD. Of all the markers, SPD appears to be the most promising in smokers, whereas ferroxidase activity shows promise in nonsmokers. To rule out COPD, ferroxidase activity or glutathione peroxidase can be potentially useful, whereas to rule in COPD, ferroxidase activity and glutathione peroxidase appear to be the most promising combination in both nonsmoking and smoking subjects.
authors.affiliation: Department of Biochemistry vivekambade@rediffmail.com.
authors.forename: Vivek N
authors.initials: VN
authors.lastname: Ambade
authors.affiliation: Department of Biochemistry, Maharashtra Institute of Medical Education and Research Medical College, Talegaon, Pune, India.
authors.forename: Alka N
authors.initials: AN
authors.lastname: Sontakke
authors.affiliation: Department of Respiratory Medicine, Cardio-Thoracic Centre, Pune, India.
authors.forename: M S
authors.initials: MS
authors.lastname: Barthwal
authors.affiliation: Department of Respiratory Medicine, Cardio-Thoracic Centre, Pune, India.
authors.forename: R
authors.initials: R
authors.lastname: Tyagi
authors.affiliation: Department of Community Medicine, Armed Forces Medical College, Pune, India.
authors.forename: Dashrath R
authors.initials: DR
authors.lastname: Basannar
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D015415:Biomarkers / Q000097:blood*; D002097:C-Reactive Protein / Q000032:analysis; D016022:Case-Control Studies; D002374:Catalase / Q000097:blood; D002570:Ceruloplasmin / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005979:Glutathione Peroxidase / Q000097:blood; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood*; D037663:Pulmonary Surfactant-Associated Protein D / Q000097:blood; D012372:ROC Curve; D012016:Reference Values; D012907:Smoking / Q000097:blood; D013482:Superoxide Dismutase / Q000097:blood
chemical_list: D015415:Biomarkers; D037663:Pulmonary Surfactant-Associated Protein D; D002097:C-Reactive Protein; D002374:Catalase; D005979:Glutathione Peroxidase; C441642:SOD3 protein, human; D013482:Superoxide Dismutase; D002570:Ceruloplasmin
keywords: C-reactive protein; antioxidants; biomarker; catalase; ceruloplasmin ferroxidase; chronic obstructive pulmonary disease; glutathione peroxidase; superoxide dismutase 3; surfactant protein D