title: Pulmonary function tests, sputum induction, and bronchial provocation tests: diagnostic tools in the challenge of distinguishing asthma and COPD phenotypes in clinical practice.
abstract: BACKGROUND
  despite a number of important differences in the pathogenesis, course, and prognosis, asthma and chronic obstructive pulmonary disease (COPD) have many features in common. Furthermore, smoking induces considerable overlap in pathogenesis and clinical features between these conditions. This study aimed to reveal what inflammatory patterns prevail in clinically established diagnosis groups, including overlap phenotypes of asthma and COPD, and to evaluate the correlation with airway reversibility and hyperreactivity in these overlapping conditions.
  
  
  METHODS
  a total of 110 patients (17 healthy subjects; 16 "healthy" smokers; 46 asthma patients: 24 smokers and 22 non-smokers; and 31 COPD patients: 10 COPD patients with reversibility and 21 without) participated in the study. Induced sputum, reversibility testing, methacholine and adenosine 5'monophosphate (AMP) provocation challenges, and skin prick testing were performed. Airways inflammation was assessed by differential cell counts, and cytokines (interleukin-8 [IL-8] and tumor necrosis factor-alpha [TNF-α]) were measured in induced sputum by enzyme-linked immunosorbent assay (ELISA).
  
  
  RESULTS
  COPD patients with reversibility had increased sputum neutrophils, IL-8, and TNF-α levels compared to smoking asthmatics. No difference was found in inflammatory cells and cytokines between COPD subgroups. Sputum neutrophilia was inversely correlated with the change in forced expiratory volume in one second (ΔFEV(1)) in smoking asthmatic patients (r = -0.563, P = 0.036). No correlation was found between airway hyperresponsiveness (AHR), either with methacholine or AMP, and inflammation in asthmatic patients, regardless of smoking. Reversibility was not correlated with inflammation in COPD patients. However, the response to AMP challenge was correlated with sputum neutrophils (r = 0.844, P = 0.001).
  
  
  CONCLUSIONS
  although overlaps exist in the disease characteristics of asthma and COPD, the combination of lung function testing, sputum induction, and AHR reveals information that facilitates the distinction between these diseases, allowing clinicians to better tailor their therapy.
authors.affiliation: Sotiria Hospital for Diseases of the Chest, Department of Respiratory Medicine, University of Athens, Medical School, Athens, Greece.
authors.forename: Efrossini
authors.initials: E
authors.lastname: Dima
authors.forename: Nikoletta
authors.initials: N
authors.lastname: Rovina
authors.forename: Christina
authors.initials: C
authors.lastname: Gerassimou
authors.forename: Charis
authors.initials: C
authors.lastname: Roussos
authors.forename: Christina
authors.initials: C
authors.lastname: Gratziou
mesh_terms: D000328:Adult; D001249:Asthma / Q000175:diagnosis*; D016535:Bronchial Hyperreactivity / Q000503:physiopathology*; D016207:Cytokines / Q000032:analysis; D003937:Diagnosis, Differential; D003955:Diagnostic Tests, Routine; D006801:Humans; D016209:Interleukin-8 / Q000032:analysis; D008875:Middle Aged; D010641:Phenotype; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000235:genetics; D012129:Respiratory Function Tests; D012907:Smoking; D013147:Spirometry / Q000379:methods; D013183:Sputum / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
chemical_list: D016207:Cytokines; D016209:Interleukin-8; D014409:Tumor Necrosis Factor-alpha