title: Capsaicin cough threshold test in diagnostics.
abstract: BACKGROUND
  Among patients with chronic unexplained cough, there is a recognized subgroup with respiratory symptoms induced by environmental irritants like chemicals and odours. The diagnosis of sensory hyperreactivity (SHR) has been suggested for this group of patients and can be made using a tidal breathing capsaicin inhalation test. The aim of the present study was to evaluate the ability of a single-breath, dose-response capsaicin threshold test to discriminate such patients from control subjects.
  
  
  METHODS
  A total of 46 patients with chronic cough and SHR who had previously shown a positive reaction in accordance with limits set for a tidal breathing capsaicin test were tested once with a single-breath, dose-response capsaicin cough threshold test, assessing capsaicin concentrations to evoke 2 (C2), 5 (C5) or 10 (C10) coughs. Twenty-nine subjectively healthy control subjects were also included and tested with the threshold method.
  
  
  RESULTS
  Patients had significantly lower C2, C5 and C10 in comparison to controls. From the results among patients and controls, sensitivity and specificity were calculated, and a receiver operating characteristic curve was constructed, showing excellent ability for C5 and C10 to discriminate patients from control subjects.
  
  
  CONCLUSIONS
  For patients with SHR and chronic cough, capsaicin cough sensitivity was once again confirmed to be increased, in this case, using the single-breath dose-response method. Limits set for cough reactions regarded as more sensitive than normal can be useful in diagnostics and further research. C5 seems to be the best measure to use in research and differential diagnostics.
authors.affiliation: Department of Respiratory Medicine and Allergology, The Sahlgrenska Academy, University of Gothenburg, Sweden. Electronic address: teet.pullerits@vgregion.se.
authors.forename: Teet
authors.initials: T
authors.lastname: Pullerits
authors.affiliation: Department of Respiratory Medicine and Allergology, The Sahlgrenska Academy, University of Gothenburg, Sweden. Electronic address: ewa.ternesten@lugall.gu.se.
authors.forename: Ewa
authors.initials: E
authors.lastname: Ternesten-Hasséus
authors.affiliation: Department of Clinical Neuroscience and Rehabilitation, The Sahlgrenska Academy, University of Gothenburg, Sweden; Department of Physiotherapy, The Sahlgrenska Academy, University of Gothenburg, Sweden. Electronic address: ewa-lena.johansson@vgregion.se.
authors.forename: Ewa-Lena
authors.initials: EL
authors.lastname: Johansson
authors.affiliation: Department of Respiratory Medicine and Allergology, The Sahlgrenska Academy, University of Gothenburg, Sweden. Electronic address: eva.millqvist@medfak.gu.se.
authors.forename: Eva
authors.initials: E
authors.lastname: Millqvist
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D000368:Aged; D001944:Breath Tests / Q000379:methods; D001985:Bronchial Provocation Tests / Q000379:methods; D002211:Capsaicin / Q000008:administration & dosage; D016022:Case-Control Studies; D002908:Chronic Disease; D003371:Cough / Q000139:chemically induced*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018777:Multiple Chemical Sensitivity / Q000150:complications / Q000175:diagnosis*; D012372:ROC Curve; D018689:Sensory System Agents / Q000008:administration & dosage; D012684:Sensory Thresholds; D055815:Young Adult
chemical_list: D018689:Sensory System Agents; D002211:Capsaicin
keywords: Capsaicin; Chronic cough; Cough hypersensitivity syndrome; Sensory hyperreactivity; Single-breath method; Threshold test