title: Diagnostic accuracy of a pocket screening spirometer in diagnosing chronic obstructive pulmonary disease in general practice: a cross sectional validation study using tertiary care as a reference.
abstract: COPD-6™ is a lung function testing device for a rapid pre-spirometry testing to screen-out at-risk individuals not having COPD and indicating those at risk. The aim of this study was to validate COPD-6™ lung function testing (index test) in general practice in discriminating patients with COPD out of the population at risk - smokers/ex-smokers with no previous diagnosis of COPD, using measurements at tertiary care as reference standard.
  
  
  
  Consecutive 227 subjects (115 women, 185 smokers/42 ex-smokers, ≥20 pack-years) with no previous diagnosis of COPD, aged 52.5 (SD 6.8) years from 26 general practitioners (GPs) were recruited, lung function tested with COPD-6™, referred to the tertiary institution for repeated COPD-6™ testing followed by spirometry with a bronchodilator (salbutamol), examination, and pulmonologist consultation for the diagnosis and severity of COPD.
  
  
  
  COPD was diagnosed in 43 subjects (18.9 %), with an AUC of 0.827 (95 % CI 0.769-0.875, P < 0.001) for the diagnosis of COPD when lung function was measured using COPD-6™ in GP's office with a specificity of 100 % (95 % CI, 97.95-100 %) but a very low sensitivity of 32.56 % (95 % CI, 20.49-47.48 %). Significant agreement for forced expiratory volume in 1 s measured at GP's office and at lung function lab was found (mean difference 0.01 L, p = 0.667) but not for other measured parameters (p < 0.001 for all).
  
  
  
  Our study results point out that active case finding in a population at risk for COPD should be instituted (almost 20 % of undiagnosed COPD). Based on our results lung function testing with COPD-6™ can substitute spirometry testing in cases where it is not readily available to the patient/physician taken into account that the traditional FEV1/FEV6 cutoff value of <0.7 is not the only criterion for diagnosis and/or further referral.
  
  
  
  ClinicalTrials.gov Identifier NCT01550679 Registered 28 September 2014, retrospectively registered.
authors.affiliation: Department of Pulmonology, University Hospital Center Osijek, Josipa Huttlera 4, Osijek, Croatia.|Faculty of Medicine, J.J. Strossmayer University of Osijek, Ulica cara Hadrijana 10E, Osijek, Croatia.
authors.forename: Marina
authors.initials: M
authors.lastname: Labor
authors.affiliation: Department of Pulmonology an Immunology, General Hospital Dubrovnik, Dr. Roka Mišetića 2, Dubrovnik, Croatia.|University of Dubrovnik, Branitelja Dubrovnika 29, Dubrovnik, Croatia.
authors.forename: Žarko
authors.initials: Ž
authors.lastname: Vrbica
authors.affiliation: Department of Pulmonology, University Hospital Center Split, Spinčićeva 1, Split, Croatia.
authors.forename: Ivan
authors.initials: I
authors.lastname: Gudelj
authors.affiliation: Department of Pulmonology, University Hospital Center Osijek, Josipa Huttlera 4, Osijek, Croatia.|Faculty of Medicine, J.J. Strossmayer University of Osijek, Ulica cara Hadrijana 10E, Osijek, Croatia.
authors.forename: Slavica
authors.initials: S
authors.lastname: Labor
authors.affiliation: Faculty of Medicine, J.J. Strossmayer University of Osijek, Ulica cara Hadrijana 10E, Osijek, Croatia. plavec@bolnica-srebrnjak.hr.|Research Department, Children's Hospital Srebrnjak, Srebrnjak 100, Zagreb, Croatia. plavec@bolnica-srebrnjak.hr.
authors.forename: Davor
authors.identifier: 0000-0003-2020-8119
authors.initials: D
authors.lastname: Plavec
mesh_terms: D019540:Area Under Curve; D003430:Cross-Sectional Studies; D005260:Female; D005541:Forced Expiratory Volume; D058006:General Practice / Q000295:instrumentation*; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000295:instrumentation*; D008875:Middle Aged; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000503:physiopathology; D012372:ROC Curve; D015203:Reproducibility of Results; D012307:Risk Factors; D012907:Smoking / Q000503:physiopathology; D016540:Smoking Cessation; D013147:Spirometry / Q000295:instrumentation*; D062606:Tertiary Care Centers
keywords: COPD; Diagnosis; General practice; Screening; Sensitivity and specificity