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COMPARISON OF TWO METHODS IN THE DIAGNOSIS OF AIRWAY OBSTRUCTION. İlknur Başyiğit , Serap Barış , Haşim Boyacı, Füsun Yıldız Kocaeli University Faculty of Medicine Chest Disease Department. INTRODUCTION.
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COMPARISON OF TWO METHODS IN THE DIAGNOSIS OF AIRWAY OBSTRUCTION İlknur Başyiğit, Serap Barış, Haşim Boyacı, Füsun Yıldız Kocaeli UniversityFaculty of MedicineChestDiseaseDepartment
INTRODUCTION • Pulmonary function test has been used for the diagnosis and follow up the treatment of airway diseases. • Different definitions of airway obstruction cause major changes of prevalence estimates. -Viegi G, Pedreschi M, Pistelli F et al. Prevalence of airway obstruction in a general population. European Respiratory Society vs American Thoracic Society definition. Chest 2000; 117:Suppl.2, 339S-345S. -Shirtcliffe P, Weatherall M, Marsh S, Travers J, Hansell A, McNaughton A, Aldington S, Muellerova H, Beasley R. COPD prevalence in a random population survey: a matter of definition. Eur Respir J 2007; 30:232-239.
INTRODUCTION • It is suggested that the fixed ratio for FEV1/FVC which is recommended in 2001 GOLD report for practical reasons and it is also accepted by ATS/ERS, would overestimate the prevalence of COPD in older population since FEV1/FVC will decrease with age and underestimate the frequency of obstructive disorders in younger population. -Hardie JA, Buist AS, Vollmer WM, Ellingsen I, Bakke PS, Murkve O. Risk of overdiagnosis of COPD in asymptomatic elderly never-smokers. Eur Respir J 2002;20: 1117-1122. -Hnizdo E, Glindmeyer HW, Petsonk EL, Enrigt P, Buist AS. Case definitions for chronic obstructive pulmonary disease. COPD 2006;3: 95-100. -Roberts SD,Farber MO, Knox KS, Phillips GS, Bhatt NY, Mastronarde JG, et al. FEV1/FVC ratio of %70 misclasifies patients with obstruction at the extremes of age. Chest 2006; 130:200-236.
INTRODUCTION • In 2005; ATS/ERS suggested to use Lower Limit of Normal (LLN; level lower than 5% predicted) for definition of airway obstruction instead of fixed ratio and this suggestion was supported by several recent studies. -Roberts SD, Farber MO, Knox KS et al. FEV1/FVC ratio of 70% misclassifies patients with obstruction at extremes of age. Chest 2006;130: 200-206. -Hansen JE, Sun XG, Wasserman K. Spirometric criteria for airway obstruction. Use percentage of FEV1/FVC ratio below the fifth percantile, Not <70%. Chest 2007;131:349-355.
INTRODUCTION • Use of fixed ratio for definition of airway obstruction was recommended again in 2006 GOLD report, until longitudinal studies investigating validity of LLN performed.
AIM • The aim of this study was to compare the LLN and fixed ratio for the FEV1/FVC level in the diagnosis of airway obstruction.
MATERIAL AND METHOD • A questionnaire for respiratory symptoms was applied and physical examination was performed in the teachers. • Pulmonary function test (PFT) was done by a technician using portable spirometer in cases that accept to join the study and can perform the spirometry maneuver. • PFT was performed using Koko Legend portable spirometer.
MATERIAL AND METHOD • Mean age, gender, respiratory symptoms and physical examination of participants were recorded. • FEV1, FVC, FEV1/FVC values were determined. • LLN for the FEV1/FVC ratio was determined as the 5% lower of the predicted FEV1/FVC levels and calculated for each case.
RESULTS • Totally 616 cases included in the study, 55% of the cases were male (n: 338), 45% of them were female (n: 278) and mean age was 38.9 ± 8.8 years. • Mean FEV1 level was 3.3 ± 0.7 l and mean FVC level was 4.1 ± 0.9 l.
RESULTS • FEV1/FVC was lower than 70% in 4 cases while the ratio was found to be LLN in 12 of the cases. • All of 4 cases who determined as obstructive by fixed FEV1/FVC ratio were also defined as obstructive according to LLN.
TABLE-2:THE NUMBER OF OBSTRUCTIVE AND NON-OBSTRUCTIVE CASES ACCORDING TO LLN AND FEV1/FVC
TABLE-3:DISTRUBITION OF OBSTRUCTIVE AND NON-OBSTRUCTIVE CASES ACCORDING TO AGE
RESULTS • Five of the 8 cases who determined as obstructive by using the LLN for the FEV1/FVC ratio, had complain of dyspnea, • Three of the 8 cases reported the episodes of dyspnea and wheezing • Two of them had doctor-diagnosed asthma. • Prolongation of expiration and diffuse expiratory rhonchi was found in the physical examination of the 4 cases.
CONCLUSION • It is suggested that using LLN for FEV1/FVC ratio might be more accurate than fixed cut-off in the diagnosis of airway obstruction especially in the younger population.