Diagnostic Value of Fixed Ratio Criteria for Airway Obstruction Assessment

· Lung Function

Rudi Dermawan, Faisal Yunus, Budhi Antariksa


Background : The Diagnostic value of spirometry test based on fixed ratio 0.75 to assess airway obstruction had not known yet in Indonesia. The purpose of this study was to know the diagnostic value of fixed ratio FEV1/FVC base on Pneumobile Indonesia as lower limit of normal (LLN) for diagnosis of airway obstruction disease. Methods: Cross sectional study of 428 adult subjects performed spirometry at Pasar Sunan Giri and spirometry laboratory in Persahabatan Hospital according to American Thoracic Society (ATS) 1987 recommendations. The spirometry results that met the acceptable and reproducible criteria analyzed by LLN and fixed ratio criteria to know normal or obstructive pattern. Results : A total 400 subjects met acceptable and reproducible criteria of spirometry result, consist of 273 male (68.2%) and 127 female (31.8%) with age between 16-70 years old, (median : 31-40 y.o) including 239 (59.8%) smoker. The median height was 162 (150-172) cm. Overall, we found 21 (5.3%) subjects had obstructive pattern. The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of the test respectively were 68%, 98%, 71%, 98% and 98%. The ROC give 0.97 for AUC (95%CI 0.95-1). The better fixed ratio (sensitivity and specificity) found for under 40 y.o and more than 40 y.o were 0.81 (86%, 93%) and 0.77 (100%, 95%). Conclusion : Fixed ratio of 0.75 FEV1/FVC has low sensitivity and high specificity to assess airway obstructive disease. The better fixed ratio (sensitivity and specificity) for under 40 y.o and more than 40 y.o are 0.81 (86%, 93%) and 0.77 (100%, 95%). (J Respir Indo. 2013; 33:210-20)

Keywords : Spirometry, lower limit of normal, fixed ratio, airway obstruction.

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