The Journal of asthma : official journal of the Association for the Care of Asthma
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Subjects with bronchial asthmatic symptoms, forced expiratory volume in 1 second (FEV(1)) and FEV(1)/forced vital capacity [FVC] > 80% could show a positive reversibility test with salbutamol in about 25% of the cases. The aim of this study was to evaluate if a limit functional value for spirometry exists where a reversibility test using salbutamol, over this limit, is not necessary to confirm the diagnosis of asthma. Four hundred patients (mean age 31.12 +/- 10.99) with asthmatic symptoms and normal spirometry (mean FEV(1) 96.06 +/- 11.82%, mean FEV(1)/FVC 98.89 +/- 6.03%) were recruited. ⋯ FEV(1) > 121% or FEV(1)/FVC > 110.8% or FEF(25 -75) > 110% were cut-off values identified in this study where no RAO subjects were found over these limits. In conclusion, baseline FEV(1) > 100%, FEV(1)/FVC > 100% and FEF(25 -75) > 70% cannot be considered cut-offs where it is not necessary to perform a reversibility test with a bronchodilator over these limits. It is improbable to find a positive reversibility test using salbutamol in patients with asthmatic symptoms and FEV(1) > 121% or FEV(1)/FVC > 110.8% or FEF(25 -75) > 110% to confirm the diagnosis of asthma.