Obstructive and restrictive spirometric patterns: fixed cut-offs for FEV1/FEV6and FEV6

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Abstract
The purpose of this study was to determine fixed cut-off points for forced expiratory volume in one second (FEV1)/FEV6and FEV6as an alternative for FEV1/forced vital capacity (FVC) and FVC in the detection of obstructive and restrictive spirometric patterns, respectively.For the study, a total of 11,676 spirometric examinations, which took place on Caucasian subjects aged between 20–80 yrs, were analysed. Receiver–operator characteristic curves were used to determine the FEV1/FEV6ratio and FEV6value that corresponded to the optimal combination of sensitivity and specificity, compared with the commonly used fixed cut-off term for FEV1/FVC and FVC.The data from the current study indicate that FEV1/ FEV661/FVC 1/FEV6sensitivity and specificity were 94.4 and 93.3%, respectively; the positive and negative predictive values were 92.2 and 95.2%, respectively. For the spirometric detection of a restrictive pattern (prevalence of 14.9%), FEV6sensitivity and specificity were 95.9 and 98.6%, respectively; the positive and negative predictive values were 92.2 and 99.3%, respectively.This study demonstrates that forced expiratory volume in one second/forced expiratory volume in six seconds <73% and forced expiratory volume in six seconds <82% predicted, can be used as valid alternatives to forced expiratory volume in one second/forced vital capacity <70% and forced vital capacity <80% predicted, as fixed cut-off terms for the detection of an obstructive or restrictive spirometric pattern in adults.