Investigation of the optimal surrogate for forced vital capacity in the diagnosis for chronic obstructive pulmonary disease / 中国综合临床

ABSTRACT

Objective To evaluate whether the forced expiratory volume in sixth scend(FEV6) was the optimal surrogate for forced vital capacity (FVC) in the diagnosis for chronic obstructive pulmonary disease (COPD).Methods Retrospectively analyzed the spirometric data of 142 COPD patients (7 cases with mild COPD,60 cases with moderate COPD,48 cases with severe COPD,27 cases with extremely severe COPD) admitted to Hebei Chest Hospital from October 2011 to October 2012 who had FEV6 data.FEV6,FEV5,FEV4 and FEV3 were measured on volume-time curves and the diagnostic value was analyzed.Results FEV6,FEV5,FEV4 and FEV3 were highly correlated to FVC (r =0.994,0.939,0.935 and 0.923 respectively,P ＜0.001).Assuming =70％ as the diagnostic standard for obstruction,FEV1/FEV6 had a diagnostic rate of 92.96％ with a false negative rate of 7.04％.FEV1/FEV5,FEV1/FEV4 and FEV1/FEV3 had higher false negative rates (9.86％,13.38％ and 27.46％ respectively) than FEV6.The value of FEV1/FEV6-FEV1/FVC had no statistical significance between the mild-moderate and the severe-extremely severe COPD groups(t =1.376,P =0.171).Conclusion There is a strong correlation between FEV6 and FVC.FEV6 may be the best surrogate for FVC in the diagnosis of chronic obstructive pulmonary disease.Elevating diagnostic critical value can reduce the false negative rate.