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

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.

Efficacy of the FEV1/FEV6 ratio compared to the FEV1/FVC ratio for the diagnosis of airway obstruction in subjects aged 40 years or over

The present cross-sectional, population-based study was designed to evaluate the performance of the FEV1/FEV6 ratio for the detection of airway-obstructed subjects compared to the FEV1/FVC <0.70 fixed ratio test, as well as the lower limit of normality (LLN) for 1000 subjects ³40 years of age in the metropolitan area of São Paulo, SP, Brazil. After the exclusion of 37 (3.7 percent) spirometries, a total of 963 pre-bronchodilator (BD) and 918 post-BD curves were constructed. The majority of the post-BD curves (93.1 percent) were of very good quality and achieved grade A (762 curves) or B (93 curves). The FEV1/FEV6 and FEV1/FVC ratios were highly correlated (r² = 0.92, P < 0.000). Two receiver operator characteristic curves were constructed in order to express the imbalance between the sensitivity and specificity of the FEV1/FEV6 ratio compared to two FEV1/FVC cut-off points for airway obstruction: equal to 70 (area under the curve = 0.98, P < 0.0001) and the LLN (area under the curve = 0.97, P < 0.0001), in the post-BD curves. According to an FEV1/FVC <0.70, the cut-off point for the FEV1/FEV6 ratio with the highest sum for sensitivity and specificity was 0.75. The FEV1/FEV6 ratio can be considered to be a good alternative to the FEV1/FVC ratio for the diagnosis of airway obstruction, both using a fixed cut-off point or below the LLN as reference. The FEV1/FEV6 ratio has the additional advantage of being an easier maneuver for the subjects and for the lung function technicians, providing a higher reproducibility than traditional spirometry maneuvers.

FEV_6 as a surrogate for FVC in the diagnostic screening for chronic obstructive pulmonary disease / 中国实用内科杂志

Objective The purpose of this study was to determine the efficacy of forced expiratory volume in six seconds(FEV6) as an alternative for forced vital capacity(FVC)and the fixed eat-off points for FEV1/FEV6 in the diagnostic screening for chronic obstructive pulmonary disease (COPD).Methods From August 2007 to December 2008,a total of 1210 spirometric examinations in were analyzed,FEV6 was measured on volume-time curves.The correlation between FEV1/FVC and FEV1/FEV6 was evaluated by the Kendall correlation test.Considering FEV1/FVC