ABSTRACT
Objective To determine the value of forced expiratory volume in 6 second (FEV6) and forced expiratory volume in 1 second (FEV1)/FEV6 in diagnosis of obstructive and restrictive lung ventilation dysfunction.Methods A total of 470 cases receiving spirometric examinations were analyzed retrospectively.A subject was considered to have obstruction if FEV1/forced vital capacity (FVC) was ＜ 70％.The restriction was defined as FVC ＜ 80％ in the absence of obstruction.The best cut-off of FEV1/FEV6 and FEV6 were determined through receiver-operating characteristics curve,and the sensitivity,specificity,accuracy and Kappa of FEV1/FEV6 and FEV6 were calculated.Results It showed that the current cut-off points used to detect obstruction and restriction could be replaced by FEV1/FEV6 was 71％ and FEV6 was 82％,respectively.FEV1/FEV6 had sensitivity of 97.5％ (154/158),specificity of 98.7％ (308/312),accuracy of 98.3％ (462/470) and Kappa of 0.962 (P=0.000).For restrictive pattern,FEV6 had sensitivity of 96.1％(73/76),specificity of 95.7％ (222/232),accuracy of 95.8％ (295/308) and Kappa of 0.890 (P =0.000).Conclusions FEV6 can be a valid alternative for FVC in the diagnosis of obstructive and restrictive lung ventilation dysfunction.