Fixed cut-off for FEV1FEV6 and FEV6 in detection of obstructive and restrictive patterns

الملخص EN

Background : Chronic obstructive pulmonary diseases (COPD) have been defined by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) as irreversible conditions which are diagnosed by fixed cut-off points of FEV1 / FVC.

Objective : The aim of this study was to determine the cut-off points for FEV1 / FEV6 ratio and FEV6 as alternatives for FEV1 / FVC and FVC in detection of airway obstruction and lung restriction, respectively.

Materials and Methods : A total of 318 Spiro metric examinations of subjects referred to Shariati hospital were analyzed.

A subject was considered to have obstruction if FEV1 / FVC was lower than 70 %.

The restriction was defined as FVC & lt ; 80 % in the absence of obstruction.

The Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of FEV1 / FEV6 and FEV6 were calculated.

Results : This study shows that the current cut-off points used to detect obstruction and restriction can be replaced by FEV1 / FEV6 & lt ; 71 % and FEV6 & lt ; 83 %, respectively.

FEV1 / FEV6 had sensitivity of 95.5 % and specificity of 99.4 % ; the PPV and NPVs were 99.3% and 96.3 %.

The prevalence of obstruction was 49.4 %.

For restrictive pattern, FEV6 had sensitivity of 93 %, specificity of 79.5 % with PPV of 18 % and NPV of 99.5 %.

The prevalence of restriction was 6.3 %.

Conclusions : The FEV1/FEV6 ratio can be used as a valid surrogate for FEV1 / FVC in the diagnosis of airway obstruction, especially for screening purposes in high-risk populations for COPD.

Moreover, FEV6 is an acceptable alternative for FVC in detection of restrictive pattern.