Introduction: The reduction in the ratio between forced expiratory volume in 1s (FEV1) and forced vital capacity (FVC) is used for the diagnosis of chronic obstructive pulmonary disease (COPD). The choice between a simple fixed cut-off ratio (FEV1/FVC LLN had well-preserved FEV1. Conclusion: Using the fixed ratio for diagnosing COPD in an epidemiological setting results in a higher prevalence than if the LLN is used. Time seems ripe for studying if the same is seen when diagnosing COPD in the clinical setting. © 2012 John Wiley & Sons Ltd.
- Lower limit of normal