Impact of diagnostic criteria on the prevalence of COPD

INTRODUCTION: The reduction in the ratio between forced expiratory volume in 1 s (FEV(1) ) 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 (FEV(1) /FVC LLN had well-preserved FEV(1) . 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.