Primary care respiratory journal : journal of the General Practice Airways Group
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Observational Study
Impact of switching to new spirometric reference equations on severity staging of airflow obstruction in COPD: a crosssectional observational study in primary care.
Severity of airflow obstruction in chronic obstructive pulmonary disease (COPD) is based on forced expiratory volume in one second expressed as percentage predicted (FEV1%predicted) derived from reference equations for spirometry results. ⋯ Compared with the (corrected) ECSC equations, switching to more contemporary reference equations would result in lower FEV1 predicted values and affect interpretation of spirometry by reclassifying 6-14% of primary care COPD patients into different (mostly milder) severity stages. If and how this will affect GPs' treatment choices in individual patients with COPD requires further investigation.