Older people without lung disease may be misdiagnosed with COPD due to normal age-related decline in lung function, Queensland researchers say.
Bond University’s Institute for Evidence-Based Healthcare academics have proposed that age-specific ranges for FEV1, FVC and FEV1 /FVC may be more appropriate than the fixed thresholds currently used for diagnosing COPD.
But their calls to redefine chronic airway disease in older age have been rejected by leading respiratory physician Professor Peter Frith.
Their systematic review covering 16 cohort studies (31,099 participants) included measures of lung function at multiple time points in an ageing population including beyond 65 years of age. It found all studies demonstrated a decline in lung function over age, with a median rate of decline of FEV1 of 22.4 mL/year for studies with a follow-up of at least 10 years.
Rates of decline in lung function increased either from the fourth to the eighth or from the seventh through to the tenth decade.
The study authors said that spirometers used in practice commonly derive their reference values from the cross-sectional National Health and Nutrition Examination Survey (NHANES).
“Though the predicted values do reflect a decline in FEV1 and FEV1 /FVC with age, these decline rates may not be as reliable as the estimates from longitudinal studies included in our review.”
“Therefore, the predicted age-specific lung function used in spirometers may often mislabel people as having abnormal lung function when they are actually within normal limits.”
“If a patient is symptomatic and has airflow obstruction as defined by GOLD criteria, it may be necessary to consider alternative diagnoses such as a dyspnoea of cardiac origin,” they added.