In aging populations, accurately diagnosing chronic obstructive pulmonary disease (COPD) presents a challenge due to the limitations of existing diagnostic criteria, according to a study published online in Lung. This study compared two spirometry thresholds—Global Initiative for Obstructive Lung Disease (GOLD) and Global Lung Initiative (GLI)—to evaluate their impact on classifying older patients who smoke into COPD risk phenotypes. The findings suggested that reliance on the fixed GOLD threshold may misclassify patients with normal or mildly affected lung function as having more severe respiratory impairment, potentially leading to overtreatment and unnecessary interventions.
“To further explore this issue, we used our clinical algorithm to investigate how the GOLD and GLI thresholds might affect the classification into COPD risk phenotypes of patients who smoke aged 60 years and older,” study authors noted. “This investigation was particularly relevant given the higher prevalence of COPD in older age groups and the potential risks associated with overdiagnosis, such as unnecessary medication use and increased likelihood of adverse effects.
Traditionally, GOLD defines airflow obstruction as a fixed FEV1/FVC ratio <0.7. However, lung function naturally declines with age, making this fixed threshold prone to misclassification, particularly in older adults. To address this limitation, the GLI employs age-adjusted z-scores, which account for age-related changes in spirometry. This study applied a modified COPDGene algorithm to 200 patients who smoke aged 60 years and older, categorizing them into four phenotypes: A (no symptoms, normal spirometry), B (symptoms, normal spirometry; possible COPD), C (no symptoms, abnormal spirometry; possible COPD), and D (symptoms, abnormal spirometry; probable COPD).
Results revealed that using GLI thresholds increased the proportion of patients classified as phenotype A (18.5% vs. 14.5%) while decreasing those classified as the most severe phenotype D (32% vs. 43%) compared to GOLD thresholds. Notably, 15% of participants were reclassified into less severe phenotypes under GLI, including eight patients with GOLD-defined phenotype C (possible COPD) who were reclassified as phenotype A (normal), and 22 patients with GOLD-defined phenotype D who shifted to phenotype B (possible COPD). Those identified as probable COPD by GOLD alone had better spirometry results than those classified as probable COPD by both thresholds, indicating potential overdiagnosis by GOLD.
According to the authors, overdiagnosis could expose older patients to unnecessary treatments, such as bronchodilators or steroids, which carry risks of adverse effects. Additionally, the authors note that being incorrectly labeled with a severe disease phenotype could have significant psychological and financial consequences. Comparatively, GLI’s age-adjusted criteria offer a more nuanced approach, reducing the risk of misclassification and aligning spirometric findings more closely with clinical presentation and disease severity.
Beyond spirometry thresholds, the findings advocate for a broader definition of COPD risk that includes symptoms, smoking history, and structural changes, rather than relying solely on the FEV1/FVC ratio. For instance, patients who smoke with symptoms but normal spirometry (phenotype B) or those with abnormal spirometry but no symptoms (phenotype C) would benefit from targeted screening and preventive measures, such as smoking cessation and more sensitive diagnostic tests. Current guidelines, which exclude such patients from screening, risk missing an opportunity for early intervention.
This study builds on prior research that highlights the limitations of the fixed GOLD threshold. Evidence from population studies and longitudinal analyses has shown that GLI-defined criteria better predict clinical outcomes such as mortality, exacerbations, and imaging abnormalities. Moreover, the use of the GOLD threshold has been criticized for oversimplifying the diagnosis of COPD, particularly in older adults, where FEV1/FVC ratios as low as 65% may be normal.
Overall, the GLI threshold provides a more accurate classification of COPD risk phenotypes in older patients who smoke, reducing the risk of overdiagnosis and unnecessary treatment. These findings emphasize the need for age-adjusted diagnostic criteria and a comprehensive approach to COPD risk assessment that goes beyond spirometry alone. Further longitudinal studies are warranted to validate these findings and refine diagnostic strategies for COPD in aging populations.
“This has clinical implications, as COPD is a heterogeneous disease and spirometry, along with other parameters, will remain essential for diagnosis,” the authors concluded.
“Misclassification of [older patients who smoke] into severe COPD phenotypes could lead to inappropriate and harmful treatment. While the economic cost of such misclassification is difficult to estimate, the psychological impact on misdiagnosed patients could be significant. In addition, this study supports previous research suggesting that classifying [patients who smoke] into risk phenotypes, rather than based solely on FEV1/FVC < 0.7, may increase the population requiring screening and support preventive measures such as smoking cessation.”
“Further longitudinal studies are needed to validate these findings.”
