Comment on: “The prevalence of asthma-COPD overlap (ACO) among COPD patients and the role of prostaglandin D2 (PGD2) in differential diagnosis”

Asthma-COPD overlap (ACO) is a controversial concept without a universally accepted definition. In the study by Aslan and Enli, ACO was defined based on airflow limitation and reversibility; however, this approach may not fully reflect current guideline perspectives. Recent GINA and GOLD reports emphasize a phenotype-based approach rather than defining ACO as a distinct disease entity. Therefore, the observed limited diagnostic value of prostaglandin D2 (PGD2) may be influenced by methodological limitations, particularly patient selection and classification strategy.