Kurashima K, et al. - This investigation was pursued to clarify if or not a smoking history (≥10 pack-years) and emphysema are useful markers for classifying asthma–COPD overlap (ACO) and distinguishing it from asthma with chronic airflow obstruction (CAO). Researchers found that smoking history (≥10 pack-years) was a useful marker for differentiating ACO and asthma with CAO, and emphysema was a useful marker for classifying ACO. Notably, as predictors of the overall survival and frequency of exacerbation, these markers displayed usefulness.