Chronic obstructive pulmonary disease (COPD) is a common respiratory disease in China, and it is estimated that there are more than 40 million patients with COPD nationwide. Chronic obstructive pulmonary disease causes a decline in lung function, which, if not actively treated, will repeatedly worsen and affect physical activity, and further development will lead to respiratory insufficiency (respiratory failure) and pulmonary heart disease. Since chronic obstructive pulmonary disease is a common disease, doctors are very familiar with it and mostly believe that a diagnosis can be made based on the medical history (chronic cough, coughing, dyspnea), combined with the results of pulmonary function tests. However, in clinical practice, we have seen cases where the diagnosis of LBP was made “incorrectly”. Mr. Wang, who is not yet 50 years old, often coughs and wheezes when he was young, and his condition has worsened in the past three years. After several visits to other hospitals, he had a pulmonary function test, which showed “severe obstructive ventilatory dysfunction” and “negative reversibility test”, so he was diagnosed with chronic obstructive pulmonary disease and given various inhalation medications. After treatment, his dyspnea only improved slightly and his physical activity was still greatly affected, so he came to my clinic. As soon as I saw Mr. Wang’s appearance, I knew that he was a person who had been suffering from wheezing for a long time: he looked thin, walked slowly, seemed to be struggling to breathe, and had a cough from time to time. When I learned that he had coughing and wheezing since he was young, and that he had never smoked, I suspected that this was probably so-called “refractory asthma” and not necessarily “chronic obstructive pulmonary disease”. The lung function test was repeated and the result was similar to the original one, “severe obstructive ventilation dysfunction, negative reversibility test”. Considering that his symptoms had not improved significantly, it was likely that inhaled medications (including inhaled hormones and bronchodilators) had difficulty achieving satisfactory results. Therefore, I gave him “oral hormone” treatment in order to see if there was any significant improvement in his symptoms and whether his lung function could be further improved through this “intensive” treatment. At the same time, I also suggested him to have a high-resolution CT examination of his lungs to see if there was any emphysema, because chronic obstructive pulmonary disease can have emphysema, but asthma usually does not cause emphysema. Just one week later, Mr. Wang came back to my office and looked like a different person, his “wheezing” was completely gone. He said that in such a long time, he had never been able to breathe as smoothly as he was now, and he could walk faster and go up the stairs… Of course, his lung function test results were also significantly better. The lung CT examination also did not reveal emphysema. The improvement of symptoms and lung function after oral hormone treatment, combined with the CT examination results, can confirm that this is bronchial asthma and not slow-onset lung. Most of bronchial asthma can achieve satisfactory results with inhaled hormone therapy, and lung function remains normal. However, there are a few patients with asthma, especially long-term asthma, who have so-called “irreversible” airflow limitation, and the effect of inhaled hormones is not optimal, and some of them will be “wrongly” labeled as having slow-onset lung. In such cases, international and national guidelines recommend the use of the “oral hormone reversibility test”, which is generally used for 2 weeks to rule out chronic obstructive pulmonary disease when symptoms and lung function improve significantly.