A 65-year-old male comes into your office for a check-up. He states that he has been feeling tired and short of breath but does not have any fevers or cough. He has a history of smoking 1 pack of cigarettes per day for the last 40 years. He states that, over the last few years, he has had difficulty walking even one block. He cannot climb a set of stairs and states that he has been hospitalized many times over the past year for pneumonia. He is prescribed inhaled corticosteroids along with ipratropium and albuterol. His chest radiograph is shown in Figure A. Which of the following is most likely to decrease this patient's risk of hospitalizations for disease exacerbation and development of lung cancer?