The most appropriate management is to repeat spirometry. Lung function can worsen over time in patients with COPD. During each visit, new or worsening symptoms (cough, sputum, dyspnea, fatigue), smoking status, adherence to and effectiveness of the medication regimen, adverse effects of treatment, and inhaler technique should be assessed. The frequency, severity, and causes of exacerbations should be evaluated. Comorbidities should be identified and managed. Spirometry is indicated when patients with COPD experience a change in symptoms. Annual spirometry can help determine which patients have rapid decline in lung function. Because this patient had pulmonary function testing done 3 years ago and has since had a decrease in his exercise capacity, spirometry is indicated. If spirometry shows worsening airflow obstruction in this patient, addition of a long-acting β₂-agonist and an inhaled glucocorticoid may help with symptom control. If spirometry does not show significant worsening of airflow, other comorbidities such as cardiovascular disease should be considered.

Roflumilast is a phosphodiesterase-4 inhibitor that is indicated in patients with severe and very severe COPD with recurrent exacerbations. This patient does not meet these criteria for use of this medication.

Monitoring patients with COPD using complete pulmonary function testing (with lung volumes and diffusing capacity) rather than spirometry is not cost effective and does not change management. Complete pulmonary function testing is not required unless lung volume reduction surgery (LVRS) or lung transplantation is being considered.

CT of the chest is not routinely recommended in the monitoring of COPD. This patient had a recent chest radiograph, which was normal, and there are no symptoms or signs to suggest a tumor that would warrant a CT scan at this time. Chest CT would be useful if this patient was being evaluated for LVRS or lung transplantation.

Oxygen therapy is not indicated because an oxygen saturation greater than 88% is adequate. If oxygen saturation is less than 92%, arterial blood gas studies should be performed.