What is the best initial diagnostic test for suspected COPD?

Spirometry is the best initial diagnostic test for suspected chronic obstructive pulmonary disease (COPD) because it measures the amount and speed of air that can be inhaled and exhaled. This test is essential for assessing airflow obstruction, which is a key feature of COPD. In particular, it evaluates forced expiratory volume in one second (FEV1) and forced vital capacity (FVC), and the ratio of these values can help determine the presence and severity of the disease.

While other tests like chest X-ray or CT scans can provide useful information about the lungs and help rule out other conditions, they do not assess airflow rates directly. Similarly, pulmonary function tests encompass a broader array of assessments, but spirometry specifically is the standard and most effective first step in diagnosing COPD due to its direct focus on measuring airway obstruction. Consequently, spirometry is aligned with guidelines for the diagnosis and management of COPD.