What is the most appropriate test to confirm a suspected diagnosis of asthma?

Spirometry is the most appropriate test to confirm a suspected diagnosis of asthma because it objectively measures lung function and helps evaluate how well the airways are functioning. In asthma, the hallmark is the variability in airway obstruction, and spirometry assesses this by measuring the forced expiratory volume in one second (FEV1) and the forced vital capacity (FVC).

When a patient with suspected asthma performs spirometry, a significant reduction in FEV1 along with an improvement in airflow after administration of a bronchodilator indicates the presence of asthma. This test not only assists in diagnosing asthma but also helps in monitoring the disease and evaluating treatment efficacy over time.

While other tests may have their roles in assessing respiratory conditions, spirometry is specifically targeted towards diagnosing asthma and providing crucial information about the presence and severity of airway obstruction.