CHEST Guidelines-Performance-Characteristics-of-Spirometry-With-Neg

Performance-Characteristics-of-Spirometry-With-Neg

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The study explores the effectiveness of spirometry with bronchodilator response (BDR) and methacholine challenge testing (MCT) in diagnosing asthma, especially when initial BDR results are negative. Conducted by Janannii Selvanathan and colleagues, the research involved 500 Canadian adults with a history of physician-diagnosed asthma. The study aimed to assess how often a negative BDR test correlated with a positive MCT, and evaluated the impact of tapering asthma control medications, as well as the temporal variability of MCT results.<br /><br />Key findings include that 43% of subjects with a negative BDR test still presented a positive MCT result, indicating that a negative BDR has a limited negative predictive value of 57% for excluding asthma. The presence of pre-bronchodilator airflow limitation was found to significantly increase the likelihood of testing positive in an MCT. Additionally, MCT results could shift from negative to positive over time without medication, and treatment tapering influenced outcomes, as evidenced by 19.1% of test subjects experiencing a change in MCT results during medication adjustment. <br /><br />The research suggests repeated testing might be necessary for patients with high clinical suspicion of asthma, as there were cases where pulmonologists diagnosed asthma despite negative MCT results. These findings highlight the importance of a comprehensive approach in asthma diagnosis, acknowledging that MCT and BDR results alone may not always provide a definitive diagnosis. Therefore, clinicians should apply these tests in conjunction with clinical assessment and consider repeating tests under varying conditions to verify results. Ultimately, the study underscores the complexity and intricacy of asthma diagnosis, advocating for personalized patient assessments.

Keywords

spirometry

bronchodilator response

methacholine challenge testing

asthma diagnosis

negative predictive value

pre-bronchodilator airflow limitation

tapering asthma medications

temporal variability

personalized patient assessments

Janannii Selvanathan