Photo Credit: Svitlana Hulko

The following is a summary of “Effect of a post-bronchodilator FEV₁/FVC < 0.7 on COPD diagnosis and treatment: a regression discontinuity design,” published in the April 2025 issue of Respiratory Research by Moffett et al.

The Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines define chronic obstructive pulmonary disease (COPD) based on a post-bronchodilator ratio of forced expiratory volume in one second to forced vital capacity (FEV₁/FVC) less than 0.7. While this fixed threshold is central to clinical diagnosis criteria, its real-world influence on provider behavior regarding diagnosis and treatment remains unclear. To investigate this, researchers conducted a regression discontinuity analysis using data from a large, national electronic health record database, encompassing patient encounters from 2007 to 2022. The study group focused on individuals aged 18 years or older who had at least one clinical encounter with a recorded post-bronchodilator FEV₁/FVC measurement. 

The primary objective was to evaluate whether crossing the 0.7 diagnostic cutoff influenced subsequent COPD diagnosis or the initiation of treatment. A diagnosis was identified based on the presence of an ICD code for COPD, while treatment was defined as the filling of a prescription for any medication typically used to manage COPD within 90 days of the encounter. The cohort included 27,817 clinical encounters involving 18,991 unique patients, of which 14,876 (53.4%) had a documented FEV₁/FVC ratio below 0.7. The analysis revealed that having a FEV₁/FVC ratio just below the 0.7 threshold resulted in a modest 6.0% absolute increase in the likelihood of receiving a COPD diagnosis (from 38.0% above the cutoff to 44.0% below; 95% CI: 1.1% to 10.9%). However, the same threshold had no statistically significant impact on treatment initiation, with a change of –2.1% (95% CI: –7.2% to 3.0%). 

These findings suggest that, although the fixed FEV₁/FVC ratio recommended by GOLD plays a measurable role in shaping diagnostic patterns, it exerts minimal influence on treatment decisions in practice. This gap between diagnosis and treatment raises important questions about the integration of spirometric data into clinical decision-making and the degree to which other factors—such as symptom burden, comorbidities, or physician interpretation—drive therapy choices. Furthermore, the modest diagnostic impact implies that many clinicians may exercise discretion beyond the rigid spirometric cutoff, highlighting potential variability in how guidelines are applied. Ultimately, the results underscore a need to re-evaluate how guideline-recommended thresholds influence real-world behavior and to consider strategies that better align diagnostic criteria with clinical management practices to ensure patients with COPD receive timely and appropriate care.

Source: respiratory-research.biomedcentral.com/articles/10.1186/s12931-025-03198-6