Impact of the new European respiratory (ERS)/American Thoracic Society (ATS) pulmonary function test interpretation guidelines 2021 on the interpretation of bronchodilator responsiveness in subjects with airway obstruction

Changes in the Functional Classification of Spirometry Using the New Interpretation Standard 2022: A Multicenter Study

INTRODUCTION

Pulmonary function tests are vital for diagnosing lung diseases, assessing treatment responses, and monitoring respiratory health. Recent updates to interpretive standards by the European Respiratory and American Thoracic Societies (ERS/ATS) in 2022 introduced significant changes compared to the 2005 standards. They include incorporating lung volume measurements, non-specific and mixed disorders, introducing z-scores for functional abnormality assessment, reducing severity categories from five to three, and revising criteria for positive bronchodilator responses.

METHODS

We conducted a retrospective, multi-center study across four centers using spirometric data spanning from 2002 to 2022. We categorized spirometry results using both the 2005 and 2022 ATS/ERS standards and calculated predicted values following the GLI 2012 equation (Caucasian subset).

RESULTS

Among 79,039 subjects, we observed that 23% shifted from an obstructive diagnosis under the 2005 standard to a mixed pattern diagnosis under the 2022 standard, necessitating lung volume assessments. In the evaluation of bronchodilator responses among 59,203 tests, 12.3% of those initially classified as responders were reclassified as non-responders with the new standards. We found variations in severity categorization across age groups, with older patients tending to receive milder severity classifications and younger individuals receiving greater severity classifications under the 2022 standards.

CONCLUSIONS

The 2022 document emphasizes early lung volume assessment, potentially leading to increased utilization of more complex tests. Furthermore, the bronchodilator response was predominant in extreme age groups and among individuals with milder spirometric impairments. This shift may impact treatment decisions, potentially initiating medication in milder cases and de-escalating treatment in more severe cases.

Assessment of bronchodilator responsiveness to salbutamol or ipratropium using different criteria in treatment-naïve patients with asthma and COPD

Background

The criteria for significant bronchodilator responsiveness (BDR) were published in 2005 by the European Respiratory Society/American Thoracic Society, which were revised in 2021, however, data on the agreement between these two recommendations in untreated patients with airflow limitation are missing.

Aims

We aimed to study BDR to salbutamol (SABA) or ipratropium bromide (SAMA) in patients with suspected bronchial asthma or COPD at initial clinical presentation using the 2005 and 2021 criteria and explore clinical factors associated with BDR+.

Methods

Symptomatic, treatment-naïve patients with expiratory airflow limitation (n = 105, 57 men, age (mean ± standard deviation): 65 ± 10 years) underwent BDR testing with 400 mcg salbutamol (day 1) or 80 mcg ipratropium bromide (day 2) and BDR was measured after 15 and 30 minutes. Clinical factors with risk for BDR+ were assessed with binomial logistic regression analysis.

Results

We found a good agreement between the number of 2005-BDR+ and 2021-BDR+ patients at 15 and 30 minutes post-salbutamol and post-ipratropium (88.6-94.8%). More patients showed BDR+ after 30 minutes than following 15 minutes using either criterion. When results at 30 minutes are considered, the number of patients with 2005-BDR+ (82%) was higher than that of 2021-BDR+ (75%), with the proportion of SAMA+ patients being higher than that of SABA+ (2005: 70% vs. 49%, Fisher exact p < 0.01; 2021: 64% vs. 41%, p = 0.001). 2005-BDR+ and 2021-BDR+ to SABA were associated with decreasing pre-BD FEV1% predicted and the presence of cough. More patients with asthma were in the SABA+ group compared to the SAMA+ group (2005: 71% vs. 53%, Fischer exact p = 0.04; 2021: 77% vs. 52%, p = 0.02).

Conclusions

Fewer patients show BDR+ according to the 2021 criteria in comparison with the 2005 recommendations, and protocols for BDR testing may consider the assessment of response to both SABA and SAMA after 30 minutes.

A comparative study of bronchodilator response: utilizing pre-bronchodilator versus predicted normal values

BACKGROUND

A positive bronchodilator response has been defined as a 12% increase in the forced expiratory volume in one second (FEV1) or forced vital capacity (FVC) from their respective pre-bronchodilator values, combined with at least a 0.2 L absolute change. Recent recommendations suggested the use of the percent change in FEV1 and FVC relative to their predicted normal values without having applied them in patients with airflow obstruction. The aim of the current study was to compare the two approaches over a wide range of pre-bronchodilator FEV1 and FVC values.

METHODS

A retrospective review of consecutive patients undergoing spirometry and bronchodilator testing was completed. The change in FEV1 and FVC with a bronchodilator was expressed relative to the pre-bronchodilator and predicted normal FEV1 and FVC.

RESULTS

In 1,040 patients with a non-paradoxical change in FEV1, 19.0% had a ≥ 12% change in FEV1 using their pre-bronchodilator value compared to 5.7% using their predicted normal value. For FVC, the respective values were 12.7% vs. 5.8%. The difference was retained in patients with a ≥ 0.2 L change in FEV1 or FVC. In unobstructed patients, the upper threshold (two standard deviations above the mean) of the bronchodilator response was 14% for FEV1 and 10% for FVC using predicted normal values.

CONCLUSIONS

Expressing the percent change in FEV1 and FVC relative to predicted normal values reduces the over-estimation of the bronchodilator response, especially in patients with a very low pre-bronchodilator FEV1, including in those with a ≥ 0.2 L change in FEV1. Irrespective of pre-bronchodilator values, a ≥ 14% change in FEV1 and ≥ 10% change in FVC relative to the predicted normal values could be considered a positive bronchodilator response.