Old dilemma: asthma with irreversible airway obstruction or COPD

Airway smooth muscle area to predict steroid responsiveness in COPD patients receiving triple therapy (HISTORIC): a randomised, placebo-controlled, double-blind, investigator-initiated trial

BACKGROUND

Although inhaled corticosteroids (ICS) are highly effective in asthma, they provide significant, but modest, clinical benefit in COPD. Here, we tested the hypothesis that high bronchial airway smooth muscle cell (ASMC) area in COPD is associated with ICS responsiveness.

METHODS

In this investigator-initiated and -driven, double-blind, randomised, placebo-controlled trial (HISTORIC), 190 COPD patients, Global Initiative for Chronic Obstructive Lung Disease stage B-D, underwent bronchoscopy with endobronchial biopsy. Patients were divided into groups A and B, with high ASMC area (HASMC: >20% of the bronchial tissue area) and low ASMC area (LASMC: ≤20% of the bronchial tissue area), respectively, and followed a run-in period of 6 weeks on open-label triple inhaled therapy with aclidinium (ACL)/formoterol (FOR)/budesonide (BUD) (400/12/400 μg twice daily). Subsequently, patients were randomised to receive either ACL/FOR/BUD or ACL/FOR/placebo and followed for 12 months. The primary end-point of the study was the difference in post-bronchodilator forced expiratory volume in 1 s (FEV1) over 12 months between patients with LASMC and HASMC receiving or not receiving ICS.

RESULTS

In patients with LASMC, ACL/FOR/BUD did not significantly improve FEV1 over 12 months, as compared to ACL/FOR/placebo (p=0.675). However, in patients with HASMC, ACL/FOR/BUD significantly improved FEV1, as compared to ACL/FOR/placebo (p=0.020). Over 12 months, the difference of FEV1 change between the ACL/FOR/BUD group and the ACL/FOR/placebo group was 50.6 mL·year-1 within the group of patients with LASMC and 183.0 mL·year-1 within the group of patients with HASMC.

CONCLUSION

COPD patients with ΗASMC respond better to ICS than patients with LASMC, suggesting that this type of histological analysis may predict ICS responsiveness in COPD patients receiving triple therapy.

Bronchodilator Response in FVC Is Larger and More Relevant Than in FEV1 in Severe Airflow Obstruction

BACKGROUND

Recommendations on interpreting tests of bronchodilator responsiveness (BDR) are conflicting. We investigated the dependence of BDR criteria on sex, age, height, ethnicity, and severity of respiratory impairment.

METHODS

BDR test data were available from clinical patients in the Netherlands, New Zealand, and the United States (n = 15,278; female subjects, 51.7%) and from surveys in Canada, Norway, and five Latin-American countries (n = 16,250; female subjects, 54.7%). BDR calculated according to FEV₁, FVC, and FEV₁/FVC was expressed as absolute change, a percentage of the baseline level (% baseline), a percentage of the predicted value (% predicted), and z score.

RESULTS

Change (Δ) in FEV₁ and FVC, in milliliters, was unrelated to the baseline value but was biased toward age, height, sex, and level of airways obstruction; ΔFEV₁ was significantly lower in African Americans. In 1,106 subjects with low FEV₁ (200-1,621 mL) the FEV₁ increased by 12% to 44.7% relative to baseline but < 200 mL. Expressing BDR as a percentage of the predicted value or as a z score attenuated the bias and made the 200-mL criterion redundant, but reduced positive responses by half. ΔFEV₁ % baseline increased with the level of airflow obstruction but decreased with severe obstruction when expressed as z scores or % predicted; ΔFVC, however expressed, increased with the level of airflow obstruction.

CONCLUSIONS

Expressing FEV₁ responsiveness as % baseline spuriously suggests that responsiveness increases with the severity of respiratory impairment. Expressing change in FEV₁ or FVC as % predicted or as z scores eliminates this artifact and renders the required 200-mL minimum increase redundant. In severe airways obstruction ΔFVC should be critically evaluated as an index of clinically important relief of hyperinflation, with implications for bronchodilator drug trials.

Airflow obstruction: is it asthma or is it COPD?

Despite the availability of guideline recommendations, diagnostic confusion between COPD and asthma appears common, and often it is very difficult to decide whether the obstruction is caused by asthma or COPD in a patient with airway obstruction. However, there are well-defined features that help in differentiating asthma from COPD in the presence of fixed airflow obstruction. Nonetheless, the presentations of asthma and COPD can converge and mimic each other, making it difficult to give these patients a diagnosis of either condition. The association of asthma and COPD in the same patient has been designated mixed asthma–COPD phenotype or overlap syndrome. However, since the absence of a clear definition and the inclusion of patients with different characteristics under this umbrella term, it may not facilitate treatment decisions, especially in the absence of clinical trials addressing this heterogeneous population. We are realizing that neither asthma nor COPD are single diseases, but rather syndromes consisting of several endotypes and phenotypes, consequently comprising a spectrum of diseases that must be recognized and adequately treated with targeted therapy. Therefore, we must treat patients by personalizing therapy on the basis of those treatable traits present in each subject.

Peripheral killer cells do not differentiate between asthma patients with or without fixed airway obstruction

OBJECTIVE

The three main types of killer cells - CD8⁺ T cells, NK cells and NKT cells - have been linked to asthma and chronic obstructive pulmonary disease (COPD). However, their role in a small subset of asthma patients displaying fixed airway obstruction (FAO), similar to that seen in COPD, has not been explored. The objective of the present study was to investigate killer cell numbers, phenotype and function in peripheral blood from asthma patients with FAO, asthma patients without FAO, and healthy individuals.

METHODS

Peripheral CD8⁺ T cells (CD8⁺CD3⁺CD56^-), NK cells (CD56⁺CD3^-) and NKT-like cells (CD56⁺CD3⁺) of 14 asthma patients with FAO (post-bronchodilator FEV/FVC <0.7, despite clinician-optimised treatment), 7 asthma patients without FAO (post-bronchodilator FEV/FVC ≥ 0.7), and 9 healthy individuals were studied.

RESULTS

No significant differences were seen between the number, receptor expression, MAPK signalling molecule expression, cytotoxic mediator expression, and functional cytotoxicity of peripheral killer cells from asthma patients with FAO, asthma patients without FAO and healthy individuals.

CONCLUSIONS

Peripheral killer cell numbers or functions do not differentiate between asthma patients with or without fixed airway obstruction.

Do we really need asthma-chronic obstructive pulmonary disease overlap syndrome?

The association of asthma and chronic obstructive pulmonary disease (COPD) in the same patient, which is designated as mixed asthma-COPD phenotype or overlap syndrome (ACOS), remains a controversial issue. This is primarily because many conflicting aspects in the definition of ACOS remain, and it is extremely difficult to summarize the distinctive features of this syndrome. Furthermore, we are realizing that asthma, COPD, and ACOS are not single diseases but rather syndromes consisting of several endotypes and phenotypes and, consequently, comprising a spectrum of diseases. The umbrella term ACOS blurs the lines between asthma and COPD and allows an approach that simplifies therapy. However, this approach contradicts the modern concept according to which we must move toward more targeted and personalized therapies to treat patients with these diseases. Therefore we argue that the term ACOS must be abandoned and ultimately replaced when new phenotypes and underlying endotypes are identified and a new taxonomy of airway diseases is generated.