Epidemiology of Asthma-Chronic Obstructive Pulmonary Disease Overlap

Asthma COPD Overlap has consistently reported to be associated with an increase burden of disease but the impact on lung function decline and mortality varies by study. The prevalence increases with age but the relationship with gender also varies with the study population. The variability in the prevalence and clinical characteristics of ACO is linked to differences in how chronic obstructive pulmonary disease (COPD) and asthma are defined, including diagnostic criteria (spirometry-based vs. clinical or symptom-based diagnoses vs. claims data), the population studied, the geographic region and environment and a consensus approach to the diagnosis of ACO is needed to allow meaningful and consistent epidemiologic information to be generated about this condition.

Airway and parenchymal transcriptomics in a novel model of asthma and COPD overlap

BACKGROUND

Asthma and chronic obstructive pulmonary disease (COPD) are common chronic respiratory diseases, and some patients have overlapping disease features, termed asthma-COPD overlap (ACO). Patients characterized with ACO have increased disease severity; however, the mechanisms driving this have not been widely studied.

OBJECTIVES

This study sought to characterize the phenotypic and transcriptomic features of experimental ACO in mice induced by chronic house dust mite antigen and cigarette smoke exposure.

METHODS

Female BALB/c mice were chronically exposed to house dust mite antigen for 11 weeks to induce experimental asthma, cigarette smoke for 8 weeks to induce experimental COPD, or both concurrently to induce experimental ACO. Lung inflammation, structural changes, and lung function were assessed. RNA-sequencing was performed on separated airway and parenchyma lung tissues to assess transcriptional changes. Validation of a novel upstream driver SPI1 in experimental ACO was assessed using the pharmacological SPI1 inhibitor, DB2313.

RESULTS

Experimental ACO recapitulated features of both asthma and COPD, with mixed pulmonary eosinophilic/neutrophilic inflammation, small airway collagen deposition, and increased airway hyperresponsiveness. Transcriptomic analysis identified common and distinct dysregulated gene clusters in airway and parenchyma samples in experimental asthma, COPD, and ACO. Upstream driver analysis revealed increased expression of the transcription factor Spi1. Pharmacological inhibition of SPI1 using DB2313, reduced airway remodeling and airway hyperresponsiveness in experimental ACO.

CONCLUSIONS

A new experimental model of ACO featuring chronic dual exposures to house dust mite and cigarette smoke mimics key disease features observed in patients with ACO and revealed novel disease mechanisms, including upregulation of SPI1, that are amenable to therapy.

Asthma-chronic obstructive pulmonary disease overlap and cost-related medication non-adherence among older adults in the United States

BACKGROUND

Cost-related medication non-adherence (CRN) can negatively impact health outcomes in older adults with asthma and chronic obstructive pulmonary disease (COPD) overlap (ACO) by reducing access and adherence to essential medications. The objective of this study is to examine the association of ACO to any CRN and specific forms of CRN among a nationally representative sample of older (age ≥ 65 years) adults.

METHODS

We adopted a cross-sectional study design using data from pooled cross-sectional Medicare Current Beneficiary Surveys (MCBS) (2006-2013) and linked fee-for-service Medicare claims. Unadjusted and adjusted logistic regressions that accounted for the complex survey design examined the association of ACO to any CRN and specific forms of CRN.

RESULTS

Among older adults with ACO, 16% reported any CRN. The most common form of CRN was "failing to get prescription". As compared to older adults with no asthma and no COPD, those with ACO were more likely to report any CRN (adjusted odds ratios [AOR] = 1.50, 95%CI = [1.14, 1.96]) and all forms of CRN. However, when the number of unique medications was added to the model, there were no statistically significant differences in CRN between the two groups.

CONCLUSIONS

Older adults with ACO represent a vulnerable population with increased risk for CRN. Multiple factors can contribute to CRN including: a higher number of prescribed medications, multiple co-morbidities, and cost of therapies. Medication comprehensive review interventions have the potential of reducing the risk of CRN among the older Medicare beneficiaries with ACO.

Clinical characteristics of eosinophilic COPD versus COPD patients with a history of asthma

Eosinophilic COPD appears to be a distinct patient subgroup with an increased corticosteroid response. Eosinophilic COPD has been labelled as part of the asthma COPD overlap syndrome (ACOS). We compared the clinical characteristics of eosinophilic COPD patients (without any clinical history of asthma) and COPD patients with a childhood history of asthma. COPD patients with asthma were characterised by more allergies and more exacerbations, but less eosinophilic inflammation. While terms such as "ACOS" are used to "lump" patients together, we report distinct differences between eosinophilic COPD and COPD patients with asthma, and propose that these groups should be split rather than lumped.