Overlap between asthma and COPD

Asthma and Chronic Obstructive Pulmonary Disease Overlap: The Effect of Definitions on Measures of Burden

Background: Although the overlap between asthma and COPD has been recognized for years this overlap has only recently been given a name, asthma-COPD overlap syndrome (ACOS), and better defined. Different definitions of the component diseases can affect prevalence and outcome measures of ACOS. Methods: We used data from the National Health and Nutrition Examination Survey (NHANES) from 2007-2012 to determine the population estimates of ACOS in U.S. adults using 2 different definitions of ACOS (ACOS1= self-reported COPD and current asthma; ACOS2 = spirometric-confirmed COPD [pre-bronchodilator FEV₁/FVC < 70%] and current asthma) and to describe variation in other factors, such as lung function impairment and health care utilization, by ACOS definitions. Results: Among U.S. adults aged 20 and older, 1.6% had ACOS1, and 1.9% had ACOS2. Both case definitions were similar with regard to symptoms and impairment of lung function. ACOS1 individuals were more likely to have one or more overnight hospital stays relative to those with neither asthma nor COPD, (odds ratio [OR] 3.4, 95% confidence interval [CI] 2.5, 4.6) than ACOS2 (OR 1.6, 95% CI 0.9, 2.9). Conclusions: Different definitions of ACOS in population-based studies affect both estimates of disease prevalence and outcomes related to the disease. These definitions need to be carefully considered in the design of epidemiologic studies and clinical trials.

Evaluation of atopy in patients with COPD

OBJECTIVE

To determine the prevalence of atopy and to evaluate clinical, laboratory, and radiological profiles in patients with COPD.

METHODS

This was a cross-sectional study involving outpatients with stable COPD (defined by the clinical history and a post-bronchodilator FEV1/FVC < 70% of the predicted value). The patients completed a questionnaire regarding clinical characteristics and atopy, after which they underwent nasal lavage cytology, skin prick testing, chest X-rays, arterial blood gas analyses, and determination of total serum IgE.

RESULTS

Of the 149 subjects studied, 53 (35.6%), 49 (32.8%), and 88 (59.1%) presented with nasal eosinophilia, a positive skin prick test result, and symptoms of allergic rhinitis, respectively. Correspondence analysis confirmed these findings, showing two distinct patterns of disease expression: atopy in patients with COPD that was less severe; and no evidence of atopy in those with COPD that was more severe (reduced FEV1 and hyperinflation). There was a statistically significant association between nasal eosinophilia and a positive bronchodilator response.

CONCLUSIONS

Using simple and reproducible methods, we were able to show that there is a high frequency of atopy in patients with COPD. Monitoring inflammation in the upper airways can be a useful tool for evaluating respiratory diseases in the elderly and in those with concomitant asthma and COPD, a clinical entity not yet fully understood.