Goals of Hokkaido COPD Cohort Studies
Current state and challenges of COPD treatment
Progress in COPD treatment efforts in local communities
Classification of disease types of COPD and realization of tailored treatment
The goals of our study are to create a new COPD classification (phenotype classification) based on high-resolution CT (HRCT) findings and testing of the reversibility of airflow limitation, and to elucidate its clinical characteristics, frequency of acute exacerbation, as well as its natural course and prognosis. It is also our important task to clarify the factors (including gene information) that determine the disease types, and to establish the method of three-dimensional analysis of airways using HRCT images, and to establish a quantification assessment method of pulmonary emphysema lesions as volume.
This study is a multicenter cohort study led by the First Department of Medicine of Hokkaido University Hospital and its affiliated hospitals. Targeted populations are COPD patients for whom the GOLD diagnostic criteria have been met, past or current cigarette smokers, and patients aged 40 or older with informed consent for the study obtained. Examination items include physical findings, interview (medical history, smoking history, concomitant drugs, etc), Quality of Life (QOL) evaluation, and acute exacerbation assessment, pulmonary function testing, high-resolution CT findings (visual evaluation and digital analysis), blood tests (inflammatory response, α1 anti-trypsin, IgE, eosinophil count, etc.), and genetic testing, etc. With regard to analysis by HRCT images, assessment of degree of pulmonary emphysema has been changed from slice evaluation to dimensional evaluation, which provides details about the level of airway lumen and wall thickening.
What has become clear now is the following. Even if a respiratory function test shows similar severe COPD, the degree ofseverity of pulmonary emphysema may vary. In other words, COPD is not equal to pulmonary emphysema (Figure 1). Only 10% of all patients develop chronic bronchitis symptoms such as cough and sputum production, and contrary to our expectations, the results of reversibility test by β2 agonist inhalation showed no relationship to severity of pulmonary emphysema (Figure 2).
We consider the future issues of the Hokkaido COPD cohort study are to identify 'factors that determine disease types,' 'natural course and prognosis by disease type,' 'efficacy of drug by disease type,' 'the role of pulmonary CT testing for diagnosis of disease types,' and on the basis of the study we hope to proceed to individually tailored treatment that best suits the needs of patients.
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