Inclusions were suspended due to the COVID-19 pandemic, and the inclusion rate would not increase during the resumption.

This study aims to estimate the association between blood fibrocytes measured during a suspected exacerbation and 3-year decline forced expiratory volume in one second (FEV1), in patients with Chronic obstructive pulmonary disease (COPD) in primary care, with a history of smoking, independently of the number of exacerbations and of tobacco or occupational exposure.

COPD is highly prevalent in primary care. It is associated with tobacco smoke or toxic occupational exposure. Some COPD patients will experience a faster decline in quality of life and lung function. There is currently no prognostic marker allowing to identify those patients at higher risk of fast lung function decline. Recent data suggest that fibrocytes are involved in COPD's physiopathology. A higher blood fibrocytes level during an acute exacerbation has been associated with higher mortality in COPD patients at a late stage of the disease. In mice, fibrocytes role in lung function decline has been demonstrated at an early stage. To date, association between blood fibrocytes during an exacerbation and lung function decline has not been evaluated at the early stage of COPD in humans.

This study aims to estimate the association between blood fibrocytes measured during a suspected exacerbation and 3-year decline in forced expiratory volume in one second (FEV1), in patients with COPD in primary care, with a history of smoking, independently of the number of exacerbations and of tobacco or occupational exposure.

In this study, blood fibrocytes during a suspected exacerbation will be measured at inclusion. The lung function (FEV1) will be assessed at follow-up visits at 2 months, 12 months and 36 months after inclusion. COPD-related health status and severity of dyspnea will be assessed with COPD Assessment test (CAT) and the modified Medical Research Council dyspnea scale (mMRC) at follow-up visits at 2 months, 12 months and 36 months after inclusion.

Inclusion Criteria:

• man or woman aged more than 40 years old,
• with tobacco exposure of more than 20 pack-years,
• Presenting to a General Practitioner with a suspected mild or moderate COPD exacerbation according to Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines (worsening of symptoms with the need for prescribing short acting bronchodilatators, antibiotics or oral corticosteroids)
• Informed consent given
• Affiliated to a social insurance scheme

Exclusion Criteria:

• Severe exacerbation of COPD according to GOLD guidelines (patient requires hospitalization or visits to the emergency room),
• More likely differential diagnosis than a COPD exacerbation, such as pneumonia, acute pulmonary oedema or other differential diagnosis,
• history of asthma, pulmonary fibrosis, primary pulmonary hypertension or chronic viral infections (HIV, hepatitis)
• person under care or protection of vulnerable adults

Man or woman aged more than 40 years old with tobacco exposure of more than 20 pack-years, Presenting to a General Practitioner with a suspected mild or moderate COPD exacerbation according to GOLD guidelines (worsening of symptoms with the need for prescribing short acting bronchodilatators, antibiotics or oral corticosteroids).