Chronic obstructive pulmonary disease (COPD) is prevalent (8-20%) and is one of the leading causes of mortality. In 2019 according to WHO it was the third highest cause of death worldwide. In 2019 in Brazil respiratory diseases (Chapter J in the ICD10) were the third cause of death (176.073) with COPD (J44) accounting for 45.163 deaths (25,6% of respiratory and 3% overall). There is an upward trend for COPD mortality worldwide.

The disease also has a high morbidity leading to impairment in daily activity and quality of life.

Patients with severe and very severe disease are at a higher risk for negative outcomes, including exacerbation (up to 2-3 per patient per year). This in turn increases the risk of future exacerbations and mortality, with heightened risk lasting up to two years after each event. It is impertive to evaluate which sub-groups are at an even higher risk and could be potential targets for intervention.

"The PLATINO study" was conducted on 2004 and evaluated the prevalence of COPD in 5 cities, only one in Brazil - Sao Paulo. As the data is 20 years old it might not reflect the current epidemiological status and might not be representative of Brazil as a whole.

Understanding this population, their clinical and laboratorial characteristics can help identify sub-groups with higher risk and potential for intervention. The current prevalence, causing agent and characteristics are not known in Brazil as well as detailed outcome data.

This is a prospective multicentre cohort, non-interventional study. The design is to have multiple medical centres representing the regions of Brazil. Each region has a different exposure to risk factors like tobacco smoke, biomass burning and environmental pollution, has a different population composition and density, degree of urbanization and education level. There are also some inferred genetic differences due to previous colonization and miscegenation. *CAT (COPD Assessment Test) OU CAAT (Chronic Airway Assesment Test).

The patients will be enrolled in non-random consecutive method and will be followed up for 12 months. There will be on-site visits at inclusion (V0), 6 and 12 months. There will tele-consults at 3 and 9 months to gather relevant clinical data, with special interest at exacerbation.

There will be 8 participating centres in Brazil, representing all 5 regions (North, Northeast, Midwest, Southeast and South). They will be Teaching Hospitals, Regional Reference Hospitals, Tertiary Hospitals or High Complexity Hospitals. The data will be collected on each site and will be adjudicated by the ARO Team.

Inclusion Criteria:

Severe, very severe and symptomaitc COPD, according to GOLD definition: exposure, FEV1/FVC ratio <0,7:

• GOLD B (mMRC>=2, CAT>=10), OR
• GOLD E (>=2 moderate exacerbations or 1 severe), OR
• GOLD 3 and 4 (FEV1 <50%).

Exclusion Criteria:

Severe interstitial lung disease (extent >50% on HRCT), OR Severe pulmonary hypertension (on triple therapy), OR Active cancer - undergoing systemic therapy.

The population of this study will be adult patients, both sexes, with severe and very severe COPD enrolled in the participating centers.