Observational, prospective, multicenter cohort study with consecutive inclusion of COPD patients. Eligible patients will be those with severe and very severe COPD according to the GOLD 2024 (Global Initiative for Chronic Obstructive Lung Disease) guidelines being followed at participating hospitals. The severity of COPD is related to the exacerbation rate, which in turn is related to the progression of the disease and the occurrence of complications and death. There is no national data on this subgroup.

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) poderão ser usados intercambiavelmente. 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:

• Patients of both sexes, aged 18 years or older, with confirmed COPD according to GOLD 2024: previous or current exposure and spirometry (FEV1/FVC =2 or CAT >=10); or
• GOLD E (>=2 moderate or 1 severe exacerbation - hospitalization); or
• GOLD 3 and 4 (FEV1 <50%).

Exclusion Criteria:

• Advanced fibrosing interstitial lung disease (extent >=50%); and/or
• High-risk pulmonary hypertension (on triple therapy); and/or
• Active cancer - on systemic therapy

Adults of both sexes with severe and very severe COPD being followed up at participating centers - referral hospitals distributed throughout the country. There are plans to include 693 patients from GOLD B, E, 3 and 4, who will be followed up for 12 months.

Qualified researchers can request access to anonymized individual patient-level data from AstraZeneca group of companies sponsored clinical trials via the request portal Vivli.org. All requests will be evaluated as per the AZ disclosure commitment: https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure.

"Yes", indicates that AZ are accepting requests for IPD, but this does not mean all requests will be approved.

AstraZeneca will meet or exceed data availability as per the commitments made to the EFPIA/PhRMA Data-Sharing Principles. For details of our timelines, please refer to our disclosure commitment at https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure.

When a request has been approved AstraZeneca will provide access to the anonymized individual patient-level data via secure research environment Vivli.org. A Signed Data Usage Agreement (non-negotiable contract for data accessors) must be in place before accessing requested information.