The main objective of this RE-SAMPLE cohort study is to identify from a real-world data (RWD) set that will be collected, a subset of data that can be potentially used as important predictors and parameters for disease progression of COPD and complex chronic conditions, and multi-morbid exacerbations. The secondary objective is to evaluate the feasibility of RWD collection from a patient's perspective.

Study design: This is a prospective observational cohort study to collect RWD in patients with COPD and complex chronic conditions, with a maximum of 38 months of follow-up. Measurements are performed and RWD are collected by using the Healthentia mobile phone application at baseline (e.g. patient characteristics), daily (e.g. symptom diary), during follow-up visits and at deterioration, and from hospital data (e.g. healthcare visits). The choice of parameters and measurement tools that will be collected during the cohort will be updated every three months during the first year of the cohort (via protocol amendments). These updates are based on citizen-design sessions and on new literature insights. Prognostic models will be developed including predictors derived from the RWD collection.

Inclusion Criteria:

• Clinical diagnosis of COPD according to the GOLD criteria [5] (FEV1 < 80% of the predicted value and FEV1/FVC < 0.70);
• Patients can be included both at stable state and during exacerbation/hospitalization;
• At least one comorbidity:

diabetes mellitus (glucocorticoid-induced, or stable type 1 or 2), chronic heart failure (clinical diagnosis according to the ESC guidelines), ischaemic heart disease (history of myocardial infarction, angina pectoris), active symptoms of anxiety and/or depression (≥11 Hospital Anxiety and Depression Scale , and/or anxiety or depression symptoms being treated at the time of inclusion);

• Under treatment at one of the pilot sites (MST, TUK, GEM);
• >40 years of age;
• Smoker or ex-smoker;
• Able to understand, read and write the language spoken in the country of the pilot site.
• Accessibility to internet;
• Written informed consent from the subject prior to participation.

Furthermore, 25% of the patients should also have ≥ 2 exacerbations, defined as respiratory problems that required a course of oral corticosteroids / antibiotics in the two years preceding study entry; and/or ≥ 1 hospitalisation for respiratory problems in the two years preceding study entry; and/or modified MRC (mMRC) score of 3 or 4 (COPD patients with these scores have a higher chance of exacerbating).

Exclusion Criteria:

• Serious other diseases with a low survival rate;
• Presence of any other active lung disease (e.g., sarcoidosis);
• Severe psychiatric illness, diagnosed by anamnesis;
• Maintenance therapy with antibiotics
• Patients with cognitive impairment (Mini Mental State Examination (MMSE) < 24)

We aim to enroll 710 patients with both COPD and complex chronic conditions over 28 months (July 2021 until October 2023). Patients will be followed-up for a 38-month period (July 2021 until August 2024). These patients will be recruited from one of the three pilot sites (n=263 from Medisch Spectrum Twente, Netherlands); n=263 from Policlinico Universitario Fondazione Agostino Gemelli, Italy; n=184 from Tartu Ülikooli Kliinikum, Estonia.