Expanded Studies on the SCAPIS Stockholm Reexamination Cohort

The Swedish CArdioPulmonary bioImage Study (SCAPIS) is a unique, large-scale national research initiative involving 30,000 randomly selected individuals aged 50-64, recruited between 2014 and 2018. The study is a collaborative effort among six university hospitals across Sweden. A follow-up study, SCAPIS 2, is conducted for half of the original participants. In Stockholm, 2,500 individuals will be re-examined at Danderyd University Hospital and Karolinska Institutet. SCAPIS 2 includes a core set of examinations involving blood sampling, questionnaires, and imaging. In addition to these, complementary local investigations are conducted to enable more detailed research questions. This protocol describes the additional studies conducted in the Stockholm cohort: EXTENDED SAMPLING: Saliva and Blood Samples with Blood Cell Isolation Additional blood samples will be collected to isolate blood cells for detailed immune system profiling, red blood cell function nd for lipid profiles and inflammatory markers. Saliva samples will be analyzed for inflammatory markers and microbial composition. EXTENDED QUESTIONNAIRES: Dyspnea, Sleep, Respiratory Infections, and Dental Health Participants will complete detailed questionnaires covering recent food, drink, and medication intake; oral hygiene; breathing and lung function; sleep quality and daytime somnolence; and history of respiratory infections, including COVID-19. EXTENDED IMAGING AND PHYSIOLOGICAL MEASUREMENTS: These investigations will be conducted during a separate visit, coordinated with the main study, and take approximately one hour. 1. Cardiac Ultrasound and Abdominal Aortic Measurements: cardiac structure and function, as well as the diameter of major arteries (e.g., the thoracic and abdominal aorta). 2. Liver Elastography: An ultrasound-based technique used to assess liver stiffness and fat content. 3. Vascular Stiffness: Blood pressure cuff-based pulse wave analysis with automated stiffness calculation. Photoplethysmography (PPG) using skin-mounted sensors (commonly used for oxygen saturation monitoring, in cuffless blood pressure monitors and wearables). Single-lead ECG via adhesive electrodes. 4. Valvular and Vascular Calcification: In the main SCAPIS study, CT imaging of the heart and large vessels will be performed. In SCAPIS 2, images will be re-analyzed using algorithms that quantify calcium deposits in heart valves. RESEARCH QUESTIONS Blood and blood cell analyses will be conducted to assess immune activation, lipids and lipid mediators, and immune cell phenotypes. These analyses aim to distinguish chronic from self-limiting cardiovascular inflammation and to detect prevalent, incident, and subclinical cardiovascular disease (CVD) for improved risk assessment. Saliva biomarkers, with a focus on inflammation and oral microbiota, will be studied to explore links between oral health, respiratory health, systemic inflammation, and comorbidities. Survey data on sleep, breathing, respiratory infections, and oral health will be used to investigate associations with liver, lung, and cardiovascular diseases, including their risk factors and prognosis. The prevalence of liver steatosis and fibrosis in the general population wil be examined, along with their associations with CVD and heart failure. It will also be assess whether SCAPIS data can predict liver stiffness. Risk factors for cardiac dysfunction and valvular disease, as well as progression to heart failure will be analyzed. CT-based calcium scoring in the aorta and valves will be studied for associations to valve disease, heart failure, intervention timing, and progression of aortic dilation between SCAPIS 1 and 2. Aortic aneurysm prevalence and risk factors will be evaluated, including associations with SCAPIS variables and incident cardiovascular disease. Infrarenal aortic diameter is also used as a subclinical marker of aortic aneurysm. New techniques using photoplethysmography (PPG) for arterial stiffness and pulse characteristics will be studied in relation to coronary artery disease, cardiac structure and function, valve disease, liver stiffness, biomarkers, and blood pressure. Finally, SCAPIS and SCAPIS 2 data will be integrated including substudy results for comprehensive risk assessment of clinical and subclinical CVD and to guide prevention strategies.