The goal of this observational study is to understand the genetic and molecular risk factors for developing critical illness in adult intensive care unit (ICU) patients in Sweden. The main questions it aims to answer are:

Which genetic variants are associated with increased risk of critical illness from conditions such as infections, sepsis, and organ failure?

Can circulating proteins and metabolites mediate the effect of genetic risk factors on the severity of illness?

Participants will:

Provide blood samples at ICU admission and again 3-6 months after discharge Consent to genetic analysis and data linkage with national health registries

Have their ICU treatment and outcomes followed using registry and clinical data

This study aims to build a national infrastructure for rapid sample collection and analysis that can also support research in future pandemics.

Inclusion Criteria:

• Adults admitted to intensive care in Sweden

Exclusion Criteria:

• Non adults
• Not admitted to intensive care

Any patient admitted to intensive care at a hospital in Sweden

Swedish legal requirements preclude sharing individual patient data. Patient data access for collaborators is provided on a secure system.