This thesis investigates the survival and long-term outcomes of critically ill COVID-19 patients admitted to intensive care units (ICUs) in the Skåne region of Sweden between May 2020 and May 2021. We aimed to address knowledge gaps by conducting a prospective, multicentre cohort study following 498 ICU patients over three years, evaluating mortality, functional, physical, and mental outcomes, as well as Health-Related Quality of Life (HRQoL) and disease severity biomarkers