This study aims to enroll chronic critically ill patients in ICU to investigate the epidemiology of chronic critically ill in China and identify risk factors of poor outcomes among those patients. The main question it aims to answer is:

What is the one year mortality of chronic critically ill patients in China? We conduct semi-structured telephone follow-ups to investigate the long-term outcomes of chronic critically ill patients.

Inclusion Criteria:

- Must meet: Age greater than 18 years old; Stay in ICU for 8 days or more.

Meet any of the following criteria:

Tracheotomy; Continuous mechanical ventilation for over 96 hours; Multiple organ failure; Sepsis or severe infection; Severe trauma; Severe brain injury;

Exclusion Criteria:

- Refusing to accept follow-up; Patients who have been lost to follow-up;

This is a prospective cohort study that will consecutively enroll patients meeting the criteria for Chronic Critical Illness (CCI) from the Intensive Care Units of several hospitals in China over a one-year period starting March 2025.