Increased life expectancy leads to population aging, increased morbidities and aging of hospitalized patients. The acquisition of frailty leads to worse outcomes derived from hospitalization, but although frailty has been related to aging, young patients admitted to Intensive Care Units (ICU) with frailty have also been found to have worse outcomes than non-frail patients. This unfavorable evolution could be related to the acquisition of the post-uci syndrome (physical, mental and cognitive sequelae at discharge from the ICU), since high frailty scores favor this syndrome.

The use of frailty scales on admission to the ICU could provide early detection of patients most likely to develop post-ICU syndrome, regardless of age, and redirect our care to those who need it most. Some scales that measure frailty in elderly patients have been used in the ICU, but although they have been validated in their original language, they need to be adapted and validated in Spanish.

Objectives. Adaptation and validation of the Clinical Frailty Scale (CFS) and the FRAIL Scale in ICU patients of different ages, in women and in men.

Methodology. Study developed in two phases.Phase 1, adaptation to Spanish of the scales (translation, pilot, back-translation, correlation); Phase 2, analysis of their metric properties (Validity, Reliability, Sensitivity, Minimum important difference) by means of a multicenter observational study (7 ICUs in Spain), prospective, descriptive, of a cohort of critical patients with one-year follow-up (at 3, 6, 9 and 12 months after hospital discharge).

Inclusion Criteria:

- Critical care patients over 18 years who have given their consent personally.

Exclusion Criteria:

• Patients admitted with a diagnosis of present or imminent brain death,
• readmissions previously included,
• patients whose expected stay is less than 48 hours
• patients with comunication problems

All patients who remain hospitalized for more than 48 hours in any of the 8 Spanish intensive care units participating in the study, they will be candidates for inclusion in the study.