To determine the overall prevalence of postoperative delirium (POI) and its association with different risk factors in order to establish prevention plans to reduce its incidence and/or duration in Spanish hospitals.

To this end, patients over 18 years of age who underwent urgent and scheduled surgery requiring hospital admission under any type of anaesthesia during two specific days will be recruited and pre-, intra- and postoperative data will be collected.

Inclusion Criteria:

• Patients over 18 years of age undergoing urgent and scheduled surgery requiring hospital admission, under any type of anaesthesia.

Exclusion Criteria:

• Presence of pre-surgical delirium.
• Outpatient surgery.

Patients over 18 years of age undergoing urgent and scheduled surgery requiring hospital admission, under any type of anaesthesia.