Hospital data definitions

Hospital discharge

A hospital discharge is defined as the release of a patient who has been admitted to an in-patient hospital unit and has stayed for at least one night. A person is discharged when treatment has been finalized, either to their home or to another healthcare facility, for further treatment or rehabilitation. Hospital stays which end due to individuals leaving against medical advice or by in-hospital deaths are also counted. Same-day discharges are excluded. The data on discharges cover all types of hospitals, including general hospitals, mental health hospitals and other specialised hospitals.

Bed days

A bed-day is counted as each overnight stay of an in-patient in hospitals. 

Average length of stay (ALOS)

Average length of stay (ALOS) refers to the average number of days in-patients spend in hospital. ALOS is generally measured by dividing the total annual number of bed-days by the number of admissions or discharges during that same period. Day cases are excluded.

Patients treated

In countries where unique identifiers are available for individuals it is possible to count the number of individuals receiving hospital care (patients treated), in addition to the number of discharges. The Nordic countries are among a limited number of countries where this is possible.


Data on diagnoses reflect main diagnoses i.e., the main health conditions for which an individual is admitted to hospital. Diagnoses are classified according to the World Health Organization’s (WHO’s) International Statistical Classification of Diseases and Related Health Problems (ICD), 10th revision. Data are presented using the International Shortlist for Hospital Morbidity Tabulation (ISHMT), a shortlist which has been adopted by WHO Regional Office for Europe, by OECD and by Eurostat, in addition to NOMESCO.
The ISHMT list comprises 149 groups, thus a relatively long list for a traditional table presentation. Therefore, data are published in an abbreviated list based on the full ISHMT list.