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Length of stay in hospital

Average length of stay for selected conditions or procedures

This page explains the average length of stay measure used on this website and describes how the measure is calculated.

The average length of stay for a patient is the average number of days between admission and separation. MyHospitals presents average length of stay information relating only to overnight stays at public hospitals, for selected conditions and procedures. These are defined using the Australian Refined Diagnosis Related Group (AR-DRG) system version 6.0x, as follows:

Condition/procedure name AR-DRG code
Chronic Obstructive Pulmonary Disease with complications E65A
Chronic Obstructive Pulmonary Disease without complications E65B
Heart Failure with complications F62A
Heart Failure without complications F62B
Appendix removal G07B
Gallbladder removal H08B
Hip replacement I03B
Knee replacement I04B
Cellulitis J64B
Kidney and urinary tract infections with complications L63A
Kidney and urinary tract infections without complications L63B
Prostate removal M02B
Hysterectomy N04B
Gynaecological reconstructive procedures N06B
Caesarean delivery O01C
Vaginal delivery O60B

Average length of stay is reported for conditions and procedures without complications unless otherwise specified.

Hospital peer groups

Hospital peer grouping allows comparisons that reflect the purpose, resources and role of each hospital.

The hospital peer groups used on MyHospitals for average length of stay comparisons are based on the 2015 Australian hospital peer groups (AIHW, 2015). The following peer groups have been used:

MyHospitals groups AIHW 2015 hospital peer groupings
Major hospitals Principal referral
Large hospitals Public acute group A
Medium hospitals Public acute group B and public Women’s hospitals
Small hospitals Public acute group C
Children's hospitals Public Children's hospitals and public Combined women's and children's hospitals

Hospitals that are not included in the above categories are considered ‘Unpeered’ in MyHospitals reports. ‘Unpeered’ hospitals are a diverse group of specialised hospitals, sub and non-acute hospitals, small hospitals and clinics.


Peer group results are only presented if there were more than 2 hospitals with stays for that condition or procedure in the peer group.

For each condition or procedure

Average length of stay

Data source

National Hospital Morbidity Database (NHMD).

About the measure

The average (mean) bed days for overnight stays at a public hospital for a given Australian Refined Diagnosis Related Group (AR-DRG).

Calculating the measure

‘Number of overnight stays’ refers to the number of stays that begin and end on different dates. A stay in hospital may be a complete hospital stay (to discharge, transfer, or death), or a part of the stay if there was a change of care type (for example from acute care to rehabilitation).

‘Total overnight patient bed days’ refers to the sum of the days from the beginning to the end of the stay, for overnight stays.

The average length of stay is calculated as the number of patient bed days for overnight stays divided by the number of overnight stays. The calculation excludes people who were transferred to another health care facility within two days, and people who died in hospital.

Only data which met certain criteria are included in the calculation. The criteria for calculating and presenting results are:

  • Stays for acute care
  • Stays that begin and end on different dates
  • 50 or more overnight stays in the category (in the denominator)

After all the above rules were applied, a small number of exceptionally long stays were excluded as outliers, using this formula:

Outlier bound = 75th percentile + 10 * (75th percentile - 25th percentile)

Stays longer than the outlier bound were excluded. Stays had to be longer than 20 days to be classed as outliers.

Additional information on data quality (including efforts to improve data quality) can be found in Admitted patient care 2016–17: Australian hospital statistics (AIHW, 2018).