Average length of stay: what it is, how to calculate it and how to reduce it
Every extra day in hospital takes up a bed and consumes resources. Measuring length of stay well is the first step to managing it.
Average length of stay is the average time, in days, that patients remain admitted. It affects cost, bed availability and, in many contracts and in SUS (Brazil's public health system), revenue. That makes it one of the central indicators of bed management.
The formula
Average length of stay = patient-days ÷ discharges
- Patient-days: the sum, over the period, of patients admitted on each day, counted in the census.
- Discharges: total discharges, deaths and external transfers in the period.
The definition follows the Brazilian Ministry of Health's hospital census standard and matches the indicator sheets used by ANS.
Example: a hospital recorded 2,880 patient-days and 640 discharges in the month. Average length of stay was 2,880 ÷ 640 = 4.5 days.
How to read it
- By department: ICU, medical and surgical wards have very different stays. The overall average mixes everything.
- By specialty and procedure: the fair comparison is between similar patients.
- By payer: SUS, private payers and self-pay may have different profiles and rules.
- Against last year and against the target: the trend matters more than a single month.
A common trap: hospitals with many short stays (day hospital, ambulatory surgery) have lower averages, which can hide long admissions elsewhere. Separate these groups.
Why length of stay weighs on the result
- Cost: every day consumes staff, hospitality services, supplies and drugs.
- Revenue: in packages, global daily rates and SUS, revenue does not follow length of stay. Days beyond expectations are cost without revenue. See SUS excess length of stay.
- Capacity: a bed occupied longer is a bed unavailable for a new patient.
Practices to reduce length of stay without harming patients
- Discharge planning from admission: an expected discharge date recorded and reviewed.
- Bed management: a team or committee that reviews patients above the expected stay every day.
- Faster tests and consultations: a delayed test or specialist opinion is one of the most common causes of an extra day.
- Clinical protocols for the most frequent conditions.
- Coordination with the care network: transfers, transitional care and home care for those who no longer need the hospital.
- Recording reasons for delayed discharge, to tackle recurring causes.
How to track it
Track average length of stay by department and payer every month, the list of patients above the expected stay every day, and the relationship with the occupancy rate. For hospitals running Tasy, the dashboards are in patient care dashboards.
Related questions
What is a good average length of stay?
It depends on the hospital profile. For general acute-care hospitals, references in the literature and quality programs usually fall between three and five days, but the useful comparison is by specialty and with the hospital itself over time.
Does an internal transfer between departments count as a discharge?
For the hospital-wide average, no: only external transfers. For each department's average, it is common to count the department's internal discharges, as ICU indicator sheets do.
Does a patient admitted and discharged on the same day count as a patient-day?
Usually yes, as one patient-day. The criterion should be defined and kept.
Written by the team behind Clic Health: accountants, controllers and developers with more than 20 years of work in hospital management.