Signature
D = 365 * B * o / L_bar
| Inputs | Definition | Unit |
|---|---|---|
B | Number of staffed (active) beds, available every day of the year | beds |
o | Occupied bed-days divided by available bed-days (365 times B) | proportion from 0 to 1 |
L_bar | Mean length of stay of the discharges, on the same bed-day definition as o | days per discharge |
D | Number of discharges in a year | discharges per year |
|---|
Function
Average length of stay calculation and bed-day costing function
Maps the bed-days and discharges of a period to the average length of stay (ALOS), and relates length of stay to bed capacity, payment trim points, a case-mix adjusted comparison and the cost of an admission or of a change in stay. The records follow the notation of the Average Length of Stay article, where L_bar is the average stay in days and N the number of discharges.
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Implementations
Excel
Annual discharges from beds, occupancy and stay in one cell
Excel multiplies 365 by the named cells for staffed beds and occupancy, and divides by the named ALOS cell.
=365*Beds*Occupancy/ALOS
Assumptions
Steady state over the year for bed throughput
Beds, occupancy and the average stay are stable across the year, and bed-days are counted on one definition in o and L_bar. With seasonal peaks or a changing bed stock the identity holds only for annual totals.
Throughput is potential capacity, not demand
The identity gives the discharges the beds can support at that occupancy. Whether shorter stays turn into more discharges depends on demand, staffing and the beds actually kept open.
Worked examples
Illustrative 100-bed unit at 85% occupancy and a 5-day stay
Illustrative figures: 100 beds at an occupancy of 0.85 provide 31,025 occupied bed-days a year, which at an ALOS of 5 days support 6,205 discharges.
B = 100; o = 0.85; L_bar = 5; D = 6205
Same illustrative unit with the stay halved to 2.5 days
With the same beds and occupancy, halving ALOS to 2.5 days doubles potential discharges to 12,410 a year.
B = 100; o = 0.85; L_bar = 2.5; D = 12410
Common errors
Entering bed occupancy as a percentage
Entering occupancy as 85 rather than 0.85 multiplies the discharges by 100, giving 620,500 a year for the illustrative 100-bed unit instead of 6,205.
Sources
Definitions of bed occupancy, bed turnover and average length of stay
Aloh HE, Onwujekwe OE, Aloh OG, Nweke CJ. Is bed turnover rate a good metric for hospital scale efficiency? A measure of resource utilization rate for hospitals in Southeast Nigeria. Cost Effectiveness and Resource Allocation. 2020;18:21. Methods: occupancy is occupied bed-days over active bed-days (active beds times 365), ALOS is occupied bed-days over discharges, and bed turnover is discharges in one year over active beds. The identity follows from combining the three.
Canonical Identity
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