Understanding Variation and Setting Capacity

Why do we get backlog and queues?

• Because demand exceeds activity

• Because we want to be efficient

• Because we do not take account of variation

• variation in demand• variation in capacity• the interaction between the two

3

GP Discharged!

Staff

skills

illness holiday

motivation

trainingshifts

Patients

Kit

Process

rooms not the same

supplies

machines not the same

age

sex

race education

motivation

diseaseunclear

guidelines differ

complications anaesthetics

80% is under ourcontrol

Information

transcription

transport

applications

Sources of variation in a clinical system

What variability?• GP

– Number of patients– Number of problems– Investigations– Length of appointments

• Outpatients– Number of referrals– Number of staff– Investigations needed– Length of consultation

What variability?• Ward

– Length of pre-admission stay– Length of post-op stay– Intensity of nursing required– Staffing levels

• Theatre– Number of cases– Length of cases– Anaesthetic time– Recovery time– Turnaround time

Sources of variation activity

• Identify examples of variation in your specialty

Bed availability - an example of theproblem of variation

IN-PATIENT STAYADMISSION DISCHARGE

Variation in patient pathways and

processes. E.g. in Length of Stay

Variation in Admission Patterns

- particularly for Elective Care

Variation in Discharge - By time of day- By day of week

- Seasonal variations

IN-PATIENT STAYADMISSION DISCHARGE

Variation in patient pathways and

processes.E.g. in Length of Stay

Variation in Admission Patterns -

particularly for Elective Care

Variation in Discharge - By time of day- By day of week

- Seasonal variations

“We always bring our hips in on Tuesday !”

IN-PATIENT STAYADMISSION DISCHARGE

Variation in patient pathways and

processes.E.g. in Length of Stay

Variation in Admission Patterns

- particularly for Elective Care

Variation in Discharge - By time of day- By day of week

- Seasonal variations

“We’re too busy in the morning and haven’t time to think about discharges.

They all get done in the afternoon.

Emergency Demand - Decision to admit/hour

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Understanding demand and capacity by hour of the day

Discharged patients/hour

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Emergency & Elective Admissions April-November 2002

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Demand Capacity

Queue

Can’t pass unused capacity forward to next week

Variation mismatch = queue

How should we set capacity?

• Set capacity to average demand?

• Set capacity to maximum demand?

• Something else?

Setting capacity to Average demand

Wait

Seen

Capacity set as average demand

100% utilisation each day= very efficient as long as there is a queueLots of energy shuffling the queuesHigh risk if we get it wrong(clinical and financial)

Setting capacity to max demand

Poor utilisation

Large amount of wasted clinic timeVery inefficient use of resources

Wait

Seen

Capacity set as maximum demand

Solution:Flex Capacity

See today’s work today

But how do we cope with the variation in workload from day to day?

Solution:Reduce variation

Step 1:Understand why capacity and demand vary. Find the root cause

Step 2:Reduce the variation

Step 3:Set capacity to the 80th percentile (not the average)

Step 4:Flex capacity to match demand

Or

80th percentile...

50th percentil

e(median)

80th percentil

e

Variation

Lowestvalue

Highestvalue

Mean

80% of what?

• 80% of the demand falls below the line:• sort the patients/clinics into order• draw the line where 80% of the demand will fall

below, and 20% above the line

• Quick equation:minimum demand+ ((Maximum demand – minimum demand) x 0.8)

=

80% of variation in demand

A model of variability...

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demand waiting list waste

“The Variation Model”For model go to www.steyn.org.uk/models/demand analysis.xls

A new definition of capacity...

• Capacity is not activity

• Capacity is not “100% utilisation of every resource”

• Capacity is maximising utilisation of the constraint

• Capacity should be set at the 80th percentile of the demand