Queue, Demand, Capacity, Variation and Flow Essential measures for clinicians and managers The queue • Queues occur where demand has not been dealt with resulting in a backlog of work. • The main reasons why queues develop is the mismatch between the variation in demand and capacity at specific times The queue • The NHS is a classic queue system • We place patients in queues all the time • some patients are in multiple queues The queue • Every time the demands exceeds the capacity a queue is formed but • Whenever capacity exceeds demand the extra capacity is lost or it is filled from the queue – often at short notice • Filling slots at short notice can lead to longer waiting times and distort clinical priorities Managing the queue - using evidence based tools • Ensure an element of patient choice in the booking process • Use referral information services or referral management services • Ensure waiting list data is accurate • Reduce unnecessary “carve out” Managing the queue • Take unnamed referrals –refer to a service not a clinician • Pool referrals • Pool waiting lists • See people in clinical and date order Defining demand, capacity activity and queue • Demand on the services is all the requests or referrals into the service from all sources • Capacity is all of the resources required to do the work and includes staff and equipment • Activity is the work done, it is the throughput of the system • Backlog is the demand which has not been dealt with – the queue or waiting list Demand and capacity definitions: Waiting list, queue Demand = what we should have done = All requests for a service = what we should do Capacity = what we could do Activity = what we did Measuring demand, capacity activity and queue • Why is it important to understand the four measures of demand, capacity, activity and queue? • To identify the bottleneck or constraint in the care process • To increase capacity at the stage of the process where it will create the greatest outcome • To reduce inappropriate demand to the constraint • To redesign services or plan services Measuring demand, capacity, activity and queue • Must be measured in the same units of time for the same period i.e. hourly, over a 24 hour period, weekly or monthly • It is not possible to compare two or more items unless they are measured in the same unit of time • It is important to compare the four measures on a single graph Measure demand • Multiply the number of patients referred from all sources by the time taken in minutes to process a patient • Understand your demand – what it is (shape) and where it comes from (source) Manage demand • Right person, right place, right time • Understand and manage activity and capacity to meet changes in demand i.e. seasonal variation Measure capacity • Multiply the number of pieces of equipment by the time available in minutes available to the people with the necessary skills to use it Measure activity • Multiply the number of patients processed by the time in minutes it took to process each patient Measure the backlog or queue • Multiply the number of patients waiting by the time it will take in minutes to process a patient Compare the four measures • Convert the data on demand, capacity, activity and backlog or queue onto a common line graph If av. Demand = av. Capacity, variation mismatch = queue Queue Capacity Demand Can’t pass unused capacity forward time demand capacity activity 80% of variation in demand 900 800 700 600 500 400 300 200 100 0 Sep-04 Oct-04 Nov-04 Dec-04 Jan-05 Feb-05 Mar-05 Apr-05 May-05 Jun-05 Jul-05 Aug-05 Understanding flow • In the NHS flow is the movement of patients, information or equipment between departments, staff groups or organisations as part of their pathway of care • Whilst process mapping looks at care processes from the patients perspective, flow analysis looks at the care process from a unit or departmental perspective Flow modelling • Supports service improvement – at specific bottlenecks or constraints, in specific clinical areas, or across whole health systems • This tool will not tell you what should change – process mapping helps with identifying that • Flow modelling will show how well scarce resources are being used and how much room there is for improvement How to build the flow model • Define the patient group to be analysed and define the start and end points of the flow map • In straightforward care processes a process map and process times will provide sufficient information to examine patient flow • The Unscheduled Care Collaborative made extensive use of flow mapping and modelling Understanding variation • Why is it important to understand variation • Because the mismatch between the variation in demand and capacity is one of the main reasons that queues occur in the NHS What variability? • GP – Number of patients – Number of problems – Investigations – Length of appointments What variability? • 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 Variability • Theatre – Number of cases – Length of cases – Anaesthetic time – Recovery time – Turnaround time Bed availability - an example of the problem of variation ADMISSION Variation in Admission Patterns - particularly for Elective Care IN-PATIENT STAY DISCHARGE Variation in patient pathways and processes. E.g. in Length of Stay Variation in Discharge - By time of day - By day of week - Seasonal variations “We always bring our hips in on Tuesday !” ADMISSION Variation in Admission Patterns - particularly for Elective Care IN-PATIENT STAY DISCHARGE Variation in patient pathways and processes. E.g. in Length of Stay Variation in Discharge - By time of day - By day of week - Seasonal variations Understanding demand and capacity by hour of the day Emergency Demand - Decision to admit/hour 6 5 4 3 2 1 Time of day 23 21 19 17 15 13 11 9 7 5 3 0 1 Emergency Demand 7 Discharged patients/hour 12 10 8 6 4 2 Time of day 23 21 19 17 15 13 11 9 7 5 3 0 1 Discharged Patients 14 11/11/2002 28/10/2002 14/10/2002 30/09/2002 16/09/2002 02/09/2002 19/08/2002 05/08/2002 22/07/2002 08/07/2002 24/06/2002 10/06/2002 27/05/2002 13/05/2002 29/04/2002 15/04/2002 01/04/2002 Number of Admissions Emergency & Elective Admissions April-November 2002 60 50 40 30 Emergency Admissions 20 Elective Admissions 10 0 Analysing variation • Statistical Process Control • Two types of variation • Common cause – that which is natural and to be expected • Special cause – which produces unusual or unexpected variation Statistical process control • Two basic charts • The run chart – a line graph – an ideal method of comparing sets of data • The control chart – also run charts but with two distinct differences i.e. Any questions?