Waiting lists or backlog of work build up because demand for work sometimes exceeds our capacity to do that work. Evidence suggests that our capacity to deal with work varies more than the demand. The mismatch is due to variation in both demand for work, and variation in our capacity to deal with it.

Process mapping, along with measurement of demand, capacity, activity and backlog, provides the evidence you need for service improvement. If you don’t understand the processes of care, you risk changing parts of a process which will not improve the service from the patient’s perspective and may actually incur more waits and delays.

Once the process map is complete, the next stage is analysing it by considering the following:

  • Where are the delays, queues and waiting built into the process?
  • Where are the bottlenecks?
  • What are the longest delays?

In order to make the most of patient flow through a healthcare system, it is necessary to address the entire patient process. You need to analyse and understand the capacity, demand, backlog and activity issues wherever there are waiting lists or backlog of work.

What is demand, capacity, activity and backlog?

Demand: All the requests / referrals coming in from all sources and how many resources they need (equipment time, staff time, room time) to be dealt with.

Capacity: Resources available to do work. For example, the number of pieces of equipment available multiplied by the hours of staff time available to run it.

Activity: All the work done. This does not necessarily reflect capacity or demand on a day to day basis. The activity or the work done on a Monday may be the result of some of Monday’s demand (i.e. emergency) and the previous week’s demand. The capacity is the capacity available on the Monday but activity is often less than available capacity (ideally 80% of available capacity)

Backlog: Previous demand that has not yet been dealt with, showing itself as a backlog of work or a waiting list. It’s logical: if you don’t deal with today’s demand today, there will be a backlog for tomorrow.

Why is measuring demand, capacity, activity and backlog important?

The mismatch or variation in capacity and demand is one of the main reasons why waiting lists or backlogs develop and waiting lists and times increase.