Case Study: Extended Health Clinic

Submitted: 25 Sep 2017

Operations Research Topics: SimulationModelling

Application Areas: Healthcare

Problem Description

This case study extends the Simple Health Clinic – Scheduled Appointments model. The extensions are:

Walk-up patients are triaged before receiving treatment;
After being triaged, some walk-up patients need to have a test performed before seeing a doctor;
Appointment patients arrive at their appointment times +/- a few minutes;
The arrival rate of walk-up patients varies over the day.

The goal of this simulation study is to analyse the average time patients spend:

waiting for treatment; and
in the clinic;

and the average length of the patient queue (which informs waiting room size). This analysis will include a comparison of the walk-up vs scheduled patients.

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Problem Formulation

In order to formulate a simulation model we specify the following components:

Background – problem description
Objectives of the study
Expected benefits
The CM: inputs, outputs, content, assumptions, simplifications’
Experiments to run

Components 1(Background – problem description) and 2 (Objectives of the study) are given in the Problem Description section (see paragraph describing the goal of the simulation study to identify study objectives).

The Expected benefits (component 3) are a virtual environment for evaluating patient waiting times, total time patients spend in the clinic, and the number of patients waiting for treatment. This environment can be used to experiment with changes to the clinic, including a comparison of effects on the waiting times, queue length, etc for the walk-up vs the scheduled patients.

The CM content is specified using the following components:

Component List
Process flow diagram
Logic flow diagram
Activity cycle diagram

Component List

The components of the Extended Health Clinic model are:

Walk-up patients with their (inter)arrival times
Scheduled patients with their appointment times
Triage nurses with their triage times
Test nurses with their testing times
Doctors with their treatment times
Waiting room with its capacity

Process Flow Diagram

Patient Logic Flow Diagram		Doctor Logic Flow Diagrams

Nurse Logic Flow Diagrams

Activity Cycle Diagram

Once the content has been established (note this is usually an iterative process) we can identify the inputs and outputs: appointment times, interarrival times, triage times, test times, treatment times, waiting times for triage, testing, and treatment (i.e., Patient arrives to Nurse triages Patient, Nurse triages Patient to Nurse performs test on Patient, Nurse performs test on Patient to Doctor sees Patient, Nurse triages Patient to Doctor sees Patient, Patient arrives to Doctor sees Patient), total clinic time (Patient arrives to Outside), number in waiting room.

Assumptions are used to define stochasticity (e.g., Exponential interarrivals, Triangular treatment times) and the simplifications keep the system simple (e.g., single doctors and nurses on all day for triage, testing, and treatment, no registration, no prioritisation).

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