Background
Context
Simulation modelling in health care
OB/GYN training and economic evaluation models
OB/GYN inpatient delivery models
OB/GYN outpatient models
Other relevant outpatient models
Scheduling
Methods
Aim
Study design and setting
Characteristics of participants
Model specification
Configuration
Data sources
Service | Min | Median | Mean | Max | Standard Deviation | Kurtosis | Skewness |
---|---|---|---|---|---|---|---|
Check In | 0.130 | 0.467 | 0.457 | 1.000 | 0.249 | 2.156 | 0.531 |
Connect CTG | 2.000 | 3.341 | 3.410 | 5.000 | 0.863 | 1.842 | 0.156 |
CTG Scan | 20.000 | 25.557 | 26.250 | 45.000 | 4.855 | 6.011 | 1.558 |
Disconnect CTG | 2.000 | 3.341 | 3.410 | 5.000 | 0.863 | 1.842 | 0.156 |
Consultation | 10.000 | 21.282 | 22.325 | 45.000 | 4.901 | 4.764 | 1.005 |
Check out | 0.130 | 1.580 | 1.589 | 5.000 | 0.985 | 2.696 | 0.480 |
No. of CTG checks | 0.000 | 1.897 | 2.120 | 10.000 | 1.462 | 8.374 | 1.793 |
Assumptions
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The clinic’s midwives and doctors did not attend to other non-clinic women during clinic hours.
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The reception staff and waiting area resources (waiting area chairs and corridor space) are shared with women attending all clinics.
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The midwives are able to attend to multiple women.
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If a woman sees a doctor before a midwife, the woman does not have to see a doctor again after the midwife consultation. It was assumed that the doctor has sufficient information to complete the consultation.
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The clinic will stay open if women still need to use it. Results are collected within and outside clinic hours. In reality staff would have other duties to attend to. The simulation model runs until midnight to treat as many women as possible. Configurations that fail to satisfy the demand in clinic hours are rejected for that level of demand.
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All clinic appointments are attended. This places greater stress on each configuration, as in reality women may miss their appointment as they have given birth prior to it. Therefore all of the results presented are based on the maximum number of women each configuration can serve within clinic opening hours.
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The model does not differentiate between new and returning patients. New patients are those referred to the clinic for their first appointment for the current pregnancy. Returning patients are those attending their second, third etc. appointment for current pregnancy. The service time estimates provided by staff are for all clinic appointments.
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Two simplistic appointment systems are assessed in this paper. That either all of the demand arrives when the clinic opens at 08:00 or half of the demand arrives at 08:00 and half at 08:30. More nuanced appointment systems can be evaluated, but in general if the women arrive they tend to arrive before the clinic opens.
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The queuing discipline currently employed in the model is first in first out (FIFO).
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The model of the clinic operates a single queue multiple server system. Women are not assigned to particular midwives, CTG machines or doctors.
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The model represents the clinic in isolation, and does not take into consideration the occupancy of the maternity ward or operating theatres with respect to induction decision. This is outside the scope of this model.
Validation
Experimental design
Time horizon
Multiple runs
Inputs
Input | Description | Values |
---|---|---|
X0 | Arrivals. The number of women who attend the clinic. | - No default value, it ranges from 2 to 20. Also a Key Performance Indicator (KPI), see next section. |
X1 | Arrivals pattern | - “All”a. All the women arrive at 08:00 - “Half”. Half of the women arrive at 08:00 and half at 08:30 For odd numbers of arrivals the larger value arrives at 08:00. |
X2 | Order of midwife and doctor consultation | - “Doc” a woman can see a doctor first if one is available, before seeing a midwife - “Mid”a the woman sees a midwife before a doctor. |
X3 | Number of midwives | Twoa or three. |
X4 | Number of doctors | Twoa or three. |
X5 | Number of CTGs | Threea or four. |
Key performance indicators
KPI | Description |
---|---|
Y1 | Arrivals. Number of women attending clinic (same as X0, see Optimal Treatment Capacity section) |
Y2a | Time last woman checks out (HH:MM:SS) |
Y3 | Women’s LoS (mins) |
Y4b | Clinic overrun (mins after 10:30) |
Y5 | Women’s midwife waiting time (mins) [CTG connection wait + CTG disconnection wait]. |
Y6 | Women’s doctor waiting time (mins) |
Y7 | Women’s CTG connection waiting time (mins) [CTG wait + midwife wait for connection] |
Optimal treatment capacity
Inputs | Input levels | Cumulative configurations |
---|---|---|
X1: Arrival pattern | 2 | 2 |
X2: Order of midwife and doctor consultations | 2 | 4 |
X3: Number of midwives | 2 | 8 |
X4: Number of doctors | 2 | 16 |
X5: Number of GTGs | 2 | 32a |
X0: Arrivals | 19 | 608b |
Results
Group | Purpose | Midwives (X3) | Doctors (X4) | CTGs (X5) |
---|---|---|---|---|
0 | The base case. The number of resources currently available. | 2 | 2 | 3 |
1 | Evaluates the effect of one extra midwife. | 3 | 2 | 3 |
2 | Evaluates the effect of one extra doctor. | 2 | 3 | 3 |
3 | Evaluates the effect of one extra midwife and doctor. | 3 | 3 | 3 |
4 | Evaluates the effect of one extra CTG machine. | 2 | 2 | 4 |
5 | Evaluates the effect of one extra midwife and one extra CTG machine. | 3 | 2 | 4 |
6 | Evaluates the effect of one extra doctor and one extra CTG machine. | 2 | 4 | 4 |
7 | Evaluates the effect of one extra midwife. | 3 | 3 | 4 |
Subgroup | Description | X1 | X2 |
---|---|---|---|
a | The base case. All women arrive at 08:00 and they all see the midwife before seeing the doctor. | “All” | “Mid” |
b | Half the women arrive at 08:00 and half at 08:30 and they all see the midwife before seeing the doctor. | “Half” | “Mid” |
c | All the women arrive at 08:00 and they can see a doctor first if a doctor is free. | “All” | “Doc” |
d | Half the women arrive at 08:00 and half at 08:30 and they can see a doctor first if a doctor is free. | “Half” | “Doc” |
Inputs | Key performance indicators | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Configuration | X1 – Arrivals at 8:00 | X2 – Midwife or doctor first | X3 – Midwives | X4 – Doctors | X5 – CTGs | X0/Y1 – Arrivals / Treatment capacity (women) | Y2 Time last woman checks out (CI in seconds) | Y3 Women’s LoS (minutes) | Y4 Clinic overrun (minutes) | |||
Mean | ± | Mean | ± | Mean | ± | |||||||
0a | All | Mid | 2 | 2 | 3 | 7 | 10:25:33 | 11 | 102.97 | 0.21 | 2.00 | 0.09 |
0b | Half | Mid | 2 | 2 | 3 | 7 | 10:25:36 | 10 | 90.13 | 0.14 | 2.03 | 0.09 |
0c | All | Doc | 2 | 2 | 3 | 8 | 10:18:18 | 12 | 98.66 | 0.15 | 0.81 | 0.06 |
0d | Half | Doc | 2 | 2 | 3 | 8 | 10:22:29 | 11 | 86.06 | 0.10 | 1.27 | 0.07 |
1a | All | Mid | 3 | 2 | 3 | 7 | 10:21:17 | 10 | 99.72 | 0.20 | 0.76 | 0.05 |
1b | Half | Mid | 3 | 2 | 3 | 7 | 10:21:26 | 10 | 86.99 | 0.13 | 0.78 | 0.05 |
1c | All | Doc | 3 | 2 | 3 | 9 | 10:27:00 | 11 | 101.47 | 0.16 | 2.49 | 0.09 |
1d | Half | Doc | 3 | 2 | 3 | 9 | 10:28:58 | 10 | 91.41 | 0.09 | 3.18 | 0.11 |
2a | All | Mid | 2 | 3 | 3 | 7 | 10:23:44 | 11 | 99.90 | 0.20 | 1.67 | 0.08 |
2b | Half | Mid | 2 | 3 | 3 | 7 | 10:23:46 | 12 | 87.15 | 0.14 | 1.67 | 0.08 |
2c | All | Doc | 2 | 3 | 3 | 9 | 10:22:13 | 13 | 100.08 | 0.16 | 1.84 | 0.09 |
2d | Half | Doc | 2 | 3 | 3 | 9 | 10:27:44 | 12 | 88.64 | 0.11 | 3.22 | 0.12 |
3a | All | Mid | 3 | 3 | 3 | 8 | 10:27:30 | 10 | 101.59 | 0.21 | 2.37 | 0.09 |
3b | Half | Mid | 3 | 3 | 3 | 8 | 10:29:13 | 10 | 87.72 | 0.14 | 3.04 | 0.10 |
3c | All | Doc | 3 | 3 | 3 | 9 | 10:12:28 | 10 | 95.33 | 0.14 | 0.19 | 0.03 |
3d | Half | Doc | 3 | 3 | 3 | 9 | 10:23:38 | 11 | 86.15 | 0.10 | 1.34 | 0.07 |
4a | All | Mid | 2 | 2 | 4 | 8 | 10:28:21 | 12 | 105.93 | 0.20 | 3.31 | 0.12 |
4b | Half | Mid | 2 | 2 | 4 | 8 | 10:28:33 | 12 | 91.09 | 0.13 | 3.47 | 0.12 |
4c | All | Doc | 2 | 2 | 4 | 9 | 10:16:35 | 14 | 99.86 | 0.13 | 1.10 | 0.07 |
4d | Half | Doc | 2 | 2 | 4 | 9 | 10:18:38 | 13 | 88.64 | 0.09 | 1.24 | 0.08 |
5a | All | Mid | 3 | 2 | 4 | 8 | 10:22:16 | 10 | 101.57 | 0.19 | 0.99 | 0.06 |
5b | Half | Mid | 3 | 2 | 4 | 8 | 10:22:23 | 10 | 86.71 | 0.11 | 1.03 | 0.06 |
5c | All | Doc | 3 | 2 | 4 | 10 | 10:24:36 | 12 | 100.28 | 0.14 | 1.94 | 0.09 |
5d | Half | Doc | 3 | 2 | 4 | 10 | 10:26:10 | 11 | 88.27 | 0.10 | 1.99 | 0.09 |
6a | All | Mid | 2 | 3 | 4 | 8 | 10:17:27 | 14 | 99.49 | 0.18 | 1.34 | 0.08 |
6b | Half | Mid | 2 | 3 | 4 | 8 | 10:17:25 | 14 | 84.57 | 0.11 | 1.30 | 0.08 |
6c | All | Doc | 2 | 3 | 4 | 11 | 10:28:38 | 14 | 104.54 | 0.15 | 4.24 | 0.16 |
6d | Half | Doc | 2 | 3 | 4 | 10 | 10:21:54 | 14 | 86.55 | 0.10 | 2.18 | 0.11 |
7a | All | Mid | 3 | 3 | 4 | 10 | 10:29:03 | 10 | 103.05 | 0.18 | 2.83 | 0.10 |
7b | Half | Mid | 3 | 3 | 4 | 10 | 10:29:05 | 9 | 88.04 | 0.12 | 2.84 | 0.10 |
7c | All | Doc | 3 | 3 | 4 | 12 | 10:27:43 | 10 | 101.30 | 0.14 | 2.39 | 0.09 |
7d | Half | Doc | 3 | 3 | 4 | 11 | 10:21:57 | 10 | 85.47 | 0.08 | 1.00 | 0.06 |
Inputs | Key performance indicators | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Configuration | X1 – Arrivals at 8:00 | X2 – Midwife or doctor first | X3 – Midwives | X4 – Doctors | X5 – CTGs | X0/Y1 – Arrivals / Treatment capacity (women) | Y5 Women’s midwife waiting time (minutes) | Y6 Women’s doctor waiting time (minutes) | Y7 Women’s CTG connection waiting time (minutes) | |||
Mean | ± | Mean | ± | Mean | ± | |||||||
0a | All | Mid | 2 | 2 | 3 | 7 | 2.54 | 0.04 | 3.11 | 0.04 | 29.48 | 0.19 |
0b | Half | Mid | 2 | 2 | 3 | 7 | 2.54 | 0.04 | 3.09 | 0.04 | 17.23 | 0.12 |
0c | All | Doc | 2 | 2 | 3 | 8 | 2.42 | 0.03 | 14.69 | 0.12 | 12.96 | 0.10 |
0d | Half | Doc | 2 | 2 | 3 | 8 | 1.24 | 0.02 | 7.88 | 0.09 | 7.94 | 0.07 |
1a | All | Mid | 3 | 2 | 3 | 7 | 0.06 | 0.00 | 4.31 | 0.05 | 25.62 | 0.18 |
1b | Half | Mid | 3 | 2 | 3 | 7 | 0.06 | 0.00 | 4.34 | 0.05 | 13.38 | 0.12 |
1c | All | Doc | 3 | 2 | 3 | 9 | 0.06 | 0.00 | 16.60 | 0.13 | 14.32 | 0.13 |
1d | Half | Doc | 3 | 2 | 3 | 9 | 0.07 | 0.00 | 10.39 | 0.09 | 11.19 | 0.09 |
2a | All | Mid | 2 | 3 | 3 | 7 | 2.53 | 0.04 | 0.01 | 0.00 | 29.47 | 0.19 |
2b | Half | Mid | 2 | 3 | 3 | 7 | 2.55 | 0.04 | 0.01 | 0.00 | 17.26 | 0.12 |
2c | All | Doc | 2 | 3 | 3 | 9 | 2.50 | 0.03 | 8.35 | 0.06 | 20.34 | 0.11 |
2d | Half | Doc | 2 | 3 | 3 | 9 | 1.42 | 0.02 | 5.22 | 0.06 | 12.74 | 0.08 |
3a | All | Mid | 3 | 3 | 3 | 8 | 0.07 | 0.00 | 0.01 | 0.00 | 31.65 | 0.19 |
3b | Half | Mid | 3 | 3 | 3 | 8 | 0.09 | 0.00 | 0.01 | 0.00 | 17.85 | 0.13 |
3c | All | Doc | 3 | 3 | 3 | 9 | 0.07 | 0.00 | 9.05 | 0.06 | 15.51 | 0.09 |
3d | Half | Doc | 3 | 3 | 3 | 9 | 0.03 | 0.00 | 5.29 | 0.06 | 10.80 | 0.07 |
4a | All | Mid | 2 | 2 | 4 | 8 | 6.22 | 0.06 | 7.67 | 0.06 | 26.90 | 0.17 |
4b | Half | Mid | 2 | 2 | 4 | 8 | 6.24 | 0.06 | 7.70 | 0.06 | 12.63 | 0.09 |
4c | All | Doc | 2 | 2 | 4 | 9 | 5.95 | 0.05 | 12.66 | 0.08 | 15.31 | 0.11 |
4d | Half | Doc | 2 | 2 | 4 | 9 | 4.46 | 0.05 | 7.03 | 0.07 | 10.36 | 0.08 |
5a | All | Mid | 3 | 2 | 4 | 8 | 1.46 | 0.02 | 10.78 | 0.07 | 20.60 | 0.14 |
5b | Half | Mid | 3 | 2 | 4 | 8 | 1.46 | 0.02 | 10.80 | 0.07 | 6.27 | 0.05 |
5c | All | Doc | 3 | 2 | 4 | 10 | 1.31 | 0.02 | 12.63 | 0.08 | 16.65 | 0.13 |
5d | Half | Doc | 3 | 2 | 4 | 10 | 0.46 | 0.01 | 9.40 | 0.07 | 8.80 | 0.08 |
6a | All | Mid | 2 | 3 | 4 | 8 | 6.26 | 0.06 | 1.18 | 0.02 | 27.00 | 0.17 |
6b | Half | Mid | 2 | 3 | 4 | 8 | 6.21 | 0.06 | 1.17 | 0.02 | 12.61 | 0.09 |
6c | All | Doc | 2 | 3 | 4 | 11 | 6.01 | 0.05 | 12.58 | 0.09 | 19.32 | 0.09 |
6d | Half | Doc | 2 | 3 | 4 | 10 | 3.95 | 0.04 | 4.92 | 0.05 | 9.99 | 0.07 |
7a | All | Mid | 3 | 3 | 4 | 10 | 1.30 | 0.02 | 1.59 | 0.02 | 30.62 | 0.17 |
7b | Half | Mid | 3 | 3 | 4 | 10 | 1.32 | 0.02 | 1.60 | 0.02 | 16.52 | 0.10 |
7c | All | Doc | 3 | 3 | 4 | 12 | 1.19 | 0.02 | 17.44 | 0.12 | 12.04 | 0.08 |
7d | Half | Doc | 3 | 3 | 4 | 11 | 0.46 | 0.01 | 7.33 | 0.07 | 7.78 | 0.05 |