Optimization for Locating Emergency Medical Service Facilities: A Case Study for Health Planning from China

Figures & data

Figure 1 Population density (A), road network (B) and distribution of network hospitals (C) in Chengdu, 2017.

Table 1 Parameter Settings in GA

Parameter	Value
Population size	1000
Number of genes	463
Probability of crossover	0.8
Probability of mutation	0.1
Number of best individuals survived at each generation	5% of population size (50)
Number of iterations without improvement before stop	1500

Table 2 Access to EMS Before and After Facility Upgrading

	Current Status		After Facility Upgrading
	Median Shortest Travel Time (IQR)	Population Coverage in 15 Min	Median Shortest Travel Time (IQR)	Population Coverage in 15 Min
Total	6.45 (10.65)	78.27%	5.51 (7.17)	90.05%
District
Chenghua	2.55 (1.82)	100.00%	2.55 (1.82)	100.00%
Jinniu	3.26 (3.39)	100.00%	3.26 (3.39)	100.00%
Jinjiang	2.26 (2.27)	100.00%	2.26 (2.27)	100.00%
Qingyang	2.10 (1.47)	100.00%	2.10 (1.47)	100.00%
Wuhou	2.46 (1.78)	100.00%	2.46 (1.78)	100.00%
Pidu	6.65 (5.87)	96.80%	6.28 (4.74)	99.33%
Xindu	7.90 (5.96)	94.86%	7.78 (5.51)	97.81%
Longquan	5.74 (6.18)	93.18%	4.95 (5.50)	96.21%
Shuangliu	7.47 (5.85)	92.63%	6.93 (5.74)	95.06%
Xinjin	10.37 (5.48)	85.46%	10.28 (5.09)	88.05%
Wenjiang	8.82 (7.64)	82.95%	7.29 (4.29)	98.83%
Qingbaijiang	10.42 (6.40)	76.85%	8.02 (5.31)	92.39%
Dujiangyan	10.81 (14.27)	64.46%	8.27 (5.68)	92.00%
Chongzhou	12.57 (9.59)	61.17%	8.90 (7.26)	88.01%
Pujiang	13.69 (11.87)	58.34%	10.19 (7.91)	80.96%
Dayi	13.78 (9.88)	56.39%	10.12 (6.83)	81.85%
Pengzhou	13.87 (10.54)	55.34%	8.17 (6.45)	88.59%
Qionglai	15.85 (18.45)	47.34%	10.30 (11.43)	70.09%
Jintang	18.90 (16.30)	37.26%	11.32 (9.78)	70.21%
Jianyang	34.35 (20.48)	10.94%	15.93 (14.37)	46.73%

Abbreviation: IQR, interquartile range.

Figure 2 Access (shortest travel time) to network hospitals before (A) and after facility upgrading (B).

Figure 3 Distribution of current and newly upgraded network hospitals in Chengdu. Numbers denoted the upgrading order of each facility.

Table 3 Summary Results of Three Sensitivity Analyses

Objective	Strategy	Candidate Set	Result
Objective 1: Achieving 90% coverage of EMS within 15 min	Reselecting all network hospitals	Qualified hospitals and township health centers	81 Facilities were selected
		558 facilities in total	90.01% coverage within 15 min
Objective 2: Achieving 90% coverage of EMS within 15 min	Upgrading to network hospitals	Hospitals plus qualified township health centers	54 New facilities were upgraded
		753 facilities in total	90.13% coverage within 15 min
Objective 3: Achieving 90% coverage of EMS within 12 min	Reselecting all network hospitals	All healthcare facilities in Chengdu	206 Facilities were selected
		1173 facilities in total	90.02% coverage within 12 min