Table 2.

The average degree and betweenness centrality at different levels of medical institutions

		n	2017	n	2018	n	2019	n	2020	n	2021	n	2022	n	2023	Z	P trend
Out-degree
	Tertiary hospital***	1	8.9530	1	7.8105	1	9.1935	1	3.9194	1	15.6025	1	18.5905	1	20.0847	3.7957	< 0.001
	Secondary hospitals	1	0.0041	3	0.0488	3	0.0923	3	0.1162	3	1.7181	4	4.2007	4	4.1399	8.1591	< 0.001
	Primary care facilities	53	0.0700	55	0.0631	59	0.0902	57	0.0972	58	0.1133	54	0.0898	56	0.0827	2.4323	< 0.05
	Public PCFs	26	0.1238	28	0.1136	30	0.1486	30	0.1593	32	0.1864	31	0.1449	33	0.1403	-2.4906	< 0.05
	Private PCFs	27	0.0154	27	0.0109	29	0.0298	27	0.0282	26	0.0233	23	0.0131	23	0.0000	5.1768	< 0.001
In-degree
	Tertiary hospital***	1	2.9091	1	3.3669	1	4.4879	1	4.2042	1	5.1339	1	3.5805	1	3.3361	0.8577	0.391
	Secondary hospitals	1	0.4804	3	0.1192	3	0.2787	3	0.4458	3	0.4795	4	0.4526	4	0.3236	3.2243	< 0.01
	Primary care facilities	53	0.1851	55	0.1349	59	0.1605	57	0.0749	58	0.3579	54	0.5671	56	0.6544	3.9233	< 0.001
	Public PCFs	26	0.2345	28	0.1843	30	0.2147	30	0.0982	32	0.6061	31	0.8689	33	0.9945	3.1933	< 0.01
	Private PCFs	27	0.1348	27	0.0838	29	0.1044	27	0.0490	26	0.0524	23	0.1472	23	0.1664	5.1856	< 0.001
Betweenness
	Tertiary hospital***	1	0.4563	1	0.3061	1	0.3930	1	0.2765	1	0.2003	1	0.3586	1	0.2829	-2.6522	< 0.01
	Secondary hospitals	1	0.0122	3	0.0005	3	0.0146	3	0.0250	3	0.0227	4	0.0402	4	0.0202	4.1038	< 0.001
	Primary care facilities	53	0.0005	55	0.0002	59	0.0011	57	0.0015	58	0.0007	54	0.0010	56	0.0006	1.8341	0.066
	Public PCFs	26	0.0007	28	0.0002	30	0.0018	30	0.0019	32	0.0009	31	0.0013	33	0.0010	-2.6236	< 0.01
	Private PCFs	27	0.0003	27	0.0002	29	0.0004	27	0.0009	26	0.0004	23	0.0005	23	0.0000	0.1803	0.8569

*** Kruskal-Wallis test comparing centrality at different levels of hospitals. P < 0.001