Table 4.

Multivariate Poisson regression analysis of difficult-to-transfer cases in all patients

	Risk Ratio	95% confidence interval			P value
Year
2018	Reference
2019	0.93	0.90	−	0.95	< 0.001
2020	1.24	1.21	−	1.27	< 0.001
Month
June	Reference
January	1.93	1.84	−	2.02	< 0.001
February	1.85	1.76	−	1.94	< 0.001
March	1.49	1.41	−	1.57	< 0.001
April	1.59	1.51	−	1.67	< 0.001
May	1.39	1.32	−	1.47	< 0.001
July	1.14	1.08	−	1.20	< 0.001
August	1.41	1.34	−	1.49	< 0.001
September	1.20	1.14	−	1.27	< 0.001
October	1.12	1.06	−	1.18	< 0.001
November	1.28	1.21	−	1.35	< 0.001
December	1.52	1.45	−	1.60	< 0.001
Time of transportation
9 am to 10 am	Reference
0 am to 1 am	6.44	5.91	−	7.02	< 0.001
1 am to 2 am	7.42	6.80	−	8.08	< 0.001
2 am to 3 am	7.95	7.29	−	8.67	< 0.001
3 am to 4 am	7.66	7.02	−	8.37	< 0.001
4 am to 5 am	7.61	6.96	−	8.31	< 0.001
5 am to 6 am	6.80	6.21	−	7.44	< 0.001
6 am to 7 am	5.49	5.01	−	6.00	< 0.001
7 am to 8 am	3.98	3.63	−	4.36	< 0.001
8 am to 9 am	2.16	1.97	−	2.38	< 0.001
10 am to 11 am	1.25	1.13	−	1.38	< 0.001
11 am to 12 pm	1.58	1.44	−	1.75	< 0.001
12 pm to 1 pm	1.92	1.75	−	2.11	< 0.001
1 pm to 2 pm	2.18	1.98	−	2.39	< 0.001
2 pm to 3 pm	2.21	2.01	−	2.42	< 0.001
3 pm to 4 pm	2.41	2.19	−	2.64	< 0.001
4 pm to 5 pm	2.41	2.19	−	2.64	< 0.001
5 pm to 6 pm	3.08	2.82	−	3.37	< 0.001
6 pm to 7 pm	3.85	3.54	−	4.20	< 0.001
7 pm to 8 pm	4.48	4.12	−	4.88	< 0.001
8 pm to 9 pm	4.81	4.42	−	5.23	< 0.001
9 pm to 10 pm	4.86	4.46	−	5.29	< 0.001
10 pm to 11 pm	5.25	4.82	−	5.72	< 0.001
11 pm to 0 am	5.76	5.29	−	6.28	< 0.001
Day of week
Friday	Reference
Monday	1.11	1.07	−	1.15	< 0.001
Tuesday	1.08	1.04	−	1.12	< 0.001
Wednesday	1.09	1.05	−	1.13	< 0.001
Thursday	1.06	1.02	−	1.10	0.004
Saturday	1.26	1.21	−	1.30	< 0.001
Sunday	1.38	1.34	−	1.43	< 0.001
Adults, ≥ 15 years	Reference
Children	0.35	0.33	−	0.37	< 0.001
Suspected COVID-19	2.50	2.27	−	2.75	< 0.001