Table 1

Association of day and time of attendance with risk-adjusted mortality within 30 days of admission

	Volume of admitted patients		Crude mortality rate	Model 1 Standard risk adjustment		Model 2 Standard risk adjustment plus mode of arrival		Model 3 Standard risk adjustment (mode of arrival: ambulance)		Model 4 Standard risk adjustment (mode of arrival: non-ambulance)
	Total	Arrived by ambulance	(%)	OR	95% CI	OR	95% CI	OR	95% CI	OR	95% CI
Day and time
Wednesday day	273 739	157 675	3.66	Ref.	–	Ref.	–	Ref.	–	Ref.	–
Wednesday night	158 297	106 248	3.48	1.055	1.016 to 1.096	0.988	0.951 to 1.025	0.980	0.943 to 1.020	1.093	0.952 to 1.255
Thursday day	277 620	160 146	3.75	1.028	0.996 to 1.060	1.027	0.996 to 1.060	1.030	0.997 to 1.065	1.015	0.920 to 1.121
Thursday night	159 197	107 511	3.46	1.052	1.013 to 1.092	0.986	0.950 to 1.024	0.977	0.940 to 1.016	1.117	0.975 to 1.281
Friday day	278 570	159 339	3.71	1.001	0.970 to 1.033	1.007	0.976 to 1.039	1.006	0.973 to 1.041	1.015	0.921 to 1.120
Friday night	165 502	112 742	3.28	1.026	0.989 to 1.066	0.962	0.927 to 0.999	0.958	0.921 to 0.996	1.006	0.874 to 1.158
Saturday day	251 464	153 602	4.00	1.058	1.025 to 1.092	1.031	0.999 to 1.064	1.028	0.995 to 1.063	1.097	0.988 to 1.219
Saturday night	164 312	113 400	3.32	1.073	1.033 to 1.114	0.997	0.960 to 1.035	0.992	0.954 to 1.032	1.075	0.927 to 1.246
Sunday day	256 531	154 123	4.12	1.089	1.056 to 1.124	1.061	1.028 to 1.095	1.055	1.020 to 1.090	1.186	1.070 to 1.314
Sunday night	155 299	105 371	3.59	1.096	1.055 to 1.137	1.019	0.981 to 1.058	1.011	0.972 to 1.051	1.147	0.991 to 1.326
Monday day	294 526	164 155	3.72	1.010	0.979 to 1.042	1.017	0.986 to 1.049	1.014	0.981 to 1.048	1.056	0.960 to 1.161
Monday night	160 510	106 782	3.43	1.008	0.971 to 1.046	0.947	0.912 to 0.983	0.940	0.904 to 0.977	1.052	0.918 to 1.205
Tuesday day	275 470	157 148	3.68	1.004	0.973 to 1.036	1.007	0.975 to 1.039	1.008	0.975 to 1.043	0.994	0.901 to 1.097
Tuesday night	156 909	105 004	3.41	1.027	0.988 to 1.066	0.964	0.929 to 1.002	0.971	0.933 to 1.010	0.871	0.753 to 1.006
Average	216 282	133 089	3.66
Mode of arrival
Ambulance	1 863 246		5.46			Ref.	–
Non-ambulance	1 152 854		0.78			0.339	0.330 to 0.348
Unknown	11 846		1.20			0.456	0.380 to 0.548
N	3 027 946			3 027 946		3 027 946		1 863 246		1 152 854
C-statistic				0.907		0.911		0.877		0.951

Standard risk adjustment includes controls for age, gender, ethnicity, primary diagnosis, Elixhauser conditions, admission source, deprivation quintile, month and admitting hospital. Daytime defined as 07:00 to 18:59, night-time defined as 19:00 to 06:59 the following day. Marginal effects reported in online supplementary appendix table A3.