Descriptive statistics: outcomes and covariates (2012–2017)
| Variables | N | n | % |
| ED outcomes | |||
| ED duration (>4 hours) | 1 038 751 | 293 102 | 28.22 |
| Hospital admission from ED | 1 039 251 | 600 368 | 57.77 |
| ED reattendance within 30 days | 1 038 808 | 212 050 | 20.41 |
| Patient characteristics | |||
| Age (median, IQR) | 1 039 251 | 83 | 9 |
| Age 75–80 | 1 039 251 | 302 234 | 29.08 |
| Age 80–85 | 1 039 251 | 305 512 | 29.40 |
| Age 85–90 | 1 039 251 | 250 855 | 24.14 |
| Age 90–95 | 1 039 251 | 138 961 | 13.37 |
| Age 95+ | 1 039 251 | 41 689 | 4.01 |
| Sex (=1 male) | 1 039 217 | 426 084 | 41.00 |
| IMD1—most deprived | 1 034 589 | 184 685 | 17.85 |
| IMD2 | 1 034 589 | 103 025 | 9.96 |
| IMD3 | 1 034 589 | 110 259 | 10.66 |
| IMD4 | 1 034 589 | 87 630 | 8.47 |
| IMD5 | 1 034 589 | 91 991 | 8.89 |
| IMD6 | 1 034 589 | 103 182 | 9.97 |
| IMD7 | 1 034 589 | 103 367 | 9.99 |
| IMD8 | 1 034 589 | 89 697 | 8.67 |
| IMD9 | 1 034 589 | 89 424 | 8.64 |
| IMD10—least deprived | 1 034 589 | 71 329 | 6.89 |
| Number of previous ED attendances (1-year window) (median, IQR) | 995 300 | 1 | 2 |
| Number of previous admissions (1-year window)=0 | 995 300 | 451 990 | 45.41 |
| Number of previous admissions (1-year window)=1 | 995 300 | 239 172 | 24.03 |
| Number of previous admissions (1-year window)=2 | 995 300 | 127 665 | 12.83 |
| Number of previous admissions (1-year window)=3+ | 995 300 | 176 473 | 17.73 |
| Care home (=1 yes) | 1 035 437 | 176 613 | 17.06 |
| Road travel distance (min) (LSOA to hospital) (median, IQR) | 1 034 814 | 10 | 10 |
| Death in ED or hospital | 1 039 251 | 52 705 | 5.07 |
| Pathway variables | |||
| Length NHS111 call (min)* (median, IQR) | 90 107 | 10.22 | 8.90 |
| Calls to NHS111 per day (>1)* | 90 107 | 5774 | 6.41 |
| Ambulance calls per day (>1)* | 552 940 | 24 595 | 4.45 |
| CH designation—less urgent | 552 940 | 264 694 | 47.87 |
| CH designation—urgent | 552 940 | 96 199 | 17.40 |
| CH designation—emergency | 552 940 | 187 033 | 33.83 |
| CH designation—life-threatening | 552 940 | 5014 | 0.91 |
| Time ambulance on scene (min)* (median, IQR) | 538 087 | 36.1 | 21.65 |
| Time from ambulance call to ED arrival (min)*† (median, IQR) | 552 940 | 71.15 | 38.3 |
| Site variables | |||
| Site size in 1000 (financial year) (median, IQR) | 1 039 251 | 11.92 | 6.92 |
| Number of attendances per consultant (financial year) (median, IQR) | 1 039 251 | 1388.50 | 967.03 |
| Occupancy rate per trust (quarterly) (median, IQR) | 1 039 251 | 84.45 | 7.29 |
| Time variables | |||
| Out of hours in ED (=1 yes) | 1 039 251 | 562 545 | 54.13 |
| Monday | 1 039 251 | 156 211 | 15.03 |
| Tuesday | 1 039 251 | 146 475 | 14.09 |
| Wednesday | 1 039 251 | 145 676 | 14.02 |
| Thursday | 1 039 251 | 145 886 | 14.04 |
| Friday | 1 039 251 | 148 965 | 14.33 |
| Saturday | 1 039 251 | 149 051 | 14.34 |
| Sunday | 1 039 251 | 146 987 | 14.14 |
| Bank holiday (=1 yes) | 1 039 251 | 29 706 | 2.86 |
| January | 1 039 251 | 91 581 | 8.81 |
| February | 1 039 251 | 81 889 | 7.88 |
| March | 1 039 251 | 89 752 | 8.64 |
| April | 1 039 251 | 84 017 | 8.08 |
| May | 1 039 251 | 87 292 | 8.40 |
| June | 1 039 251 | 83 788 | 8.06 |
| July | 1 039 251 | 85 871 | 8.26 |
| August | 1 039 251 | 85 107 | 8.19 |
| September | 1 039 251 | 82 874 | 7.97 |
| October | 1 039 251 | 86 338 | 8.31 |
| November | 1 039 251 | 84 768 | 8.16 |
| December | 1 039 251 | 95 974 | 9.23 |
*In the regressions, we assign 0 min to the rest of the observations.
†Ambulance on scene has missing values in the departure time.
%, percentage of observations with characteristic; CH, call handler; IMD, Index of Multiple Deprivation; LSOA, Lower Super Output Area; n, observations with characteristic; N, total observations.