Table 2

Definitions for derived variables for ED and hospital workload and staffing factors used in this analysis

VariableVariable typeDefinition
IMD scoreCategoricalQuintile 1 (least deprived)—IMD score <24.94
Quintile 2—IMD score 24.94–34.75
Quintile 3—IMD score 34.76–41.05
Quintile 4—IMD score 41.06–48.33
Quintile 5 (most deprived)—IMD score>48.33
ED bed occupancy rateContinuousRatio of patients in the department in any given hour during the day, to the number of adults beds in the ED (see table 1)
Arrival intensityContinuousRaw number of patients arriving in the department during each hour of the day
Ambulance arrival intensityContinuousRatio of patients arriving in the department by ambulance in any given hour, to the total number of patients arriving in that hour
‘Left without being treated’ContinuousNumber of patients who left without treatment in any given hour as a proportion of all those leaving within the same hour
Late dischargeBinaryPositive score (1) applied to each patient who left the department between 230 and 240 min of initial attendance time. This measure was derived to investigate the impact of the 4-hour quality indicator on admission
Inpatient bed occupancy rateContinuousProportion of general and acute medical beds occupied within each hospital, each day of the month. Figures are reported at 9:00 every day
Consultant on dutyBinaryPositive score (1) applied to each record for which a consultant was on duty at the time of arrival in the ED
  • ED, emergency department; IMD, Index of Multiple Deprivation.