Emergency call work-load, deprivation and population density: an investigation into ambulance services across England.

Demand for emergency ambulance services has risen steeply over the recent years. This study examined differences in work-load of ambulance services across England and investigated factors linked to high demand. The number of emergency calls received by each ambulance service in 1997 and 2002 and population and area data were used to calculate call rates and population density for each of 27 service areas. Deprivation score and proportion of the population under age 15 and over age 65 were calculated for each service area. There was wide variation in emergency call rates across England, with London having the highest rate both in 1997 (125.6 calls per 1000 persons) and in 2002 (140.1 per 1000). Statistically significant positive associations were observed between call rates and deprivation (1997, r = 0.49; 2002, r = 0.53) and between call rates and population density (1997, r = 0.70; 2002, r = 0.68). Following multivariable regression, the effect of deprivation score was consistently weaker, but the effect of population density was virtually unchanged. We conclude that areas with higher population density have higher call rates, which is not explained by deprivation. Deprivation is associated with higher usage, but its effect is partly due to population density. There is no evidence that these relationships are confounded by age.