The findings are based on 10 years of data in three emergency departments. including a minor injuries unit, in Sheffield, a large city in northern England.
The data, which record the time taken for every episode of care, from booking in until discharge from the emergency medicine department, were collected every year from 1993 to 2003 for four months from April to July.
Patients were categorised into "minors" - those who arrived under their own steam, and were subsequently discharged - and "majors" - those who arrived by emergency ambulance and were admitted to hospital.
Over the 10 years, emergency care attendances increased by 969 or 1.3% year on year, and the proportion of people admitted to hospital increased over 7%.
The numbers of young patients between 16 and 29 fell 10%, while those aged over 80 rose from 6.2% to 10.4%.
The proportion of patients arriving by ambulance also increased from around 23% to a peak of 32% in 2002. Similarly, the proportion of "minor" emergencies fell by around 10%.
Average waiting times doubled, and average treatment times also increased, especially for major cases. These almost quadrupled from 55 minutes in 1993 to 205 minutes in 2003, despite increases in staffing levels.
Overall, the percentage of patients seeing a healthcare professional within an hour of arrival fell by around 20% over the 10 years.
The authors point out that the results suggest an additional 9000 patients a year are being admitted to hospital in Sheffield, at a time when the number of beds has fallen.
They suggest that changes in the way illness is dealt with in the community are putting undue pressure on emergency care services.
Journal
Emergency Medicine Journal