The 911 emergency telephone number: impact on emergency medical systems access in a metropolitan area.

The telephone number 911 is designated for public use in requesting emergency assistance. It is thought to reduce response time by reducing the interval between the decision to call for assistance and the notification of an agency that can dispatch the appropriate services. The experience of the Twin Cities metropolitan area of Minneapolis-St. Paul provides a unique opportunity to examine this assumption. Prior to the introduction of the 911 emergency telephone number on December 1, 1982, the area was serviced by over 100 different seven-digit emergency telephone numbers. Before the introduction of 911, 347 callers who activated the emergency medical services (EMS) system were interviewed, and after 911 was introduced, 305 callers were interviewed. Activation of the EMS system by making one call in less than 1 minute was achieved by 219 of 347 callers (63%) in the pre-911 phase and by 251 of 305 callers (82%) in the post-911 phase (P less than 0.001). Compliance (use of an appropriate emergency number for the first call) was demonstrated by 139 of 347 callers (40%) in the pre-911 phase, and 225 of 305 callers (74%) in the post-911 phase (P less than 0.001). Rapid activation of the EMS system was rarely achieved by calling a hospital or physician first. Overall, 911 was found to be a more efficient means of activating the EMS system.