The effect of base station contact on ambulance destination

Concern has been raised that a single medical control base station serving a metropolitan area may preferentially divert ambulance patients to the base station hospital. Such concern may discourage the development of regional medical control systems. During the first six months of 1988, a retrospective cross-sectional analysis was made of all advanced life support (ALS) ambulance transports and all contacts to the single base station, known as Medical Resource Hospital (MRH). Destinations of all ALS ambulance calls dispatched through the county's 911 dispatch center were analyzed to determine whether the destinations were affected by MRH contact. There were 12,396 transports to 17 area hospitals with 1,272 (10.3%) of these requiring MRH contact. We hypothesized that if MRH contact did not affect destination, the proportion of all non-MRH ALS ambulance patients received by each hospital from the 911-dispatched group would equal the proportion of patients received by each hospital after MRH contact. Five hospitals received a statistically significant (P < .003) different percentage of MRH contact patients than their proportion of 911-dispatched patients would have predicted. The three that received more were community hospitals in outlying areas. The remaining two were a large referral hospital and a smaller community hospital located in the urban area. The MRH hospital did not have a significantly different percentage of 911-dispatched patients after MRH contact. Similarly, destinations of specific ALS ambulances (two serving in the MRH ambulance catchment area and four in distant catchment areas) were evaluated. MRH did not receive a statistically higher proportion of ambulance patients from either group after MRH contact than the 911 dispatch proportion would have predicted. We found no evidence of preferential diversion of patients to the base station hospital.