Mobile intensive care units. An evaluation of effectiveness.

Implementation of mobile intensive care units in four suburban communities permitted a retrospective evaluation of their impact on patient outcome. Data on 1,796 cases of myocardial infarction were obtained from medical reords and death certificates of patients arriving at four hospitals during a 65-month period. There were statistically significant reductions in mortality rates in two communities (41.1% to 23.9% and 37.6% to 27.0%) after the service began. A reduction in one community (34.5% to 22.0%) was not statistically significant, and the fourth community showed an increase in the mortality rate (31.1% to 44.0%). Analysis of plausible rival hypotheses permitted most of these to be ruled out as causes for the observed reduction in mortality.