Need for Outcome Measurement
Why are such large sums of money spent on a system with seemingly little evidence of efficacy?27 One reason is that efficacy information is difficult to define and obtain. Part of the problem lies in the uncertainty of how to measure patient outcome. An obvious outcome measure is mortality or lives saved. While seemingly easy to define, there is uncertainty over determining when a “save” occurs. Is it a “save” if a patient requiring CPR is admitted to the intensive care unit but dies after three days? Is it a “save” if that same patient dies in six months but was able to spend five of those months at home with his family?
Mortality is often not a good measure of patient impact because it is an infrequent outcome in many disorders. Evaluation of an infrequent outcome requires either large numbers of patients, long periods of time, or sometimes both. EMS currently lacks the resources for these large research efforts. Disability, relief of suffering, utilization of health services, and costs may be better measures of outcome but are often even more complex to define and obtain. For example, attempting to answer a question such as, “what is the relative benefit of transporting a patient with a femur fracture to the hospital in the back of an ambulance with a leg splint versus by taxicab with no treatment?” can be challenging as one begins to define “benefit.”
Accurately measuring outcome is made more challenging by the fact that the patient is delivered by EMS directly to a more comprehensive part of the health care system. Definitive care is seldom delivered in the field, but significant supportive care may take place there. Attribution of ultimate patient outcome to prehospital events is therefore confounded by the impact of interventions received by the patient later in the continuum of care. Measuring the impact of EMS patient care is further complicated by the concentration of specialized medical services such as major trauma care and tertiary pediatrics in a few experienced hospitals. When treating patients with problems such as major trauma, efficient transport to the optimal facility may be the most important prehospital intervention.28