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Is Prehospital Advanced Life Support Harmful?

TO THE EDITOR: We read Sasson and Haukoos' editorial (1) with interest. In an ideal world, prehospital care would be consistent with evidence from randomized clinical trials that assess the efficacy of each potentially available treatment method for each patient subgroup. Large-scale observational studies like ours (2) would then assess the effectiveness of these treatments as applied in the field, like similar studies of treatment alternatives in other, better-researched fields of medicine. Because no such evidence base exists for prehospital emergency care, our observational findings assume greater importance. Despite their limitations, they provide powerful evidence that the package of practices and services associated with advanced life support (ALS) is associated with worse outcomes than that of basic life support (BLS) in several of the most common and serious conditions that require emergency transportation for elderly patients. In a randomized clinical trial, outcomes can be compared without knowing details of the clinical procedures in each group, the patients' intermediate health status, or the specific biological mechanisms involved. To compare average outcomes of patients treated by ALS or BLS providers, it is similarly not necessary to know the details of the interventions, the patients' intermediate health status, or the mechanisms causing differences in outcomes. In fact, adjusting for variables influenced by the ambulance type, such as specific clinical interventions or scene and transport times, is inappropriate for estimating a treatment effect. Our results establish that the bundle of services associated with ALS on average leads to worse outcomes than that associated with BLS, with 1 contrary case highlighted by Sasson and Haukoos (acute myocardial infarction, determined by propensity score analysis). The important next step is to identify which elements of the ALS bundle of services, if any, are beneficial for which patients and under which circumstances and, conversely, which are most harmfulthat is, which would produce the negative average effects that we estimated for most diagnoses and end points. Sasson and Haukoos' assertion that ALS may not be better than BLS but cannot be worse is at odds with our findings. The Canadian OPALS (Ontario Prehospital Advanced Life Support) study that they cite to support equivalence between ALS and BLS found worse outcomes with ALS for trauma patients with low Glasgow Coma Scale scores. Moreover, extrapolating findings from a carefully monitored, controlled trial in Canada to the average, unmonitored emergency medical service in the United States is problematic. Despite our differences, we agree with Sasson and Haukoos that the evidence base for prehospital care is sorely lacking. It is crucial that our system for this care be consistent with scientific evidence.