Outcomes of Basic Versus Advanced Life Support for Out-of-Hospital Medical Emergencies

Background: Most Medicare patients seeking emergency medical transport are treated by ambulance providers trained in advanced life support (ALS). Evidence supporting the superiority of ALS over basic life support (BLS) is limited, but some studies suggest ALS may harm patients. Objective: To compare outcomes after ALS and BLS in out-of-hospital medical emergencies. Design: Observational study with adjustment for propensity score weights and instrumental variable analyses based on county-level variations in ALS use. Setting: Traditional Medicare. Patients: 20% random sample of Medicare beneficiaries from nonrural counties between 2006 and 2011 with major trauma, stroke, acute myocardial infarction (AMI), or respiratory failure. Measurements: Neurologic functioning and survival to 30 days, 90 days, 1 year, and 2 years. Results: Except in cases of AMI, patients showed superior unadjusted outcomes with BLS despite being older and having more comorbidities. In propensity score analyses, survival to 90 days among patients with trauma, stroke, and respiratory failure was higher with BLS than ALS (6.1 percentage points [95% CI, 5.4 to 6.8 percentage points] for trauma; 7.0 percentage points [CI, 6.2 to 7.7 percentage points] for stroke; and 3.7 percentage points [CI, 2.5 to 4.8 percentage points] for respiratory failure). Patients with AMI did not exhibit differences in survival at 30 days but had better survival at 90 days with ALS (1.0 percentage point [CI, 0.1 to 1.9 percentage points]). Neurologic functioning favored BLS for all diagnoses. Results from instrumental variable analyses were broadly consistent with propensity score analyses for trauma and stroke, showed no survival differences between BLS and ALS for respiratory failure, and showed better survival at all time points with BLS than ALS for patients with AMI. Limitation: Only Medicare beneficiaries from nonrural counties were studied. Conclusion: Advanced life support is associated with substantially higher mortality for several acute medical emergencies than BLS.