OPALS Studies

The landmark OPALS Study for Adults, is the largest prehospital study yet conducted worldwide with some 17 cities and 18,000 cases included overall. The study was designed to evaluate the impact of prehospital interventions on four major groups of adult patients: 1) cardiac arrest, 2) major trauma, 3) respiratory arrest, and 4) chest pain in 17 Ontario cities. The cardiac arrest component of the study was comprised of three sequential phases.1 Phase I, 36 months of baseline basic life support with defibrillation (BLS-D) EMS, demonstrated the importance of bystander CPR in patient survival in 4,690 patients.2 Phase II demonstrated, in an additional 1,641 patients, that the inexpensive optimization of an existing defibrillation program could lead to significant improvements in survival.3 Phase III, 36 months with a full ALS paramedic program, enrolled an additional 4,247 patients and showed no incremental benefit in survival from ALS but was the first study to quantify the importance of the links in the cardiac arrest chain of survival.4

The major trauma component enrolled 2,884 patients with ISS > 12 during two 36-month periods before and after the introduction of ALS programs in the OPALS Study cities and found no benefit from ALS interventions publication is expected in 2006.5,6 The respiratory distress aspect of the study enrolled 8,138 patients presenting with shortness of breath secondary to a variety of conditions including congestive heart failure, chronic obstructive pulmonary disease, asthma, and pneumonia.5 This study demonstrated an important decrease in patient mortality and improvement in numerous secondary outcomes in the ALS phase the paper will also be published in 2006.7 The chest pain component has enrolled 13,000 patients and preliminary results indicate a very important reduction in mortality during the ALS phase.8 The OPALS investigators have also been very active in unique work to evaluate the quality of life of cardiac arrest survivors as well as other important findings.9-12

  1. Stiell IG, Spaite DW, Wells GA, et al. The OPALS Study: Rationale and Methodology for Cardiac Arrest Patients. Ann Emerg Med 1998; 32:180-190.
  2. Stiell IG, Wells GA, De Maio VJ, Spaite DW, Field BJ, Munkley DP et al. Modifiable factors associated with improved cardiac arrest survival in a multicenter basic life support/defibrillation system: OPALS Study Phase I Results. Ann Emerg Med 1999; 33:44-50.
  3. Stiell IG, Wells GA, Field BJ, Spaite DW, De Maio VJ, Ward RE et al. Improved out-of-hospital cardiac arrest survival through the inexpensive optimization of an existing defibrillation program, OPALS Study Phase II. JAMA 1999; 281:1175-1181.
  4. Stiell IG, Wells GA, De Maio VJ, Nesbitt L et al. Advanced Cardiac Life Support in Out-of-Hospital Cardiac Arrest. N Engl J Med 2004; 351:647-656.
  5. Stiell IG, Wells GA, Spaite DW, Nichol G, O'Brien B, Munkley DP et al. The Ontario Prehospital Advanced Life Support (OPALS) Study Part II: Rationale and methodology for trauma and respiratory distress patients. Ann Emerg Med 1999; 34:256-262.
  6. Stiell IG, Nesbitt L, Pickett W, Brisson D et al. OPALS Major Trauma Study: impact of advanced life support on survival and morbidity. Acad Emerg Med 2005; 12(5):7.
  7. Stiell IG, Wells GA, De Maio VJ et al. Multicenter trial to evaluate the impact of ALS on out-of-hospital respiratory distress patients. Acad Emerg Med 2002; 9(5):357.
  8. Stiell IG, Nesbitt L, Wells GA et al. Multicenter controlled trial to evaluate the impact of ALS on out-of-hospital chest pain patients. Acad Emerg Med 2003; 10(5):501.
  9. Stiell IG, Nichol G, Wells GA De Maio VJ et al. Quality of life is better for cardiac arrest survivors who received citizen CPR. Circulation 2003; 108:1939-1944.
  10. De Maio VJ, Stiell IG, Wells GA, Spaite DW, for the OPALS Study Group. Cardiac arrest witnessed by emergency services personnel: descriptive epidemiology, prodromal symptoms, and predictors of survival. Ann Emerg Med 2000; 35:138-146.
  11. De Maio VJ, Stiell IG et al. CPR-only survivors of out-of-hospital cardiac arrest: implications for care and research methodology. Ann Emerg Med 2001; 37:602-608.
  12. De Maio VJ, Stiell IG, Wells GA et al. Optimal defibrillation response intervals for maximum out-of-hospital cardiac arrest survival. Ann Emerg Med 2003; 42(2):242-250.
  13. Donoghue AJ, Nadkarni V, Berg RA, Osmond MH, Wells GA et al. Out-of-hospital pediatric cardiac arrest: review of knowledge. Ann Emerg Med 2005; 46:512-522.

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Protocol Summary:



This multi-phase before-after study (see OPALS Research Protocol) is being conducted in multiple communities in 11 base hospital regions and has three distinct phases involving a total of at least 10,000 cardiac arrest patients, 6,000 major trauma patients and 8,000 respiratory distress patients.

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Study Documents for Download:

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Ottawa Team:

Cathy Clement
Senior Research Program Manager / Associate

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