title: Quality of CPR: An important effect modifier in cardiac arrest clinical outcomes and intervention effectiveness trials.
abstract: OBJECTIVE
  To determine if the quality of CPR had a significant interaction with the primary study intervention in the NIH PRIMED trial.
  
  
  METHODS
  The public access database from the NIH PRIMED trial was accessed to determine if there was an interaction between quality of CPR performance, intervention, and outcome (survival to hospital discharge with modified Rankin Score (mRS) ≤ 3).
  
  
  METHODS
  Multi-centered prehospital care systems across North America.
  
  
  METHODS
  Of 8719 adult patients enrolled, CPR quality was electronically recorded for compression rate, depth, and fraction in 6199 (71.1%), 3750 (43.0%) and 6204 (71.2%) subjects, respectively. "Acceptable" quality CPR was defined prospectively as simultaneous provision of a compression rate of 100/min (± 20%), depth of 5 cm (± 20%) and fraction of > 50%. Significant interaction was considered as p < 0.05.
  
  
  METHODS
  Standard CPR with an activated versus sham (inactivated) ITD.
  
  
  RESULTS
  Overall, 848 and 827 patients, respectively, in the active and sham-ITD groups had "acceptable" CPR quality performed (n = 1675). There was a significant interaction between the active and sham-ITD and compression rate, depth and fraction as well as their combinations. The strongest interaction was seen with all three parameters combined (unadjusted and adjusted interaction p-value, < 0.001). For all presenting rhythms, when "acceptable" quality of CPR was performed, use of an active-ITD increased survival to hospital discharge with mRS ≤ 3 compared to sham (61/848 [7.2%] versus 34/827 [4.1%], respectively; p = 0.006). The opposite was true for patients that did not receive "acceptable" quality of CPR. In those patients, use of an active - ITD led to significantly worse survival to hospital discharge with mRS ≤ 3 compared to sham (34/1012 [3.4%] versus 62/1061 [5.8%], p = 0.007).
  
  
  CONCLUSIONS
  There was a statistically significant interaction between the quality of CPR provided, intervention, and survival to hospital discharge with mRS ≤ 3 in the NIH PRIMED trial. Quality of CPR delivered can be an underestimated effect modifier in CPR clinical trials.
authors.affiliation: University of Minnesota, 420 Delaware Street SE, Minneapolis, MN 55455, United States. Electronic address: yanno001@umn.edu.
authors.forename: Demetris
authors.initials: D
authors.lastname: Yannopoulos
authors.affiliation: Medical College of Wisconsin, 9200 West Wisconsin, Milwaukee, WI 53226, United States.
authors.forename: Tom P
authors.initials: TP
authors.lastname: Aufderheide
authors.affiliation: University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, United States.
authors.forename: Benjamin S
authors.initials: BS
authors.lastname: Abella
authors.affiliation: University of Minnesota, 420 Delaware Street SE, Minneapolis, MN 55455, United States.
authors.forename: Sue
authors.initials: S
authors.lastname: Duval
authors.affiliation: University of Minnesota, 420 Delaware Street SE, Minneapolis, MN 55455, United States.
authors.forename: Ralph J
authors.initials: RJ
authors.lastname: Frascone
authors.affiliation: University of Oklahoma School of Community Medicine, 1145 S. Utica Ave, 6th Floor, Tulsa, OK 74104, United States.
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Goodloe
authors.affiliation: Hennepin County Medical Center, 701 Park Avenue, Minneapolis, MN 55415, United States.
authors.forename: Brian D
authors.initials: BD
authors.lastname: Mahoney
authors.affiliation: University of Pennsylvania and Children's Hospital of Philadelphia, 34th Street and Civic Center Boulevard, Philadelphia, PA 19104, United States.
authors.forename: Vinay M
authors.initials: VM
authors.lastname: Nadkarni
authors.affiliation: Johns Hopkins Hospital, 600 North Wolfe Street, Baltimore, MD 21287, United States.
authors.forename: Henry R
authors.initials: HR
authors.lastname: Halperin
authors.affiliation: University of Virginia, P.O. Box 800699, Charlottesville, VA 22908, United States.
authors.forename: Robert
authors.initials: R
authors.lastname: O'Connor
authors.affiliation: University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, United States.
authors.forename: Ahamed H
authors.initials: AH
authors.lastname: Idris
authors.affiliation: Medical College of Wisconsin, 9200 West Wisconsin, Milwaukee, WI 53226, United States.
authors.forename: Lance B
authors.initials: LB
authors.lastname: Becker
authors.affiliation: University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-8579, United States.
authors.forename: Paul E
authors.initials: PE
authors.lastname: Pepe
mesh_terms: D016887:Cardiopulmonary Resuscitation / Q000592:standards*; D002986:Clinical Trials as Topic; D004632:Emergency Medical Services / Q000592:standards*; D006801:Humans; D009656:North America; D058687:Out-of-Hospital Cardiac Arrest / Q000628:therapy*
keywords: Cardiac arrest; Cardiopulmonary resuscitation (CPR); Chest compressions; Effect modification; Impedance threshold device; Quality of CPR