Table 2.

Case Ascertainment Criteria and Sources

	Case ascertainment criteria
Source	Time	Geograph y	Disease Attributio n	Witnessed or Unwitness ed	Age	SCA include d	Sources for case ascertainment
Gillum, RF(13)	Not specified	Out-of- hospital or in the emergenc y room	Ischemic heart disease	Not specified	≥25 years old	no	1) National Center for Health Statistics (NCHS) data from the 40 states that reported data 2) US standard certificate of death, item 7c*
Escobedo, et al.(14)	≤ 1 hr of onset of cardio- vascular symptoms	Not specified	Coronary heart disease	Not specified	≥25 years old	no	1) 1986 National Mortality Followback Survey (did not include data from Oregon or patients < 25 years old)† 2) 1980 US Bureau of the Census data 3) Death certificates (death considered to have resulted from coronary heart disease if death certificate listed rubrics 410 through 414 International Classification of Diseases, 9th revision) 4) Additional information obtained through questionnaire/interview of person identified as the informant on death certificate (89% of informants responded)
Zheng, et al.(17)	≤1 hour of symptoms	Out-of- hospital or in the emergenc y room or “dead on arrival” with underlying cause of death reported as cardiac disease	Cardiac disease death	Not specified	≥ 35 years old	no	1) NCHS data 2) Death certificates (death considered to have resulted from cardiac disease if underlying cause of death classified using ICD-9 codes 390–398, 402, or 404–429)
Cobb, et al.(15)	Not specified	Out-of- hospital	Cardiac cause	Witnessed or unwitnesse d	≥ 20 years old	no	1)Medical incident reports submitted by fire department paramedics for all patients who received advanced life support by Seattle Fire Department/EMS personnel 2) Any missing data from above obtained from death certificates or hospital admission forms*
Chugh, et al,. 2004(16) and Chugh, et al., 2008(19)	≤1 hour of symptoms if witnessed or ≤24 hrs if unwitness ed	Not specified	Cardiac cause	Witnessed or unwitnesse d	No age criteria	yes	1) Case ascertainment from EMS system (78%), county medical examiner’s office (20%), and 16 area hospitals (2%). Of 353 cases, 280 identified by EMS; 68 by medical examiner; and 5 by hospital or provider 2) Postmortem exam performed at discretion of medical examiner or physician 3) Death certificate data from Oregon State Health Division 4) Available medical records
Nichol, et al., 2008(18)	Not specified	Out-of- hospital	Cardiac cause	Not specified	No age criteria (infants , childre n, and adults all include d)	yes	1) Resuscitation Outcomes Consortium (ROC), a clinical research network consisting of 11 sites and 1 central coordinating center, conducting clinical research on cardiopulmonary arrest and traumatic injury. ROC created a registry, ROC Epistry-Cardiac Arrest, which is a prospective, multicenter, observational registry of out-of-hospital arrests in EMS agencies and 11 institutions (8 US, 3 Canadian) 2) Multiple case ascertainment strategies used: telephone notification of each incident defibrillator use or CPR by EMS, hand sorting through paper EMS charts, electronic queries of EMS records using various data fields such as dispatch type, vital signs, or diagnosis,

CPR = cardiopulmonary resuscitation; EMS = emergency medical services; ICD = International Classification of Diseases

^*% of data from each source not provided

^†The National Mortality Followback Survey is described as a random sample of 1% of U.S. resident deaths (except residents of Oregon) age 25 years or older in 1986(27).