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Etiology

White persons had fewer out-of-hospital cardiac arrests and higher rates of hospital admission and survival compared with black persons

ACP J Club. 1994 Mar-April;120:47. doi:10.7326/ACPJC-1994-120-2-047


Source Citation

Becker LB, Han BH, Meyer PM, et al. Racial differences in the incidence of cardiac arrest and subsequent survival. N Engl J Med. 1993 Aug 26;329:600-6.


Abstract

Objective

To determine if racial differences influence the incidence of cardiac arrest and survival.

Design

Cohort study of 2 years' duration.

Setting

Community study in Chicago.

Patients

6451 persons (mean age 67 y, 57% men, 50% white, 45% black) with cardiac arrest in whom paramedics had attempted resuscitation between January 1987 and December 1988. Denominators for incidence rates came from Chicago census data. Exclusion criteria were incomplete data, age < 18 years, or noncardiac causes of death.

Assessment of risk factors

Race, sex, age, paramedic- or bystander-witnessed cardiac arrest, bystander-initiated cardiopulmonary resuscitation (CPR), initial cardiac rhythm, and emergency vehicle response time were determined from dispatches, paramedic questionnaires, and hospital records.

Main outcome measures

Incidence of cardiac arrest, rate of hospital admission, and survival to hospital discharge.

Main results

Black men and women had a higher incidence of cardiac arrest than white men and women (relative risk for blacks compared with whites ranged from 2.4 in the youngest group to 1.3 in the oldest group). White persons had a higher rate of admission to the hospital than black persons (10.5% vs 6.3%, {95% CI for 4.2% difference 2.8% to 5.6%}*, P < 0.001) and a higher overall survival rate (2.6% vs 0.8%, {CI for 1.8% difference 1.2% to 2.4%}*, P < 0.001). White persons had a higher rate of bystander-witnessed cardiac arrest and bystander-initiated CPR than did black persons (49% vs 42%, P < 0.001; and 25% vs 18%, P < 0.001, respectively), a higher rate of ventricular fibrillation or ventricular tachycardia (26% vs 17%, P < 0.001), and shorter times from placement of the telephone call for emergency assistance to arrival of the paramedics (P < 0.001). No difference existed between groups for the rate of paramedic-witnessed cardiac arrest.

Conclusions

The incidence of out-of-hospital cardiac arrest was lower and rates of hospital admission and survival after cardiac arrest were higher for white persons compared with black persons. The association between racial differences and cardiac arrest and subsequent survival remained when all other predictive variables were controlled.

Sources of funding: American Heart Association of Metropolitan Chicago and Section of Emergency Medicine, University of Chicago.

For article reprint: Dr. L.B. Becker, MC 5068, 5841 South Maryland Avenue, University of Chicago Hospitals, Chicago, IL 60637, USA. FAX 312-702-3135.

*Numbers calculated from data in article.


Commentary

Cardiovascular risk factors, such as hypertension and diabetes, are more common among black than among white Americans. Coronary heart disease and stroke are also more prevalent. Nevertheless, certain cardiovascular diagnostic procedures are less often done in blacks (1). It is not surprising, then, that Becker and colleagues found that the incidence of both survival from and hospitalization for out-of-hospital cardiac arrest are lower among blacks than among whites. These data consistently show racial differences in the series of steps between the arrhythmic event and the outcome that predict survival or death.

The initial steps (i.e., that cardiac arrests among blacks are less frequently witnessed, less often accompanied by bystander-initiated CPR, and take slightly longer for paramedic response) may well be responsible for findings farther along in the sequence (i.e., that blacks are less likely to have a favorable cardiac rhythm when the paramedics arrive and are more likely to be pronounced dead in the emergency department). Other potential explanations, however, include more severe underlying disease among blacks because of uncontrolled risk factors and lower hospitalization rates because of racial or economic discrimination. Methodologic explanations include inadvertent inclusion of noncardiac causes of arrests (e.g., trauma), perhaps accounting for the strongest differences in younger people, and underestimation of the denominator by the use of census-based population size, thereby artificially inflating mortality rates among blacks.

The data in this study do not allow hypothesis testing for the causes of the racial differences observed. An approach to preventing racial differences in survival after cardiac arrest must await replication and further findings. In the meantime, it would be prudent for clinicians to be alert to the higher rate of cardiovascular risk factors among blacks.

Roberta B. Ness, MD, MPH
University of PittsburghPittsburgh, Pennsylvania, USA


Reference

1. Ayanian JZ. Heart disease in black and white [Editorial]. N Engl J Med. 1993;329:656-8.