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Three out of five patients believe they will survive in-hospital arrest; only 17% do.
Numerous studies have investigated the patient factors that might influence how likely one is to survive a cardiac arrest. Researchers have paid particular attention to such factors as age, race, presence or absence of a cancer diagnosis, and associated comorbidities. Not surprisingly, older age has been shown to be significantly associated with a lower likelihood of survival to discharge following cardiac arrest.5,6
Ehlenbach and colleagues examined medical data from 433,985 Medicare patients 65 and older who underwent in-hospital CPR.5 Both older age and prior residence in a skilled nursing facility were found to be associated with poorer survival rates.5 Although neither study was able to define an upper-age cutoff for certain peri-arrest mortality, age affects overall survival likelihood in an inverse fashion, with those 85 and older having only a 6% chance of surviving to hospital discharge (see Figure 1, p. 18).1,5,6
The degree of comorbid illness can be used to help predict mortality following cardiac arrest. Review of data from the National Registry of Cardiopulmonary Resuscitation (NRCPR) identified particular comorbidities that portend poor post-arrest prognosis.6 In general, the more pre-existing comorbidities a patient has, the less likely they are to survive.6 The presence of hepatic insufficiency, acute stroke, immunodeficiency, renal failure, or dialysis were associated with lower survival rates (see Figure 2, right).6,7
Poor performance status on admission, defined as severe disability, coma, or vegetative state, was predictive of worse outcomes.6 Understandably, patients with hypotension and those who required vasopressors or mechanical ventilation also tended to have lower post-arrest survival rates.6
The presence of a cancer diagnosis is another prognostic factor of interest when considering the chances of surviving an arrest. Classically, CPR was thought to be a futile intervention in this patient population. Specific characteristics within this subset of patients have been shown to influence prognosis, and multiple studies have confirmed that cancer patients generally do worse after an arrest with an overall survival rate of only 6.2%.8 Survival rates tend to be lower in patients with metastatic disease, hematologic malignancies, a history of stem cell transplant, those who arrest within an ICU, and inpatients whose cardiac arrest was anticipated.8,9
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Figure 1: Age and Post-Cardiac Arrest Mortality in Hospitalized Adults
In fact, cancer patients whose hospital course followed a path of gradual deterioration showed a 0% survival rate.9 In patients with metastatic disease, poor performance status prior to arrest appeared to account for their particularly poor survival odds (this supports the intuitive, rule-of-thumb that sicker cancer patients have worse outcomes).8
Growing evidence suggests the probability of post-arrest survival is not equal between racial groups. Specifically, black or nonwhite race is associated with higher utilization of CPR and lower survival rates (see Figure 3, right).10 Among Medicare patients, Ehlenbach and colleagues found that black and nonwhite patients were much more likely to undergo CPR, presumably as a result of being less likely to opt for DNR status.5,10 Although this could account for the differences seen in survival rates among these populations, these findings also raise concerns about the possibility of racial disparities in medical care. A subsequent cohort study also suggested that blacks and nonwhites were less likely to survive following cardiac arrest.10 However, adjusted analysis revealed that these differences were strongly associated with the medical center at which these patients received care. Therefore, although being nonwhite does portend worse outcomes following an arrest, the increased risk is likely attributed to the fact that many of these patients receive care at hospitals that have poorer overall CPR performance measures.5,10