The American Heart Association guidelines say that survival rates below 1% are "futility," but all groups have better survival than that.
Even among very sick patients at least 10% survive: A study of CPR in a sample of US hospitals from 2001 to 2010, where overall survival was 19%, found 10% survival among cancer patients, 12% among dialysis patients, 14% over age 80, 15% among blacks, 17% for patients who lived in nursing homes, 19% for patients with heart failure, and 25% for patients with heart monitoring outside the ICU.

Another study, of advanced cancer patients, found the same 10% survival mentioned above.

A study of Swedish patients in 2007-2015 with ECG monitors found 40% survived at least 30 days after CPR at ages 70–79, 29% at ages 80–89, and 27% above age 90.

An earlier study of Medicare patients in hospitals 1992-2005, where overall survival was 18%, found 13% survival in the poorest neighborhoods, 12% survival over age 90, 15% survival among ages 85–89, and 17% survival among ages 80–84.

Swedish patients over 90 had 15% survival to hospital discharge, 80-80 had 20%, and 70-79 had 28%.

A study of King County WA patients who had CPR outside hospitals in 1999-2003, where 34% survived to hospital discharge overall, found that among patients with 4 or more major medical conditions, 18% survived; with 3 major conditions 24% survived, and 33% of those with 2 major medical conditions survived.

Nursing home residents' survival has been studied by several authors,
and is measured annually by the Cardiac Arrest Registry to Enhance Survival (CARES).
CARES reports CPR results from a catchment area of 115 million people, including 23 state-wide registries, and individual communities in 18 other states as of 2019.
CARES data show that in health care facilities and nursing homes where AEDs are available and used, survival rates are double the average survival found in nursing homes overall.

Gepgraphically, there is wide variation state-to-state in survival after CPR in US hospitals, from 40% in Wyoming to 20% in New York, so there is room for good practices to spread, raising the averages.

For CPR outside hospitals, survival varies even more across the US, from 3% in Omaha to 45% in Seattle in 2001.
This study only counted heart rhythms which can respond to defibrillator shocks (tachycardia).

A major reason for the variation has been delay in some areas between the call to emergency services and the departure of medics, and then arrival and treatment.
Delays were caused by lack of monitoring, and the mismatch between recruiting people as firefighters, though most emergency calls they are assigned to are medical, so staff resisted and delayed on the medical calls.
Building codes have cut the number of fires, but staff still think of themselves as firefighters.
The American Heart Association guidelines say that survival rates below 1% are "futility," but all groups have better survival than that. Even among very sick patients at least 10% survive: A study of CPR in a sample of US hospitals from 2001 to 2010, where overall survival was 19%, found 10% survival among cancer patients, 12% among dialysis patients, 14% over age 80, 15% among blacks, 17% for patients who lived in nursing homes, 19% for patients with heart failure, and 25% for patients with heart monitoring outside the ICU. 
Another study, of advanced cancer patients, found the same 10% survival mentioned above.
A study of Swedish patients in 2007-2015 with ECG monitors found 40% survived at least 30 days after CPR at ages 70–79, 29% at ages 80–89, and 27% above age 90.
An earlier study of Medicare patients in hospitals 1992-2005, where overall survival was 18%, found 13% survival in the poorest neighborhoods, 12% survival over age 90, 15% survival among ages 85–89, and 17% survival among ages 80–84.
Swedish patients over 90 had 15% survival to hospital discharge, 80-80 had 20%, and 70-79 had 28%.
A study of King County WA patients who had CPR outside hospitals in 1999-2003, where 34% survived to hospital discharge overall, found that among patients with 4 or more major medical conditions, 18% survived; with 3 major conditions 24% survived, and 33% of those with 2 major medical conditions survived.
Nursing home residents' survival has been studied by several authors,
and is measured annually by the Cardiac Arrest Registry to Enhance Survival (CARES). CARES reports CPR results from a catchment area of 115 million people, including 23 state-wide registries, and individual communities in 18 other states as of 2019. CARES data show that in health care facilities and nursing homes where AEDs are available and used, survival rates are double the average survival found in nursing homes overall.
Gepgraphically, there is wide variation state-to-state in survival after CPR in US hospitals, from 40% in Wyoming to 20% in New York, so there is room for good practices to spread, raising the averages.
For CPR outside hospitals, survival varies even more across the US, from 3% in Omaha to 45% in Seattle in 2001. This study only counted heart rhythms which can respond to defibrillator shocks (tachycardia).
A major reason for the variation has been delay in some areas between the call to emergency services and the departure of medics, and then arrival and treatment. Delays were caused by lack of monitoring, and the mismatch between recruiting people as firefighters, though most emergency calls they are assigned to are medical, so staff resisted and delayed on the medical calls. Building codes have cut the number of fires, but staff still think of themselves as firefighters.
Cardiopulmonary resuscitation