Thursday, September 12, 2013
JAMA Internal Medicine (JIM, you'll always be Archives of Internal Medicine to me) has published a study of an outcome prediction tool for in-hospital cardiac arrest. Specifically, a tool to predict the rates of neurologically intact survival after an in-hospital arrest. The developers of the tool call it GO-FAR (Good Outcome Following Attempted Resuscitation).
One could imagine ways of re-titling it FORe-GO, if one chose to spend one's time imagine such things.
This is the best tool of its kind that I've seen, although one needs to be very clear about what it's actually predicting.
The paper mostly describes, in detail, the derivation and validation of the tool. I won't belabor this - they did a good job of it, used a large dataset, created a model, tested and validated it to get the best receiver operator curve, etc. The data come from the massive, US-based, 'Get With the Guidelines Registry' (which used to be called the National Registry of Cardiopulmonary Resuscitation). The GWGR collects standardized data on in-hospital cardiac arrests from 366 hospitals in the US (all types and regions of hospitals) (the national rate of CPR survival to discharge of 18% which most of us are aware of comes from the GWGR). The GO-FAR data come from arrests between 2007-2009 (51,000 patients).
Worth belaboring, because this is critically important in understanding if one chooses to use this as a tool to help patients understand CPR outcomes, is how they defined a good outcome: a Cerebral Performance Category (CPC) of 1. CPC of 1 means:
"The patient is conscious, alert, and able to work but might have mild neurologic or psychological deficits (such as mild dysphagia or minor cranial nerve abnormalities). Patients with a CPC score of 2 have moderate cerebral disability and are able to live independently and work in a sheltered environment. Disabilities may include hemiplegia, seizures, ataxia, dysphagia, or permanent memory or mental changes. Patients with CPC scores of 3 through 5 progress through severe cerebral disability, coma or vegetative state, and finally brain death."This is important because while I'll venture to claim that nearly everyone would agree CPC scores of 3-5 are dismal outcomes, I think there could be a substantial number of people for whom a CPC of 2 would be acceptable. Not welcomed, not a 'good outcome' (which is, granted, what the researchers here are trying to predict), but better than death for some. So to be clear, the GO-FAR tool predicts rates of survival to hospital discharge with a CPC of 1, every other outcome from a CPC of 2 to death are lumped together as bad outcomes.
GO-FAR is being explicitly developed to help inform discussions at the time of hospital admission, so they deliberately excluded patient/CPR characteristics which predict outcomes but wouldn't be available necessarily to the admitting clinician (such as initial rhythm after arrest, site of arrest as someone may be admitted to the floor then transferred to the ICU prior to arresting). The characteristics which survived their analysis and were included in the final index are below. They very nicely also mentioned what the overall survival to discharge with good outcome was in all of these categories (remember, this is not overall survival, this is survival with a CPC of 1). The overall survival with good outcome rate for the entire dataset (all-comers) is 10%.
- Neurologically intact/minimal deficits at time of admission - CPC of 1 (this predicted a better outcome; everything else here predicted worse outcome) (18%)
- Major trauma (reason for admission) (6%)
- Acute stroke (reason for admission) (3.7%)
- Metastatic solid tumor or any hematologic malignancy (5.2%)
- Septicemia (basically they mean active bacteremia here; not the sepsis syndrome) (3.6%)
- Medical non-cardiac diagnosis (reason for admission; ie, patients admitted with cardiac conditions did better) (5.6%)
- Hepatic insufficiency (bilirubin greater than 2mg/dl or AST more than 2 times the upper limit of normal) (4.4%)
- Admitted from a skilled nursing facility (3.2%)
- Hypotension or hypoperfusion (5.9%)
- Renal insufficiency (creatinine over 2mg/dl) or dialysis (6.4%)
- Pneumonia (5.2%)
- Age over 70; the older the worse the outcome (10.2% 70-74 down to 4.5% for over 85 years).