Risk taking attitudes among persons who received an Amyloid PET Scan and their care partners: role of scan results and level of cognitive impairment

An estimated 5.3 million Americans had Alzheimer’s disease in 2015, the most prevalent cause of dementia. In 2013, the Centers for Medicare and Medicaid Services (CMS) acknowledged the value shown in clinical trials of amyloid PET scans supporting a diagnosis of AD among patients experiencing unexplained cognitive impairment. The Imaging Dementia–Evidence for Amyloid Scanning (IDEAS) study was established to examine how amyloid PET scans guide doctors in diagnosing AD and other dementias. From this parent study of persons with unexplained cognitive impairment, we created the 2017 CARE IDEAS survey study to introduce the voice of the patient and care partner. A care partner is who the patient identifies as being most involved in his/her health care. We focus on the following question asked separately of the patient and care partner (n=500): “Suppose there is a new technology that can return your [patient name] memory to normal but has a risk of death. What is the highest risk of death–if any–that you [patient name] would be willing to accept for this treatment? The number you give can be anywhere between 0% and 100%.” In this paper we ask: (1) What is the relationship between a positive scan result and risk preferences for the hypothetical risky treatment? (2) Do patients and care partners assess the patient’s preferences differently and if so, is this difference moderated by level of cognitive impairment? Multivariable models controlled for patient and care partner demographics, relationship (spouse, child, other), socioeconomics, and numeracy. Cognitive impairment was assessed using the self-reported ECOG-12, which inquired of cognitive and functional decline compared to 10 years ago. We find that (1) scan results are not associated with patient willingness to accept the hypothetical risky treatment. On average patients with a positive scan were willing to accept a maximum 27% risk of death compared to 26% among those with a negative scan. (2) In unadjusted analysis, patient risk preferences did not differ by whether they were reported by the patient or the care partner. Risk preferences differed across the patient and care partner, however, by the level of the patient’s cognitive impairment. In adjusted analyses, we find that more severe patient cognitive impairment positively influenced a care partner’s assessment that the patient would be more willing to accept the risky treatment. A one-point increase in ECOG-12 was associated with care partners believing the patient would be willing to take on an additional 6.9% points of risk of death over the patient’s own willingness. For context, mean ECOG-12 score=2.22 (0.72 sd). Disagreement in risk preferences for persons with cognitive impairment (some with AD) and their care partners has clinical implications. Care partners need to know that they are overestimating the patient’s own willingness to take on risky treatment, given that they will likely need to represent the patient’s preferences as cognitive impairment/memory loss progresses. Providers need to understand this discrepancy to formulate treatment plans that reflect patient preferences. Our findings could become especially salient as experimental treatments become available for AD.