Their paper is published in the Oct. 5 edition of the Journal of the American Medical Association.
The researchers added that if an additional 6% of decedents in high-use regions of the country had prepared treatment-limiting advance directives, "our estimates suggest that Medicare spending on the 790,061 beneficiaries dying in high-spending hospital referral regions in 2006 would have been $265 million lower."
One surprising finding is that in high Medicare spending areas, those who had advance directives and those who didn't had roughly the same use of aggressive life-sustaining treatments, such as mechanical ventilation, intubation, and parenteral nutrition, at the end of life.
"This may suggest that treatment-limiting advance directives are associated with a quicker withdrawal of these aggressive and expensive interventions, even if the likelihood of initiating these treatments is less strongly affected," Nicholas and colleagues wrote.
The researchers said one interpretation of their finding is that "advance directives are most effective when one prefers treatment that is different from the local norms. Thus, in high-intensity regions, more limited treatment requires an explicit statement."
"We urgently need studies to examine the extent to which greater advance directive use in high-intensity regions would result in treatment that is more concordant with patient preferences and to understand the patient, physician, and health system characteristics that lead to higher rates of use (of advance directives) in low-spending regions.