Our results challenge current policy and law advocating instructional advance directives as a means of honoring specific patient wishes at the end of life. Future research should explore other methods of improving surrogate decision making and consider the value of other outcomes in evaluating the effectiveness of advance care planning.

More than one in three seriously ill persons who prefer comfort care believe that their medical care is at odds with their preference that treatment focus on palliation. Such discord was associated with higher 1-year healthcare costs and increased survival.

Although ADs do not improve the accuracy of substituted judgments for primary care physicians or family surrogates, they increase the accuracy of hospital-based physicians. Primary care physicians are withdrawing from hospital-based care in growing numbers, and emergency medicine and critical care specialists most often are involved in decisions about whether to begin life-sustaining treatments. If ADs can help these physicians better understand patients' preferences, patient autonomy more likely will be preserved when patients become incapacitated.

The use of instructional advance directives assumes that preferences for life-sustaining medical treatment remain stable over time and across changes in life condition. A sample of 332 older adults recorded their preferences for 4 life-sustaining treatments in 9 illness scenarios. These preferences were elicited again 1 and 2 years after the original interview. Overall, preferences for life-sustaining treatment were moderately stable over time, but stability varied significantly across judgments. Preferences were most stable for illness scenarios that were most and least serious and for decisions to refuse treatment. Age, gender, education, and prior completion of an advance directive were all related to preference stability, and evidence indicated that declines in physical or psychological functioning resulted in decreased interest in life-sustaining treatment.