Background Medical orders for the use of life-supports should be informed by patients' values and treatment preferences. The purpose of this study was to explore the internal consistency of patients' (or their family members') stated values, and the relationship between these values and expressed preferences.

Methods We conducted a prospective study in 12 acute care hospitals in Canada. We administered a questionnaire to elderly patients and their family members about their values related to end-of-life (EOL) care, treatment preferences and decisional conflict.

Results Of 513 patients and 366 family members approached, 278 patients (54%) and 225 family members (61%) consented to participate. Participants' most important stated values were to be comfortable and suffer as little as possible, to have more time with family, to avoid being attached to machines and tubes and that death not be prolonged. The least important stated value was that life be preserved. Based on prespecified expected associations between the various values measured, there were inconsistencies in participants' expressed value statements. With few exceptions, participants' expressed values were not associated with expected corresponding treatment preferences. Of the 109 (40%) patients and 95 (42%) family members who had made decisions about use of life-supports, 68 (56%) patients and 60 (59%) family members had decisional conflict.

Conclusions Decision-making regarding medical treatments at the EOL is inadequate. To reduce decisional conflict, patients and their families need more support to clarify their values and ensure that their preferences are grounded in adequate understanding of their illness and treatment options.

Trial registration number NCT01362855.