[Validation of an advance directive]

German Legislation has defined the legal significance of advance directives (AD). Nevertheless, many precast ADs are of limited help in clinical decision making. Empirical results are rare and controversial. The SUPPORT study showed that precast ADs had a tendency to being ignored. Value-based AD proved to be of help in the interpretation of patients' wills by physicians. We therefore investigated whether a value-based AD that can be individualized with the help of a check-box-system is a valid instrument of communicating the patient's preferences. This is the first validation of an AD.

In our study we evaluated the acceptance and practicability of an AD. Questionnaires and the AD itself were handed out to patients, relatives, and members of the nursing and medical staff. All were asked to fill out the AD, mark all unclear passages, make amendments to the AD if wanted and finally were asked to answer a questionnaire regarding the AD. The level of significance was defined at 5%, meaning that every "unwanted" answer exceeding 5% or passages with more than 5% of the total remarks were analyzed and it was checked whether changes to the AD should be made.

The return rate was 64.8% (201 of 310). The results were highly positive for the items "understandable" (81,6%), "clarifying" (65,7%), "helpful" (76,1%), and "sensible" (75,1%). 70% of patients and relatives stated that they were able to express personal wishes and values with this AD, as well as a majority of the medical staff (44% vs. 30%). The discrepancy between the groups was significant (ChiSq=13.11, p<.001). All paragraphs of the check-box-system were validated as understandable and clear in intention. Major concerns were the inability of expressing own wishes and values (by 16,4% of all participants) and the fear of later alterations (15,4%). According to the findings and the evaluations the AD was modified.

The value-based AD which is routinely used in a university hospital and which can be individualized by a check-box-system was broadly accepted by the test subjects and showed highly positive results with respect to the analyzed items. Only minor changes were derived from our study to hopefully raise its acceptance even more. The discrepancy between patients, relatives and the medical staff concerning the possibility to express one's wishes and values was surprising and in contradiction to former findings. However, our study cannot answer whether the higher level of distrust among medical staff can be explained by negative professional experiences.

The investigated AD with a check box system seems to be an adequate instrument to communicate patient's wishes and directives.