The study had some limitations. The sample size was low with only 15 patients completing the pilot study. Initially a much larger sample size was planned, which could not be reach because of unexpectedly low recruitment rates and was therefore stopped prematurely. This might be due to the data collection method. Patients received and returned the documents via mail. Mail-surveys in general have response rates around 60% 13. Another reason could be the emotional reactions that are connectedwith considering end of life and end of life decisions. As this was a concern when the study was designed, explaining that participation could trigger anxiety and depression was part of the informed consent process. Furthermore, the Department of Psychooncology, University Medical Centre Goettingen was informed about the study and their contact details were placed in the informed consent form. After consultation with the local ethics commission, we did not assess the reasons for drop-out as to refrain from triggering emotional reactions again.
Another limitation is that participants were diagnosed at different stages in their history of treatment. Some were newly diagnosed with stage IV NSCLC and had just started treatment, as others had received treatment for years. Initial study design only included patients that had been newly diagnosed with NSCLC stage IV and had just started treatment. As recruitment rates were very low, the inclusion criteria were adapted to include patients who had NSCLC stage IV and were already treated. The initial concern was that a bias would be introduced as participants with a long history of disease and treatment might be more precise in their advance directives, as they are more familiar with complications and course of disease.
The disease-centred advance directive was tested only against the advance directive of the Bavarian state ministry of justice. Therefore, results are only limited to the difference between those two advance directives. To put the results into a broader perspective the results need to be validated in lager studies following this pilot.
Discussion of results
This data suggests that disease-centred advance directives might help physicians to understand their patients’ wishes more precisely and make treatment choices according to their wishes. Even though the sample size was not large enough to perform a sensitivity analysis, descriptive analysis showed that, when physicians made treatment decisions with the help of the disease-centred advance directive, decisions were more likely to be according to the patients’ wishes than when they made decisions with the help of the common advance directive in this pilot study.
Those results need to be confirmed in a larger sample size, but these results suggest that there was no underlying confounder. A disease-centred advance directive might indeed help physicians to better understand their patients’ wishes.
Furthermore, the results show that in most scenarios, physicians made the same treatment decisions as patients when a disease-centred advance directive was used. Exceptions were scenario 3 and 6, where there was no difference between the treatment decisions of physician and patient in control or intervention and scenario 8 were there was a minor difference. From a statistical point of view, scenario 3, 6 and 8 do not provide discriminatory power to answer the question which advance directive is more suited to translate the patients’ wishes to the physician. Therefore, these scenarios should be eliminated or altered in a larger study. From a medical care point of view, it is interesting that scenario 3 and 6 dealt with the question of receiving antibiotic treatment under stable disease (scenario 3) or progressive disease (scenario 6). Almost all patients wanted treatment in those scenarios, except a few who were indecisive. Scenario 8 described reduced capability to participate in daily life (severe fatigue) due to the side effects of treatment and asked if participants wanted to be resuscitated in the case of a cardiac arrest. Most participants decided against treatment. These data suggest that those wishes seemed to be communicated well and independent of which advance directives are used.
Integration into current research
With the rise of advance care planning, advance directives became a small part in fostering patients’ autonomy regarding end of life decisions 14–16, 2,17. Drafting and completing an advance directive is only a small part of advance care planning. Advance care planning aims to transform the act of writing down one’s treatment wishes into a continuing process that includes structures and procedures to keep conversation about treatment wishes going. It The process of advance care planning ensures that changes of heart are regarded and added to an already existing advance directive. Furthermore, advance care planning rises general awareness on end-of-life decision making and its importance for patients’ autonomy 18. Even though the advance directive is only a small piece of advance care planning it still plays an important role. Studies suggest that advance directives may help to reduce overtreatment and hospital admissions at the end of life 4,19,20. Still, it remains unclear, if that also means that treatment is in concordance with the patients’ wishes. Most studies use ICU or hospital admission as end points 4, without comparing it to the instructions given in the advance directive. Even though it can be assumed that most patients who possess an advance directive drafted it, because they do not want life-prolonging treatment, that is not necessary the content of every advance directive. Up to this point, only a few studies evaluated if the advance directive actually help health care providers to understand the patients’ wishes 21. Therefore, there is little data on how well health care providers understand patients’ treatment preferences and choices after reading their advance directive. Still, it remains an important question when it comes to end of life decision making, especially when it is not possible anymore to ask patients about their preferred treatment. Especially as there are many types of advance directives that differ greatly in their content and their approach on preserving the patients’ autonomy 22–25. Yet there is no validation process that shows that the advance directive indeed reflects the patients’ wishes and values and is correctly understood by health care providers.
Data from the acute care setting shows that advance directives remain an important tool to assess the patients’ wishes and foster their autonomy in acute care 26–28. Unfortunately, acute care providers often describe them as unclear, not applicable to the situation and unhelpful 26. This underlines the importance of implementing and validating advance directives that help health care providers to understand the patients’ treatment wishes. In this study we showed that an advance directive that is disease-centred might be more helpful.