We used several sources to notify patients of the opportunity to participate in our study. Some potential participants had contacted Compassion and Choices of Oregon for information about accessing aid in dying. Compassion and Choices is an organisation that offers information and assistance to people who choose aid in dying in Oregon. In 2006 Compassion and Choices gave information to or attended the deaths of three quarters of patients who chose aid in dying.21
Other potential participants made an explicit request for aid in dying to a physician as outlined in the Death with Dignity Act. Ethics consultants and palliative medicine and oncology specialists in northwest Oregon invited these patients to participate. Patients referred from all sources contacted study personnel directly for more information about enrolling. All patients gave written informed consent to participate.
The study psychologist (ERG) administered all measures in the participant’s home. We used the MacArthur competence assessment tool to determine participants’ capacity to consent to research.22
Once enrolled, participants confirmed that they had expressed interest in obtaining aid in dying through Compassion and Choices or explicitly requested aid in dying from a physician. The protocol required exclusion of participants with cognitive impairment (23 or less on the Folstein McHugh mini-mental state examination or 7 or less on the short portable mental status questionnaire23 24 25
). The psychologist administered the hospital anxiety and depression scale,26
which includes seven depression items and seven anxiety items, each rated on a 0-3 scale. For the purposes of identifying cases and consistent with expert recommendations, we identified participants with hospital anxiety and depression scale depression scores of 11 or greater as “depressed” and those with anxiety scores of 10 or greater as “anxious.”27
The psychologist administered the 20 item Beck hopelessness scale,28
a well validated measure of hopelessness, which is a predictor of suicidal ideation and suicide attempts.29 30
We designated those with scores of 10 or greater as “hopeless.”
The psychologist completed the current mood disorder section of the structured clinical interview for American Psychiatric Association Diagnostic and Statistical Manual-IV axis I disorders (SCID-I), a standard research instrument for diagnosing mental disorders.31
Because knowing that the patient has requested aid in dying may influence diagnostic thresholds for depression, the SCID interview was audiotaped and the tapes were reviewed by a research psychiatrist (SKD) who did not know if the patient had requested aid in dying (19 audiotapes from terminally ill patients who had not requested aid in dying were randomly interspersed). Based on studies by Chochinov and colleagues,32
the severity of depressed mood or anhedonia needed to be at least moderate for the two weeks before the interview in order to reach the threshold for diagnosis. Chochinov et al also reported that when moderate thresholds were used for mood criteria, presence or absence of physical symptoms (such as weight loss or fatigue) no longer influenced categorisation of depression. Using an inclusive approach, we attributed all physical symptoms of depression to the diagnosis of depression, even if they might be a result of terminal disease. Thoughts of death or suicide and suicidal plans or attempts are criteria for major depressive disorder in the American Psychiatric Association Diagnostic and Statistical Manual.31
We attributed suicidal ideation to a diagnosis of depression only if the patient endorsed suicidal thoughts or plans aside from aid in dying. The final SCID diagnosis of major depressive disorder was reached by consensus if ERG and SKD disagreed. For the purposes of identifying cases of depression, we considered participants to be depressed if their SCID was positive or their hospital anxiety and depression scale depression score was 11 or greater.27
Participants rated their overall suffering in the two weeks before the interview on an 11 point scale with end points labelled 0=“I have not suffered” and 10=“I have suffered severely.”33
They rated their quality of life in the previous two weeks on an 11 point scale with 0=“Quality of life as good as it can be” and 10=“Terrible, very bad quality of life.” Participants rated their desire for death in the two weeks preceding the interview on an 11 point scale with end points labelled 0=“I desire to live as long as possible” and 10=“I have a strong desire to die soon.” Participants rated the influence of depression as a reason for requesting aid in dying on a scale on which 1=“depression not at all important in the decision to request a lethal prescription” and 5=“depression very important in the decision to request a lethal prescription.”
All participants diagnosed with major depressive disorder were notified of this result at the time of the study visit, and the study psychologist recommended treatment and offered to facilitate counselling. As is standard at our institution, a safety plan was developed so that all patients who seemed upset by participation in the study or were found to be imminently suicidal by means other than legalised assisted dying would be referred for an evaluation of mental health. Otherwise, participants were assured confidentiality in order to facilitate honest disclosure. We obtained information on outcomes—whether the study participant received a prescription of a lethal drug or died by lethal ingestion—six months or more after all other data collection was complete.
We present data as frequencies and proportions for categorical items and as means and standard deviations for normally distributed continuous items. We used Student’s t test to compare means. All tests were two tailed and α was set at 0.05.