BOSTON – The risk of suicide in older adults is higher among patients with cancer than among those with other medical illnesses, even after controlling for psychiatric illness and the risk of dying within 1 year, Dr. Matthew Miller reported at the annual meeting of the American Association of Suicidology.
Multiple studies have demonstrated that physical illness is a common antecedent to suicide in elderly people, and it has been proposed that elderly cancer patients are especially vulnerable, possibly because of an increased risk of depression, according to Dr. Miller of the Harvard School of Public Health, Boston.
To determine whether the risk of suicide is greater among elderly patients with cancer than among those with other medical illnesses, Dr. Miller and his colleagues evaluated the suicide risk associated with medical illness among older Americans in a case control study.
The investigators used health care utilization data linked to prescription and mortality files for a cohort of New Jersey Medicare recipients who received prescription medication for any medical illness during the period of study, and determined that, of 1,408 Medicare recipients aged 65 years and older who were receiving pharmaceutical assistance from 1994 to 2002, 128 died by suicide, predominantly by firearm. For comparative analysis, the remaining 1,280 patients were frequency-matched to case patients for age, gender, and race, Dr. Miller said.
In a multivariate model adjusted for age, sex, race, medical and psychiatric comorbidity, and the use of prescription medications, “the only medical condition associated with suicide was cancer,” Dr. Miller said, noting that cancer patients had a more than twofold greater risk of suicide.
Diagnoses of affective disorder and anxiety/personality disorder were similarly associated with suicide in the adjusted model, with respective odds ratios of 2.3 and 2.2, as were treatment with antidepressants and treatment with opioid analgesics, with respective odds ratios of 2.0 and 1.6, he said.
The reasons behind the increased risk of suicide among cancer patients require further empirical assessment, Dr. Miller said in an interview. “I suspect, based on work by other investigators, that hopelessness plays a large role, and that functional limitations and social support contribute as well.”
It's possible, he continued, “that some insight can be found in Susan Sontag's provocative musings in “Illness as Metaphor and AIDS and Its Metaphors” (New York: St. Martin's Press, 2001), which suggest that a component of the disproportionate risk of suicide in cancer patients is related to the premium placed on the prospect of a life lived free of cancer, a notion epitomized and reinforced by the words commonly used to describe the goals of cancer therapy, such as “cure” and “disease-free survival.”
It is also possible that the cancer itself or the chemotherapy used to treat the cancer could result in mental status changes that are risk factors for suicide; “unfortunately, our data are too sparse to address this speculation,” he stated.
With respect to prevention, “because hopelessness and depression are not identical, clinical interventions may need to address both of these dimensions of psychic conflict,” Dr. Miller said. “Certainly, addressing underlying depression is important, and a first step would be to rigorously screen for depression among patients diagnosed with cancer, especially soon after the diagnosis and at critical clinical junctures.”
And although interventions aimed at addressing hopelessness in cancer patients have not been studied in any detail, “psychotherapeutic interventions that focus on existential issues and focus on attenuating pessimistic cognitions or even spirituality centered interventions to address existential conflicts may help decrease hopelessness,” he said.
Finally, given the established link between access to firearms and suicide, both in this cohort and in the United States as a whole (J. Trauma 2007;62:1029-34), lethal-means counseling should be considered for at-risk patients, according to Dr. Miller.
“Lethal-means counseling refers to speaking with patients at heightened risk for suicide and their families about reducing their access to firearms,” he said.
“The goal of such counseling is to reduce the odds that a suicide attempt ends in death.”