Results indicate that mental illness, physical illness, and associated functional impairments represent domains of risk for suicide among people 50 years of age or older; however, not all older adults who experience severe declines in health or function become suicidal. Our findings suggest that people with relatively more severe illnesses, deteriorating health status, and functional disability who require inpatient and home care services constitute a subset at greater risk that should be targeted for screening and intervention.
The findings support previous research on the role of psychiatric illnesses as modifiable risk factors and a history of psychiatric hospitalization as a marker of suicide risk in older adults (Conwell et al., 2000
; Harwood et al., 2001
; Beautrais, 2002
; Waern et al., 2002b
; Chiu et al., 2004
). Single episode and recurrent major depressive disorder, anxiety disorders, and history of previous suicide attempts are particularly important and can be easily evaluated by service providers; inquiry about current and past history of mental illness and suicidal behavior should be part of each older patient’s baseline health history.
Dementia or delirium and primary psychotic disorders were not significantly associated with suicide in this sample, perhaps due to early mortality from suicide and other causes (Conwell et al., 1996
). As well, early stages of cognitive decline are likely to be difficult for informants to detect (Harwood and Jacoby, 2000
). Given that anxiety was associated with suicide, clinicians should remain alert for suicide risk among patients with significant anxiety, in particular when it occurs in combination with mood disorders (Fawcett et al., 1990
; Johnson et al., 1990
). The association of cancer and diseases of the CNS with suicide may be indicative of the strong relationship of these diseases to depression (Musselman et al., 1998
; Lyness et al., 2000
; Massie, 2004
); indeed, the hypothesis that depression serves as a moderator or mediator of the association between disease and suicide should be examined in future research. Arthritis was significantly more likely in controls than in suicides, perhaps because it was more often reported in those persons who have fewer more severe and life threatening conditions.
Functional limitations in the performance of basic (PSMS) and instrumental (IADL) activities of daily living, in addition to impairments ascribable solely to physical causes (KPSS), were significantly associated with suicide. Results of the multivariate models suggest that functional impairment may be a more robust indicator of suicide risk than physical health status. Functional assessment is central to the practice of geriatric medicine and psychiatry (Fretwell, 1990
). Disability may be more readily recognized and assessed than psychiatric disorders in later life, adding additional data for suicide risk assessment in general practice.
Physical illness and functional limitations may result in a pattern of medical service utilization that could serve as a signal for suicide risk. Use of home health aide or nursing service in the last month or year, and any inpatient medical/surgical hospitalization in the last year, were associated with suicide in our sample, but visits to primary care or medical/surgical providers in the last week or month were not. Our findings support past research indicating home health care utilization is a risk factor for suicide, perhaps because it is a marker for other known suicide risk factors such as social isolation, more severe illness burden, and functional impairment (Waern et al., 2003
Similar rates of outpatient medical/surgical care utilization may actually reflect unequal access to care, since the suicide cases, who have greater illness burden and hence greater need for care, are not receiving it. Nonetheless, the frequency with which older adults were seen in primary care settings before suicide reinforces its importance as a potentially productive venue for mounting preventive interventions. Therapeutic strategies within the primary care setting have been found effective in reducing suicidal ideation in elderly patients (Bruce et al., 2004
). Our observation that utilization of home aide services is associated with suicide risk suggests a second potential venue for selective interventions (Rowe et al., 2006
). Finally, although cases in this study were more likely to be prescribed antidepressants than the comparison group, an examination of the ratio of antidepressant treatment to mood disorder diagnoses indicates that depressed and suicidal older adults may be under-treated pharmacologically, supporting previous research (Fawcett et al., 1990
The use of a random digit dialing sampling method precluded our ability to provide data on available subjects who did not participate. The participation rate for case informants was comparable to or better than other PA studies (Chiu et al., 2004
), but nonetheless the number of potential case informants who refused to participate may reflect stigma against suicide or inadequate social support for suicide victims. In our sample, suicides were more likely to be unmarried, live alone, and had less recent contact with proxy informants than comparison subjects, perhaps introducing bias. Small sample size limited our ability to examine subgroups by age, gender, race, or socioeconomic status, and may have contributed to instances of Type II error in those domains that we could address. The PA method, although valid for the study of suicide (Kelly and Mann, 1996
), is a retrospective approach based on proxy reports. To minimize recollection bias, we conducted interviews as soon as possible after the suicide death. Our choice of a living, rather than deceased, comparison group was necessitated by our focus on physical factors as correlates of case status. Although use of an accidental-death comparison group may help to control bereavement, older adults who die by accident often have greater medical burden and impairment and psychiatric diagnoses (Prior et al., 1996
; Kibayashi et al., 2007
). Nevertheless, case proxies, having experienced the suicide death of a relative or friend, may have a biased recollection of subject characteristics compared to comparison-group proxies who did not experience such a traumatic event. As well, there is potential for bias with clinician-rated measures and extraction of data from medical and psychiatric records and during the consensus process, as reviewers could not be masked to case status. To mitigate these possibilities, we used standardized and structured interviews and objective measures, as well as a consensus diagnostic process (Maziade et al., 1992
). Our use of proxy report data for both suicides and comparison subjects also served to reduce method variance.