It is unclear whether health service use influences the association between psychiatric and physical co-morbidity and suicide risk in older adults.

Controls were older adults (n = 2,494) participating in a longitudinal study on the health of the elderly carried out between 2004 and 2007, in Quebec. The cases were all suicide decedents (n = 493) between 2004 and 2007, confirmed by the Quebec Coroner's office. Multivariate analyses were carried out to test the association between suicide and the presence of psychiatric and physical illnesses controlling for health service use and socio-demographic factors by gender and age group. Interaction terms were also tested between suicide and co-morbidity on outpatient service use.

The presence of physical illnesses only, was associated with a reduced risk of suicide across all sex and age groups. The presence of a mental disorder only was associated with an increased risk of suicide overall and specifically in females and those aged 70 to 84 years of age. Suicide risk was lower in those with a psychiatric and physical co-morbidity and consulting mental health services.

Increased mental health follow-up in older adults with psychiatric illnesses is needed for the detection of suicidal behavior and reducing suicide risk in males. Further research should focus on the mitigating effect of the presence of physical illnesses on stigma and health service use and the presence of social support in the elderly.