Discussion

Summary

The findings confirm the increased odds of STB among adolescents and young adults with a chronic illness as compared with their healthy peers.6–10,25,26 Our prevalence estimates and measures of association with STB among adolescents and young adults with a chronic illness, although consistent with some studies,2,27 are lower than other population-based studies of young people with and without various chronic illnesses.8,25,28,29 These discrepancies are likely attributable to differences in study location, age of respondents (sampling), measurement, and covariate selection.

Whereas 2 of the studies that reported similar estimates were conducted in Canada,2,27 those with higher estimates were conducted elsewhere—United States, Europe, and New Zealand.8,28,29 Our study included a wider age range of adolescents and young adults as compared with previous work, which typically studied only older adolescents. Evidence suggests that the prevalence of STB and depression (which captures aspects of STB) is highest in late adolescence,8,30,31 which may partly contribute to differences in estimates.

Regarding measurement, we used the validated CIDI to assess 12-mo STB, contrasting with previous studies that used generic questions of lifetime STB. Although similar in their delivery to participants, generic questions of STB have not undergone extensive psychometric testing to ensure accuracy. These methodological differences can result in findings that are inconsistent and may limit comparisons across samples. The paucity of studies specifically examining associations between chronic illness and STB among adolescents and young adults signals the need for more research in this vulnerable population. This is particularly relevant given that approximately 1 in 10 participants in our study reported STB.

To isolate the association between chronic illness and STB, several covariates were modelled, including the presence of comorbid mood or substance use disorders. The interrelations among chronic illness, psychiatric disorder, and STB may represent a causal pathway. That is, having a chronic illness increases the risk for the development of psychiatric disorder, which in turn, increases the risk for STB. Such mediational pathways cannot be rigorously tested using cross-sectional data from the CCHS-MH. However, if such a pathway exists, the inclusion of psychiatric disorder would further attenuate the association between chronic illness and STB.

Noteworthy were the independent associations between several covariates and STB. First, the association between the number of chronic illnesses and STB mirrored that of our exposure of interest—presence of chronic illness—in that associations strengthened across the severity of STB. Second, the protective effect of socioeconomic advantage (indicated by educational attainment) was less prominent in our sample.1,32 This suggests that, in the context of having a chronic illness and adjusting for related factors (number of chronic illnesses, disability), socioeconomic status may be less influential in reports of STB among adolescents and young adults. Third, evidence for an association between smoking status and suicide attempts contributes to the converging knowledge base that smoking is a robust correlate of STB.33 Smoking prevention and cessation efforts for adolescents and young adults with chronic illness may be helpful in reducing the odds of STB. Fourth, the level of disability was also found to be associated with STB and may reflect dependency or social isolation caused by having a chronic illness.34 Interventions aimed at reducing the impact of disability on life activities for young people with chronic illness may prove beneficial in reducing STB.

The moderating effect of mood disorder on the association between chronic illness and suicidal thoughts is a novel finding. Although previous studies have noted a detrimental compounding effect of having physical–psychiatric comorbidity,8,10 no one has quantified this interaction. This finding is relevant because it suggests that adolescents and young adults with a chronic illness and comorbid psychiatric disorders might be the focus for targeted preventive interventions to reduce the incidence of suicidal thoughts, diminishing the odds of future suicide attempts.1–3

We speculate that adolescents and young adults with comorbid chronic illness and psychiatric disorders may not be accessing appropriate psychiatric services, which in turn increase their odds of STB. This finding may appear counter-intuitive given that adolescents and young adults with chronic illnesses often have regular contact with the health system, thus increasing the probability that their thoughts of suicide would be identified by a health professional. However, for adolescents and young adults with a chronic illness, the medical encounter may not provide adequate time to assess mental health, including suicidal thoughts.

While the notion that there is no health without mental health is becoming more pervasive,35 the physical and mental health systems remain segregated, and consultation-liaison psychiatric services are an exception rather than the norm, particularly in primary care. Furthermore, the age of our sample encompasses the time of transition from paediatric to adult health services, which may further impede access to appropriate psychiatric or supportive services, thereby predisposing adolescents and young adults with a chronic illness to STB.

The absence of other moderating effects is likely attributable to the low prevalence of suicidal plans and suicide attempts and, thus, the low statistical power to detect these effects in this sample. We encourage more research aimed at identifying these potential moderating effects.