Suicide Risk in Medical and Mental Disorders

JAMA Psychiatry | 2024, Vol. 81, No. 12, p. 1198 - 1206

Risk of Suicide Across Medical Conditions and the Role of Prior Mental Disorder

Søren Dinesen Østergaard, MD, PhD; Department of Affective Disorders, Aarhus University Hospital– Psychiatry, Aarhus, Denmark; Department of Clinical Medicine, Aarhus University, Aarhus, Denmark

Natalie C. Momen, PhD; Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; Department of Clinical Epidemiology, Aarhus University and Aarhus University Hospital, Aarhus, Denmark

Uffe Heide-Jørgensen, PhD; Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; Department of Clinical Epidemiology, Aarhus University and Aarhus University Hospital, Aarhus, Denmark

Oleguer Plana-Ripoll, PhD; Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; Department of Clinical Epidemiology, Aarhus University and Aarhus University Hospital, Aarhus, Denmark

Importance: According to the World Health Organization, more than 700,000 individuals worldwide die by suicide each year. Medical conditions likely increase the risk of suicide.

Objective: To (1) provide age- and sex-specific pairwise estimates of the risk of suicide across a comprehensive range of medical conditions, (2) investigate whether there is a dose-response-like relationship at play (ie, the higher the disability burden due to medical morbidity, the higher the risk of suicide), and (3) determine if the risk of suicide with medical conditions is particularly pronounced among those who had mental disorder preceding the medical conditions.

Design, setting, and participants: This cohort study was an observational study of population-based data for all individuals living in Denmark at some point between 2000 and 2020. The data analysis took place from September 2023 to May 2024.

Exposures: Thirty-one specific medical conditions, as well as prior mental disorder.

Main outcomes and measures: The main outcome was suicide. Associations between the 31 specific medical conditions, nested within 9 categories, and suicide were examined via Poisson regression, yielding incidence rate ratios (IRRs). Subsequent analyses included an interaction term to assess whether a previous hospital-treated mental disorder modified the associations. Finally, the association between the disability burden of medical conditions and suicide was examined for those with and without prior mental disorder, respectively.

Results: A total of 6,635,857 individuals (3,337,613 females and 3,298,244 males) were included in the analyses of the associations between medical conditions and suicide. Except for endocrine disorders, all categories of medical conditions were associated with a statistically significant increased risk of suicide (which was most pronounced for gastrointestinal conditions [IRR, 1.7; 95% CI,1.5-1.8], cancer [IRR, 1.5; 95% CI, 1.4-1.6], and hematological conditions [IRR, 1.5; 95% CI, 1.3-1.6]). Interaction between mental disorder and individual medical conditions did not seem to play a major role for suicide risk. For those without but not for those with mental disorders, there was a dose-response-like relationship between the disability burden of medical conditions and suicide.

Conclusions and relevance: Medical conditions are generally associated with increased risk of suicide in a dose-response-like manner. Individuals with hospital-treated mental disorders appear to be at such an elevated risk of suicide that additional disability associated with medical conditions has little impact in this regard.

“Understanding patterns between medical conditions and suicide may have relevance from a preventive perspective via identification of groups at particularly elevated risk of suicide. However, most previous studies have focused on suicide risk in selected medical conditions. Furthermore, they have rarely considered risk of suicide in both relative and absolute terms, nor risk of suicide associated with multiple medical conditions, where a dose-response– like relationship seems plausible. Thus, studies are needed to consider the relative and absolute risk of suicide across a wide range of medical conditions and to determine if there is a dose-response– like relationship at play: that is, the higher the disability burden due to medical morbidity, the higher the risk of suicide” (p. 1199).

“This population-based cohort study included all 6,635,857 individuals living in Denmark at some point between January 1, 2000, and December 31, 2020… In this study, we considered 31 specific types of medical conditions (eTable 1 in Supplement 1) nested within 9 broad categories: circulatory, endocrine, pulmonary, gastrointestinal, urogenital, musculoskeletal, hematological, cancers, and neurological. Individuals with medical conditions were identified by combining data from 2 sources: medical/surgical hospital diagnoses assigned during inpatient admissions, and outpatient and emergency visits from the Danish National Patient Register… Individuals who died by suicide were identified in the Danish Register of Causes of Death27 using ICD-10 codes” (p. 1199). 

“We found that most medical conditions were associated with a substantially increased risk of suicide and that socioeconomic position and immigrant status played only a minor role in this context. For those with medical conditions, suicide was more common for males than for females, which is also the case at the level of the general population in Denmark, but the point estimates for the associations between medical conditions and suicide tended to be higher for females. In both sexes, for those without mental disorder but, somewhat surprisingly, not for those with mental disorder, there was a clear relationship between the disability burden of medical disease and suicide: the higher the burden, the higher the risk of suicide” (p. 1203).

“The association with suicide was particularly strong for gastrointestinal conditions (driven by chronic liver disease and, hence, likely attributable to harmful use of alcohol), cancer, and hematological conditions(driven by HIV/AIDS). That adjustment for socioeconomic position and immigrant status had relatively little impact on the strength of these associations is likely due to the fact that Denmark is among the most socioeconomically equal countries in the world and provides universal healthcare to its citizens” (p. 1203 - 1204).

Elevated Suicide Risk with Certain Medical Conditions: Medical conditions—especially gastrointestinal disorders, cancers, and hematological conditions—were linked to significantly increased suicide risk (IRRs up to 1.7). This highlights the need for suicide prevention strategies in medical settings, particularly for patients receiving life-altering or stigmatized diagnoses.

Critical Period: First 6 Months Post-Diagnosis: The risk of suicide was highest within the first six months after diagnosis and decreased over time. This finding emphasizes the importance of early mental health support and monitoring immediately following a new medical diagnosis.

Dose-Response Relationship Without Prior Mental Disorder: Among individuals without hospital-treated mental disorders, suicide risk increased with greater disability burden from medical conditions. This suggests that the cumulative impact of physical health problems alone can significantly elevate suicide risk, pointing to the value of holistic care that includes psychological assessment even in the absence of psychiatric history.

Limited Added Risk with Prior Mental Disorder: For those already diagnosed with a mental disorder, additional disability from medical conditions did not further elevate suicide risk. These individuals were already at high risk, possibly due to severe psychiatric illness, underlining the need for consistent suicide prevention regardless of comorbid physical conditions.

Minimal Impact of Socioeconomic and Immigrant Status: Adjusting for socioeconomic position and immigrant status had little effect on the associations found. This suggests that in a universal healthcare system like Denmark’s, medical and psychiatric vulnerabilities may play a more central role in suicide risk than demographic variables.

Sex Differences in Suicide Risk: Men had a higher absolute risk of suicide, but women often had higher relative risk increases associated with medical conditions. These differences indicate a need for sex-specific suicide prevention approaches, considering both absolute risk and risk amplification by medical illness.

“While the register-based nature of this study is an obvious strength with regard to sample size, follow-up time, and lack of selection and report bias, it also comes with inherent limitations. Specifically, given the lack of data on people who did not seek treatment, and on diagnoses assigned by general practitioners and other private practice physicians who do not report diagnostic data to the Danish National Patient Register providing data for this study, there was under-detection of an unknown magnitude, which may have introduced bias. Relatedly, our use of psychiatric hospital diagnoses to operationalize mental disorder means that the results may not be representative of those with less severe mental disorders that did Original Investigation Research not require hospital treatment. Also, the registers do not hold information regarding the onset of the symptoms eventually leading to a diagnosis (or prescription for a drug for the treatment) of a medical condition or a mental disorder, which may have affected the estimation of the strength of the associations(IRRs) with suicide(particularly for the time-dependent IRRs). However, the temporal order of the conditions in relation to suicide was, per definition, not an issue. With regard to generalizability, the seeming lack of influence of socioeconomic position and immigrant status on the risk of suicide associated with medical conditions may not translate to countries and health care settings that are less socioeconomically equal than Denmark” (p. 1205).