Final Progress Report

Proposal No. IBD-0217
Principal Investigator:  Henrik Toft Sørensen, Ph.D., Dr.Med.Sc.
Applicant Organization:  Aarhus University (Denmark)
Project Title:  The association between inflammatory bowel disease and completed suicide in the adult population of Denmark
Period of Award:  January 1, 2008 – February 28, 2009

i. Summary of Project Aims

The aims of the current project, as stated in the original grant proposal, were as follows: 

This study has three specific aims. The first specific aim is to describe and compare the prevalence of depression, anxiety, psychosis and attempted suicide among people with Crohn’s disease and ulcerative colitis who commit suicide to those who do not commit suicide. The second specific aim of this study is to examine the association between Crohn’s disease and completed suicide. The third specific aim of this study is to examine the association between ulcerative colitis and completed suicide. Since earlier studies have found that the prevalence of psychiatric illness differs between Crohn’s disease and ulcerative colitis, with greater psychiatric comorbidity among people with Crohn’s disease, these two illnesses will be examined separately. 

ii. Accomplishments towards Meeting Aims

We were successful in meeting all three aims of the proposed study, with slight modifications due to data availability. With regard to the first aim, we were able to examine the prevalence of depression, substance abuse, anxiety disorder and reaction to severe stress diagnoses among people with both Crohn’s disease and ulcerative colitis compared to people without these diagnoses. We were also able to further examine the prevalence of depression, substance abuse, anxiety disorder and reaction to severe stress diagnoses among people with both Crohn’s disease and ulcerative colitis among those who completed suicide and those who did not. With regard to the second and third aims, we successfully completed an examination of the associations between Crohn’s disease and completed suicide and ulcerative colitis and completed suicide. These associations were examined separately.

iii. Significant Results

The current study included 27,053 suicide cases and 551,060 controls from the general population of Denmark, matched to cases on gender, exact date of birth, and calendar time. Forty suicide cases (0.15%) were diagnosed with Crohn’s disease compared with 554 controls (0.10%). Eighty-seven suicide cases were diagnosed with ulcerative colitis (0.32%) compared with 1184 controls (0.21%).
With regard to the first aim, generally, we found an increased prevalence of depression, substance abuse, anxiety disorder, and reaction to severe stress diagnoses among people with Crohn’s disease and ulcerative colitis compared to people without these diagnoses (see Table 1). The one exception was substance abuse diagnoses among people with ulcerative colitis, which was found to be as common as these diagnoses among people without ulcerative colitis. 

With regard to the second aim, we found that people diagnosed with Crohn’s disease had 1.6 times the rate of completed suicide, compared with people without a Crohn’s disease diagnosis (95% confidence interval: 1.1, 2.2). Interestingly, this association held even when adjusted for demographics, co-morbid depression, substance abuse, anxiety disorder, and reaction to severe stress diagnoses. In other words, we found an association between Crohn’s disease and suicide that was independent of these factors. 

With regard to the third aim, we found that people diagnosed with ulcerative colitis had 1.5 times the rate of completed suicide, compared with people without an ulcerative colitis diagnosis (95% confidence interval: 1.2, 1.9). Similarly to our Crohn’s disease findings, this association held even when adjusting for demographics, co-morbid depression, substance abuse, anxiety disorder, and reaction to severe stress diagnoses. Interestingly, we also found an interaction between ulcerative colitis and depression and ulcerative colitis and anxiety disorders, indicating that those with both ulcerative colitis and depression or both ulcerative colitis and anxiety disorders had an increased rate of suicide compared to the rate that would be expected based on the individual rate among people with either ulcerative colitis, depression or anxiety disorder diagnoses alone.

iv. Lay Summary

This project examined the association between inflammatory bowel disease (IBD) and suicide. Additionally, we explored the prevalence of depression, substance abuse, reactions to severe stress, and anxiety disorders among people with and without IBD. Studies have shown that depression, anxiety, and suicide mortality may be problems people with IBD encounter. However, research studies in this area are limited and many clinicians who treat IBD do not integrate screening for mental illness or suicidal behavior in their clinical care. Using data contained in the Danish health care registries from 1981–2006, we conducted three main analyses. The first compared the percentage of people diagnosed with depression, substance abuse, reactions to severe stress, and anxiety disorders among people diagnosed with either ulcerative colitis (UC) or Crohn’s disease (CD) to the percentage of people diagnosed with depression, substance abuse, reactions to severe stress, and anxiety disorders among people with UC or CD. The second analysis examined the association between being diagnosed with UC and committing suicide and the final analysis examined the association between being diagnosed with CD and committing suicide. We found that people with CD or UC had an increase prevalence of depression, substance abuse, reactions to severe stress, and anxiety disorders with one exception – substance abuse diagnoses were equally common among people with and without UC. Additionally, we found that those with CD or UC had a modestly increased rate of suicide compared with those without these diagnoses and those with UC and depression or UC and anxiety disorders may be at particular risk for suicide. The current study adds to existing evidence in support of screening for psychiatric illness among patients with IBD and screening for suicidality, particularly among patients with comorbid UC and depression or anxiety disorders.