title: A Nationwide Cohort Study of the Association Between Hospitalization With Infection and Risk of Death by Suicide.
abstract: Findings suggest that infections might be linked to the development of psychiatric disorders and suicidal behavior. Large-scale studies are needed to investigate the effect of infection on the risk of suicide.
  
  
  
  To estimate the association between hospitalization with infection and the risk of death by suicide.
  
  
  
  Nationwide, population-based, prospective cohort study with more than 149 million person-years of follow-up. Data were analyzed with survival analysis techniques and were adjusted for sex, age, calendar period, cohabitation status, socioeconomic status, and the Charlson Comorbidity Index. Individual data were drawn from Danish longitudinal registers. A total of 7.22 million individuals 15 years or older living in Denmark between January 1, 1980, and December 31, 2011, were observed during a 32-year follow-up period.
  
  
  
  The risk of death by suicide was identified in the Danish Cause of Death Register. Incidence rate ratios (IRRs) and accompanying 95% CIs were used as measures of relative risk.
  
  
  
  In 7 221 578 individuals (3 601 653 men and 3 619 925 women) observed for a total of 149 061 786 person-years, 32 683 suicides were observed during the follow-up period. Among the suicides, 7892 (24.1%) individuals had previously been diagnosed as having an infection during a hospitalization. Hospitalization with infection was linked to an elevated risk of suicide, with an IRR of 1.42 (95% CI, 1.38-1.46) compared with those without prior infection. Dose-response relationships were observed with respect to the number of hospital contacts for different infections. For example, having 7 or more infections was linked to an IRR of 2.90 (95% CI, 2.14-3.93). The number of days of treatment for infections was associated with an elevated risk of suicide in a dose-response relationship. More than 3 months of hospital treatment was linked to an IRR of 2.38 (95% CI, 2.05-2.76). The population-attributable risk associated with hospitalization with infection accounted for 10.1% of suicides.
  
  
  
  An increased risk of death by suicide was found among individuals hospitalized with infection in prospective and dose-response relationships. These findings indicate that infections may have a relevant role in the pathophysiological mechanisms of suicidal behavior.
authors.affiliation: Faculty of Health Sciences, Copenhagen University Hospital, Copenhagen, Denmark2Mental Health Centre Copenhagen, Capital Region of Denmark, Denmark.
authors.forename: Helene
authors.initials: H
authors.lastname: Lund-Sørensen
authors.affiliation: Faculty of Health Sciences, Copenhagen University Hospital, Copenhagen, Denmark2Mental Health Centre Copenhagen, Capital Region of Denmark, Denmark.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Benros
authors.affiliation: Faculty of Health Sciences, Copenhagen University Hospital, Copenhagen, Denmark2Mental Health Centre Copenhagen, Capital Region of Denmark, Denmark.
authors.forename: Trine
authors.initials: T
authors.lastname: Madsen
authors.affiliation: Faculty of Health Sciences, Copenhagen University Hospital, Copenhagen, Denmark2Mental Health Centre Copenhagen, Capital Region of Denmark, Denmark.
authors.forename: Holger J
authors.initials: HJ
authors.lastname: Sørensen
authors.affiliation: Department of Mental Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
authors.forename: William W
authors.initials: WW
authors.lastname: Eaton
authors.affiliation: Mood and Anxiety Disorders Program, Department of Psychiatry, School of Medicine, University of Maryland, Baltimore5Rocky Mountain Mental Illness Research Education and Clinical Center, Veterans Integrated Service Network 19, Denver, Colorado6Military and Veterans Microbiome Consortium on Research and Education, Denver, Colorado.
authors.forename: Teodor T
authors.initials: TT
authors.lastname: Postolache
authors.affiliation: Faculty of Health Sciences, Copenhagen University Hospital, Copenhagen, Denmark2Mental Health Centre Copenhagen, Capital Region of Denmark, Denmark7iPSYCH, The LundbeckFoundation Initiative for Integrated Psychiatric Research, Aarhus, Denmark.
authors.forename: Merete
authors.initials: M
authors.lastname: Nordentoft
authors.affiliation: Mental Health Centre Copenhagen, Capital Region of Denmark, Denmark3Department of Mental Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
authors.forename: Annette
authors.initials: A
authors.lastname: Erlangsen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002423:Cause of Death; D015331:Cohort Studies; D003428:Cross Infection / Q000401:mortality; D003718:Denmark; D005260:Female; D005500:Follow-Up Studies; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D007239:Infections / Q000401:mortality*; D007902:Length of Stay / Q000706:statistics & numerical data; D008137:Longitudinal Studies; D008297:Male; D001523:Mental Disorders / Q000401:mortality; D008875:Middle Aged; D012008:Recurrence; D012042:Registries; D012307:Risk Factors; D013223:Statistics as Topic; D013405:Suicide / Q000706:statistics & numerical data*; D055815:Young Adult