• drug overdose;
  • Japan;
  • prospective cohort study;
  • suicide attempt


The aim of the study was to investigate the incidence of and risk factors for repetition of suicidal behavior within a year after admission for drug overdose in Japan.


Patients admitted to the emergency department of a general public hospital in Tokyo for drug overdose of prescribed medicine and/or over-the-counter drugs between March 2008 and February 2009 were followed up after 1 year. Demographic characteristics, previous suicide attempts, and mental health state were examined by self-report questionnaire and interview at recovery from the initial attempt. Information about suicidal behavior during the follow-up period was obtained from the outpatient psychiatrists by postal questionnaire 1 year after discharge.


Of 190 patients admitted to the emergency department, 132 patients answered the questionnaire and had the interview. Information about thefollow-up period for 66 patients was obtained. Of the 66 patients, 28 patients attempted suicide again and two patients committed suicide during the 1-year follow-up period. Psychiatric diagnosis of personality disorder and denial of suicidal intent at the time of recovery were associated with increased risk for another suicide attempt. Lethality levels of suicidal behaviors before and after admission were associated with each other.


The rate of fatal and non-fatal suicide attempt within a year after admission for self-poisoning was substantial. Psychiatric diagnosis of personality disorder was a risk factor for repetition of suicide attempt. Clinicians should pay attention to the means of previous suicide attempts even though the patient denies suicidal intent at recovery.