Predictors of psychiatric inpatient suicide: a national prospective register-based study.

OBJECTIVE To study the incidence and risk factors of psychiatric inpatient suicide within a national cohort representing all psychiatric hospital admissions. METHOD This national prospective register-based study followed all psychiatric hospital admissions in Denmark from the date of patient admission until patient discharge or inpatient suicide over a 10-year study period from 1997 through 2006. By using survival analysis techniques, this study was the first to take the inpatient time at risk into account in the estimation of the suicide rate and the predictors of suicide among hospital-admitted psychiatric patients. RESULTS Among 126,382 psychiatric inpatients aged 14 years or older, 279 suicides occurred. The risk of inpatient suicide was high: 860 suicides per 100,000 inpatient years. Of those individuals who completed suicide, 50% died within 18 days of admission. The inpatient suicide rate significantly decreased, about 6% each year (HR = 0.94; 95% CI, 0.90-0.99), over this 10-year period. Several significant predictors of suicide were found, including the following: Patients with a bachelor's degree had a significantly higher hazard ratio (HR) of suicide compared with those with a primary school education (HR = 0.41; 95% CI, 0.29-0.60) or those with vocational training (HR = 0.54; 95% CI, 0.39-0.77). Having a personality disorder as a secondary diagnosis (all psychiatric diagnoses were made according to ICD-10) raised the risk of suicide (HR = 1.60; 95% CI, 1.01-2.53), as did having recent contact (within the last year) with a private psychologist (HR = 1.85; 95% CI, 1.05-3.28). Recent suicide attempt before admission to the hospital was associated with the highest risk of inpatient suicide (HR = 4.99; 95% CI, 3.57-6.96). CONCLUSIONS This study demonstrated a high risk of psychiatric inpatient suicide in Denmark of 860 per 100,000 inpatient years and also revealed several significant predictors of psychiatric inpatient suicide. Furthermore, the inpatient suicide rate decreased from 1997 through 2006 in Denmark.