Few studies have examined rate and predictors of self-harm in discharged psychiatric patients.

To investigate the rate, coding, timing, predictors and characteristics of self-harm induced somatic admission after discharge from psychiatric acute admission.

Cohort study of 2827 unselected patients consecutively admitted to a psychiatric acute ward during three years. Mean observation period was 2.3 years. Combined register linkage and manual data examination. Cox regression was used to investigate covariates for time to somatic admission due to self-harm, with covariates changing during follow-up entered time dependently.

During the observation period, 10.5% of the patients had 792 somatic self-harm admissions. Strongest risk factors were psychiatric admission due to non-suicidal self-harm, suicide attempt and suicide ideation. The risk was increased throughout the first year of follow-up, during readmission, with increasing outpatient consultations and in patients diagnosed with recurrent depression, personality disorders, substance use disorders and anxiety/stress-related disorders. Only 49% of the somatic self-harm admissions were given hospital self-harm diagnosis.

Self-harm induced somatic admissions were highly prevalent during the first year after discharge from acute psychiatric admission. Underdiagnosing of self-harm in relation to somatic self-harm admissions may cause incorrect follow-up treatments and unreliable register data.