Predicting the risk of repetition after self harm: cohort study

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Abstract

INTRODUCTION: About one in six people repeat self harm within a year of an episode. Identifying people who are at risk of repetition is a key objective of assessment.We investigated the predictive value of risk assessments after an episode of self harm and compared assessments made by emergency department staff with those made by psychiatric staff. PARTICIPANTS, METHODS: Four hospitals provide emergency care in the cities of Manchester and Salford. As part of the Manchester and Salford self harm project (MASSH) we collected data on all people aged at least 16 who presented with self harm in 1997-2001.Doctors in the emergency department and, for those patients who received a psychiatric assessment, mental health staff completed comprehensive assessment forms (which included demographic items as well as details of the self harm episode, past history, and current mental state). The assessor was also asked for a global clinical assessment of the risk of repetition of self harm (low, moderate, or high). We used the MASSH database to determine whether people repeated self harm within 12 months of their first presentation. We calculated sensitivity, specificity, and positive predictive value for emergency department and specialist mental health risk assessments. RESULTS:Overall, 7612 individuals presented with self harm (10 173 episodes). Emergency department staff were more likely than psychiatric staff to assess the risk of repetition as high (proportion of individuals rated as high risk 19.9% (971/4879) v 9.6% (369/3828)). The higher the assessed risk, the greater the likelihood of repetition (table). For both groups, however, most repetitions were among people assessed as at low or moderate risk. Psychiatric assessments had a lower sensitivity but higher specificity and positive predictive value. Repeating the analyses on the 1402 people who received both assessments made little difference to these results. The agreement between assessments done by the two groups was modest ( = 0.17). The sensitivity and positive predictive value of assessments by both staff groups was higher for subjects with previous episodes compared with first time presenters (for example, for emergency department assessments sensitivity 37.8% v 14.2%). COMMENT:The predictive value of risk assessments after self harm was low. Emergency department staff were more cautious in their assessment of risk, rating more people as at high risk of repetition. Consequently, they identified a greater proportion of people who repeated (higher sensitivity), but fewer of those assessed as at high risk actually went on to repeat (lower positive predictive value). Exclusively high risk approaches to management after self harm are unlikely to be worth while. Restricting intervention to people identified as at high risk, even assuming a completely effective intervention, would prevent fewer than one fifth of repeat episodes.

Keyword(s)

Adolescent; Adult; Aged; Cohort Studies; England; Humans; Middle Aged; Research Support, Non-U.S. Gov't; Risk Assessment; Sensitivity and Specificity; prevention & control: Recurrence; prevention & control: Self-Injurious Behavior; standards: Clinical Competence; standards: Emergency Treatment; standards: Medical Staff, Hospital; standards: Psychiatry

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