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Readers of systematic reviews will be used to seeing authors conclude that research conducted to date provides insufficient evidence to guide the management of patients with a particular condition. Such was the case when Hawton and colleagues updated their Cochrane review of interventions following deliberate self-harm (DSH) in 1999.1 The authors added the familiar plea that future studies should recruit larger numbers of participants in order to be sufficiently powered to be able to detect clinically significant differences in outcomes.
The proportion of people who re-present to medical services with repeated self-harm within a year of an initial incident is known to be between 13% and 18%.2 Over 600 people would be needed in a standard “two arm” trial in order to have an 80% chance of demonstrating a clinically significant reduction from 15% to 10% in the level of repetition of self-harm at a 0.05% level. Before the turn of the century, the largest trial that had been conducted involved only 516 people.3 This study examined the impact of adding a home visit to standard care following an episode of self-harm and demonstrated a non-statistically significant trend towards reduced repetition among those who received a visit.
Unlike most other areas of mental health research, recent years have seen the completion of a number of large DSH trials which have been sufficiently powered to detect clinically significant differences in patient outcomes (see table⇓). So what do these studies tell us about the management of patients who self-harm?
FINDINGS FROM RECENT RANDOMISED TRIALS
The largest trial conducted to date explored the effects of brief primary care-based intervention.4 In this study general practitioners (GPs) were contacted every time a patient registered with their practice presented to a local emergency department following …
For correspondence: Dr M J Crawford, Department of Psychological Medicine, Imperial College London, Claybrook Centre, Claybrook Road, London W6 8LN, UK;
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