BACKGROUND: Repetition of hospital-treated self-poisoning and admission to psychiatric hospital are both common in individuals who self-poison.

AIMS: To evaluate efficacy of postcard intervention after 5 years.

METHOD: A randomised controlled trial of individuals who have self-poisoned: postcard intervention (eight in 12 months) plus treatment as usual v. treatment as usual. Our primary outcomes were self-poisoning admissions and psychiatric admissions (proportions and event rates).

RESULTS: There was no difference between groups for any repeat-episode self-poisoning admission (intervention group: 24.9%, 95% CI 20.6-29.5; control group: 27.2%, 95% CI 22.8-31.8) but there was a significant reduction in event rates (incidence risk ratio (IRR) = 0.54, 95% CI 0.37-0.81), saving 306 bed days. There was no difference for any psychiatric admission (intervention group: 38.1%, 95% CI 33.1-43.2; control group: 35.5%, 95% CI 30.8-40.5) but there was a significant reduction in event rates (IRR = 0.66, 95% CI 0.47-0.91), saving 2565 bed days.

CONCLUSIONS: A postcard intervention halved self-poisoning events and reduced psychiatric admissions by a third after 5 years. Substantial savings occurred in general hospital and psychiatric hospital bed days.

Hospital-treated self-poisoning is common in Australia1,2 and hospital-treated self-harm is common in the UK.3,4 Self-poisoning is the most common variant of self-harm and most patients make initial contact with hospital through the emergency department.5 Repetition of self-harm is common; with, within 1-4 years of an index episode, a median rate of 21% and after more than 4 years a median rate of 23%.6 Self-harm has a strong association with subsequent suicide as well as significant resource implications for the health system.6 Only three interventions in randomised controlled trials have reported reductions in the proportion of participants with repetition of self-harm beyond the duration of the intervention: 5-month follow-up after four sessions of interpersonal therapy;7 18-month8 and 5-year follow-up9 for a day hospital programme using mentalisation techniques; and 12-month follow-up10 for dialectical behaviour therapy. One study has demonstrated a reduction in the event rate of self-poisoning after 12 months of follow-up.11 Only two trials have reported reductions in admissions to psychiatric hospitals beyond the duration of the intervention; hospital-based mentalisation9 and dialectical behaviour therapy.10 One study has demonstrated the cost-benefits for hospital-based mentalisation after 36-month follow-up, with no cost differences between the groups during pre-treatment or treatment and costs of partial hospital treatment offset by less psychiatric in-patient care and reduced emergency room treatment.12

In this study we aimed to test the efficacy of a postcard intervention in hospital-treated patients who had self-poisoned over 5 years (4 years’ follow-up after cessation of the intervention). There were two primary outcomes: general hospital admissions for repetition of self-poisoning and psychiatric admissions for any reason. For each primary outcome we examined differences in proportions for any admission and event rates for the number of admissions per person. Secondary binary end-points were all-cause mortality and suicide.