Postcards from the EDge: 24-month outcomes of a randomised controlled trial for hospital-treated self-poisoning

Background Repetition of self-poisoning is common. Aims To report the 24-month outcomes of a non-obligatory postcard intervention (plus treatment as usual) compared with treatment as usual. Method In a randomised-controlled trial (Zelen design) conducted in Newcastle, Australia, eight postcards were sent to participants over a 12-month period. The principal outcomes were the proportion of participants with one or more repeat episodes of self-poisoning and the number of repeat episodes per person. Results No significant reduction was observed in the proportion of people repeating self-poisoning in the intervention group (21.2%,95% CI 17.0-25.3) compared with the control group (22.8%,95% CI 18.7-27.0; chi(2)=0.32, d.f.=1, P=0.57); the difference between groups was - 1.7% (95% CI - 7.5 to 4.2). There was a significant reduction in the rate of repetition, with an incidence risk ratio of 0.49 (95% CI 0.33-0.73). Conclusions A postcard intervention maintained the halving of the rate of repetition of hospital-treated self-poisoning events over a 2-year period, although it did not significantly reduce the proportion of individuals who repeated self-poisoning.