The paper by Harriss et al (Reference Harriss, Hawton and Zahl2005) addresses the very relevant issue of measuring suicide intent in the evaluation of future suicide risk. Measuring suicide intent is more useful than measuring the lethality of the attempts (i.e. the degree of danger to life resulting from self-injurious behaviour; Reference Beck, Beck and KovacsBeck et al, 1975). Assessing the intent can be particularly useful in situations where there is no correlation between the expected and actual outcome of the method used as may happen in those with a low level of literacy. Accuracy of expectations about the likelihood of dying moderates the relationship between suicide intent and medical lethality (Reference Brown, Henriques and SosdjanBrown et al, 2004).

Identifying a cut-off to differentiate between high-intent and low-intent attempts is very difficult. Median scores on the Suicide Intent Scale (SIS) were used by Harriss et al (Reference Harriss, Hawton and Zahl2005) to categorise high-intent and low-intent attempts. Their results showed that women with high intent repeat suicide attempts whereas men with low intent tend to do so. Since there was a gender difference in the median values, the cut-off score used for males (10) was higher than that used for females (8). By virtue of using separate cut-off scores, men were classified as having low intent even if they had similar scores on the SIS to women in the high-intent group, possibly affecting the repetition rates. Quantifying and classifying suicide intent have been approached in different ways by various researchers. Baca-Garcia et al (Reference Baca-Garcia, Diaz-Sastre and Resa2004) studied the characteristics which influence emergency psychiatrists in decisions to hospitalise after a suicide attempt, and found that a cut-off of 11 on the SIS correctly classified 72% of participants. However the authors clearly acknowledge the advantages of using an extensive clinical checklist over an instrument such as the SIS. Although the SIS was not originally designed to predict repetition of self-harm, it may be possible to identify similar cut-off points to predict the likelihood of repetition of suicide attempts when used with other known risk factors. For any risk assessment to be clinically meaningful it should be based on a composite index which takes into account various factors, including the level of suicide intent, the severity of depression, the degree of hopelessness, the impact of life events and the lethality of the attempt.