So not much effect then....
The paper by Vaiva et al is an admirable attempt to use a brief
intervention after self posioning - one phone call at four weeks or three
months - to reduce the repetition rate after about a year. However several
questions arise from this study. Firstly the rationale behind thinking
that a single phone call would make a difference at one month or three
months is obscure. We know that most repetitions of self harm occur in the
month after the index attempt when individuals are in crisis. An
intervention that would make more clinical sense would be a phone call
within 48 hours of the index attempt.
Secondly it is hard to undertand the authors power calculation as we
are not told on what outcome it is powered (repetition? adverse events?)
or any of the other usual parameters of a power calculation. This is
important as the study essentially showed no difference between the
different interventions and it is essential to know if the study was big
enough to stand a good chance of detecting a difference.
Next is the issue of the representativeness of the study sample. Only
about one in five of eligible patients were recruited. Were they different
in any important ways, apart from age, from those who were not recruited?
I also note that nearly a quarter of patients who were contacted in the
intervention groups had a DSM IV diagnosis of somatisation disorder - a
remarkably large number which if true would make this a very unusual
Then there are the results. It is unclear as to how many people had
reattempted suicide - in table 2, 103 people report reattempting yet in
the text the numbers add up to 91. Why the discrepancy? Also we are not
told how many episodes occured in each group which may be important as the
study may have had an effect on this outcome. In the analysis of those who
were contactable there is no significant difference between the three
groups using a chi-squared test with two degrees of freedom. However
comparing the individual groups with each other there is a statistically
significant difference between those who received a telephone call at one
month and controls but no difference between the two telephone groups or
between the telephone call at three months and the control group.
So how to make sense of these results? Probably telephoning people at
a month after they have self poisoned doesn't make much difference to
repetition compared to treatment as usual. Any differences observed are
probably due to confounding factors, for example people who are easy to
contact by phone probably have more resources and are more stable (both
geographically and emotionally) than those who cannot be contacted so are
less likely to self-harm.
The lesson for clinical practice is that when people who self harm
are seen in the general hospital, clinicians should be assiduous in
getting at least three telephone numbers and two addresses from them. This
should help in avoiding the one in four people lost to follow-up found in
Competing interests: No competing interests