It has been established that people who have attempted suicide are far more
likely to complete it in future attempts than are those with no prior
attempts. Now new research shows that coexisting schizophrenia or a mood
disorder substantially increases the mortality in this population.
In a cohort of nearly 40,000 Swedish residents who had been hospitalized
for attempted suicide between 1973 and 1982, researchers found that the
likelihood of subsequent death from suicide among these individuals through
2003 was the highest in men and women with a concurrent diagnosis of
schizophrenia (see graph). Compared with the suicide rates of the reference
group, the suicide rates for men were 4.1 times higher and for women, 3.5
times higher. The reference group was composed of hospitalized attempters who
had not received a psychiatric diagnosis within one year of the event.
The second highest risk group in this population was composed of those with
a coexisting diagnosis of bipolar or unipolar disorder (with an
International Classification of Disease [ICD] code of 296.1-296.9).
Their risks of dying of suicide in the follow-up period were 3.5 times and 2.5
times the rates of the reference group in men and women, respectively.
A coexisting psychiatric disorder was defined as having a diagnosis from
the following list concurrent with the hospitalization for suicide attempt or
within one week after the attempt-related hospitalization: bipolar and
unipolar disorders, other depressive disorders (ICD codes 296.0 and
300.4), schizophrenia, anxiety disorder, adjustment disorder or posttraumatic
stress disorder (PTSD), alcohol abuse or dependence, drug abuse or dependence,
and personality disorder. Those with other psychiatric diagnoses were excluded
for the study cohort.
The most dangerous period appeared to be the first year after the
hospitalization for suicide attempt, the study found. A large proportion of
all the completed suicides in the overall follow-up period occurred within the
first year of the attempt regardless of the psychiatric diagnosis, including
the reference group.
Of the approximately 27,000 people in the reference group, about 11 percent
of the men and 7 percent of the women eventually died of suicide in the 21 to
31 years of follow-up. In comparison, approximately 39 percent of the male
attempters with schizophrenia eventually died of suicide in the same period,
and more than half of these deaths occurred within one year after the attempt.
Almost a quarter of the female attempters with schizophrenia died of suicide,
more than half in the first year. A similar pattern was seen in attempters
with bipolar and unipolar
disorders.
Most other categories of psychiatric disorders were also associated with
statistically significantly higher risks of eventual suicide during the
follow-up period, except for adjustment disorder or PTSD in men and women and
alcohol abuse or dependence in men.
Past studies documented a rate of completed suicide as high as 13 percent
in people with past attempts, depending on the length of follow-up, the
authors noted. Because it is difficult to identify people most likely to die
from suicide within the general population, more aggressive interventions for
those with past attempts and concurrent schizophrenia as well as mood
disorders, while also considering the time frame after the previous attempt,
can help mental health professionals better target high-risk patients and more
effectively prevent suicide, they suggested.
The study authors used data on Swedish citizens in the national registry
for hospital care in 1973-1982 and traced individuals in the national
cause-of-death register, which contains information on more than 99 percent of
Swedish residents, including deaths that occurred outside Sweden. The authors
also adjusted for age, educational levels, and immigrant status as possible
confounders in their analyses.
The study was published in BMJ online on November 18, 2008, and
funded by the Stockholm County Council, the Karolinska Institute, which
employed the authors, and the Swedish Prison and Probation Service.