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Schizophrenia and suicide

Suicide risk in schizophrenia [1]
Results
Risk factors for suicide in schizophrenia [2]
Results
Comment

Schizophrenia is associated with a significant risk of suicide. Two systematic reviews provide an insight into the level of risk, and into the risk factors involved.

Suicide risk in schizophrenia [1]

A systematic review used a literature search for articles observing cohorts of schizophrenic patients with at least two years of observation and at least 90% follow up. Searching involved two electronic databases (one a specialist psychiatric database), plus extensive bibliographic and reference reviews over 90 years. Studies selected used diagnostic criteria of their times for schizophrenia.

From each of about 60 studies information was collected on number of patients, deaths, suicides, and length of follow up.

Results

Twenty-nine cohorts observed schizophrenics from date of admission or illness onset, and another 32 were composed of any type of patient. The studies were as small as a few tens of patients, to over 9,000. Most involved several hundred patients, followed up for two to 22 years.

For those studies that examined patients from first admission or new onset (22,598 patients), the case fatality estimate (percentage of original sample who died by suicide) was 2.9% (95% CI 4.3 to 5.6%). Of all deaths, 31% were deaths by suicide. Among studies using mixed samples (25,578 patients), the case fatality estimate was 2.3% (1.5 to 3.5%) and 6% of the all deaths was by suicide.

Analysis according to time of follow up suggested that suicide risk was greater sooner rather than later after diagnosis or onset. The estimate of lifetime suicide prevalence in those observed from first admission or illness onset was 5.6% (95% confidence interval, 3.7% to 8.5%). Mixed samples showed a rate of 1.8% (95%CI, 1.4% to 2.3%). Case fatality rates showed no significant differences when studies of patients diagnosed with the use of newer criteria were compared with studies of patients diagnosed under older criteria.

Risk factors for suicide in schizophrenia [2]

A second systematic review used a broad search strategy to select studies with information about risk factors for schizophrenia. For inclusion, studies were required to have a patient diagnosis of schizophrenia and related disorders, have more than 90% of patients aged over 16 years, be cohort studies with a minimum follow up period of one year, or be a case-control study, investigating specific risk factors.

These risk factors included sociodemographic information, family history (particularly of psychiatric disorders, depression, suicide or alcohol misuse), personal history (broken home, parental loss, education, IQ, recent loss), and clinical history. The clinical history factors were widely drawn, and included factors like psychiatric symptoms (depression, fear of mental disintegration), suicide ideation, previous suicide attempts, and many others.

Results

In all, 29 studies were included, three prospective cohorts, two retrospective cohorts, three nested case control studies, fourteen case control studies with similar controls, and seven case control studies with different or unclear controls. In total, there were 1675 suicides (average 58 per study, median 33) and 11,303 controls (average 390 per study, median 69). Most of the studies specified a diagnostic criterion for schizophrenia.

The nature of the controls chosen varied widely. Some were randomly selected inpatients or outpatients from the same institution, some were surviving patients from the same cohort from whom the suicide cases were taken, or selected from non-suicide inpatients, or patients with a high risk of suicide.

A number of risk factors were not associated more often with suicide cases than controls (Table 1), or associated statistically, but not robustly because of the small number of studies and patients. A number of other factors were robustly associated with suicide, either because there were larger numbers of studies and patients, or because there was a large effect with moderate numbers of studies and patients (Table 2). An example of consistency between studies relating past attempts of suicide is shown in Figure 1.



Table 1: Factors with limited or no association with suicide in schizophrenia



Factor with limited association with suicide
Male gender Worthlessness
Living alone Hopelessness
Not living with family Impulsivity
Family history of depression
Factor not associated with suicide
Ethnicity Violence
Married Physical illness
Divorced Alcohol misuse
Single Negative symptoms
Having children Social withdrawal
Employed Sleep disturbance
Unemployed Insight
Broken home Delusions
Limited education Hallucinations: command
Higher education Compulsory admission
Living with family Recent suicide threat
Family history of suicide Positive symptoms
Family history of psychiatric disorder
Family history of alcohol misuse
Substance misuse or dependence




Table 2: Factors associated with successful suicide in patients with schizophrenia



Risk factor
Number of
Risk factor (%) in
Relative risk
(95% CI)
Odds ratio
(95% CI)
Trials
Patients
Events
Cases
Controls
Recent suicide ideation
4
486
142
52
4
12 (6.3 to 23)
30 (12 to 73)
Fear of mental disintegration
4
362
55
33
4
5.9 (3.1 to 11)
12 (1.8 to 81)
Drug misuse or dependence
4
3385
240
22
6
2.6 (1.8 to 3.9)
3.2 (2.0 to 5.2)
Recent depression
7
653
178
42
16
2.3 (1.8 to 3.0)
6.2 (1.3 to 30)
Recent loss
3
317
110
43
31
2.3 (1.6 to 3.2)
4.0 (1.4 to 12)
History of suicide attempt
22
6849
1952
53
25
2.2 (2.0 to 2.4)
4.1 (2.8 to 6.0)
Past depression
9
2336
599
44
21
2.2 (1.8 to 2.7)
3.0 (2.1 to 4.5)
Poor compliance with treatment
4
363
122
54
20
2.0 (1.5 to 2.7)
3.8 (2.2 to 6.4)
Past ideation
4
1532
339
52
19
1.7 (1.4 to 2.1
3.3 (1.8 to 6.4)
Agitation or motor restlessness
4
1470
284
50
17
1.3 (1.04 to 1.7)
2.6 (1.5 to 4.4)
Hallucination
6
2133
961
32
47
0.7 (0.6 to 0.8)
0.5 (0.4 to 0.7)




Figure 1: Previous suicide attempts in schizophrenic patients committing suicide, and controls





Recent suicide ideation, fear of mental disintegration, drug misuse or dependence, recent depression, recent loss, poor compliance with treatment, and history of suicide attempt all occurred much more often with suicide cases than with controls (Table 2, which has odds ratios from the paper as well as the more useful relative risk). Hallucination was the only factor that occurred less frequently.

Comment

About 1 in 20 schizophrenics will commit suicide during their lifetimes, more often near illness onset. The findings of the meta-analysis do seem to be borne out by other studies published since the meta-analysis was completed. For instance, there were 78 completed suicides in 4237 acute inpatients with schizophrenia admitted between 1985 and 2000 in Taiwan [3]. That is a rate of 2%, and half of the suicides occurred within four years of first admission, but Taiwan may well have lower rates of some important risk factors, particularly drug misuse. Rates of suicide in mainland China [4] in the late 1990s averaged 0.7% of the schizophrenic population annually (28,737 suicides in people with schizophrenia out of 4.25 million people with schizophrenia in China). If half of the suicides were in the first few years, that would equate to a lifetime risk of almost 6%. These two large studies in east Asia confirm the overall estimate of between 2% and 5% lifetime risk of death by suicide.

A number of factors, particularly recent suicide ideation, fear of the impact of the illness on mental functioning, and depression, are positively associated with increased risk of suicide in patients who have schizophrenia. The nature of the disorder seems less important. Active treatment of affective symptoms, improving adherence to treatment, and maintaining vigilance in patients with risk factors may contribute to reducing actual suicides in patients with schizophrenia. These are two important systematic reviews.

The interesting thing about the mainland China study of suicide [4] was that it examined suicide by schizophrenic patients as a percentage of all suicides. Ten percent of all suicides were suicides by schizophrenic patients. This implies that recognising suicidal risk factors in patients with schizophrenia should be a major factor in reducing deaths from suicide.

References:

  1. BA Palmer et al. The lifetime risk of suicide in schizophrenia. Archives of General Psychiatry 2005 62: 247-252.
  2. K Hawton et al. Schizophrenia and suicide: systematic review of risk factors. British Journal of Psychiatry 2005 187: 9-20.
  3. CJ Kuo et al. Risk factors for completed suicide in schizophrenia. Journal of Clinical Psychiatry 2005 66: 579-585.
  4. MR Phillips et al. Suicide and the unique prevalence pattern of schizophrenia in mainland China: a retrospective observational study. Lancet 2004 364: 1062-1068.

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