Risk factors for suicide in schizophrenia: Findings from a Swedish population-based case-control study

https://doi.org/10.1016/j.schres.2008.12.023Get rights and content

Abstract

Previous reports regarding risk factors for suicide in schizophrenia have been inconclusive. We performed a matched case-control study of in-patient-treated schizophrenia patients in order to assess the suicide risk associated with socioeconomic, demographic, and psychiatric factors.

The cases were 84 patients who died by suicide within five years after diagnosis in a cohort of all patients discharged for the first time from psychiatric hospitals in Stockholm County, Sweden, with a diagnosis of schizophrenia, schizophreniform disorder or schizoaffective disorder between the years 1984 and 2000. One control was individually and randomly matched with each case from the same cohort by date (± 1 year) and age (± 5 years) at index diagnosis. Data were retrieved from clinical records of the case-control pairs in a blind fashion.

Of the suicides, 54% were men and 46% were women. In multivariate analyses, higher educational attainment (odds ratio [OR] 3.0, 95% confidence interval [CI] 1.03–8.0), age ≥ 30 years at onset of symptoms (OR 4.8, CI 1.1–21.2), and a history of a suicide attempt requiring non-psychiatric medical treatment (OR 5.0, CI 1.6–15.4) were found to be significantly associated with an increased suicide risk. Gender did not significantly affect the suicide risk, nor did a history of self-discharge, compulsory in-patient treatment, substance-use disorder or a family history of mental disorders or suicide.

In schizophrenia, certain suicide risk factors may differ from those in the general population. Clinical suicide risk assessment for schizophrenia patients should be performed taking this into account.

Introduction

Schizophrenia is a serious mental disorder with life-time prevalence estimates of about 0.4% to 0.5% (Goldner et al., 2002, Saha et al., 2005). Mortality is two- to threefold higher in schizophrenia patients than in the general population (McGrath et al., 2008), suicide being one of the main causes of excess death (Ösby et al., 2000). In recent meta-analyses, the risk of suicide in schizophrenia was found to be 13 times greater than in the general population (Saha et al., 2007), and the life-time risk of suicide in schizophrenia was estimated to be 4.9% (Palmer et al., 2005).

A meta-analysis reported that the suicide risk in schizophrenia is robustly associated with previous depressive disorder, hopelessness, history of suicide attempt, and poor adherence to treatment (Hawton et al., 2005). However, although some studies have also reported that the suicide risk in schizophrenia is associated with male gender (Breier and Astrachan, 1984), higher educational attainment (Drake et al., 1984), substance use disorders (Pompili et al., 2007), and a family history of suicide (De Hert et al., 2001), the findings regarding these and a number of other factors have been inconclusive (Hawton et al., 2005). Moreover, although the suicide risk is known to be greatest early in the time period following the first diagnosis of the disorder (Palmer et al., 2005), data are inconclusive as to how the age at onset of symptoms affects the suicide risk (Hawton et al., 2005). Previous studies in this field have been relatively small, not population-based, and limited by a lack of adjustment for potential confounders. We performed a population-based matched case-control study to assess clinical and demographic risk factors for suicide, selecting as cases 84 consecutive in-patients diagnosed with schizophrenia for the first time in Stockholm County, Sweden, who died from suicide within five years from the index diagnosis, and as controls the same number of living schizophrenia patients from the same population matched by date and age at index diagnosis.

Section snippets

Study subjects

The National Patient Register contains individual-based information on in-patient treatment with complete coverage of psychiatric hospitals in Stockholm County since 1973. For each hospitalization, the register includes the patient's unique civic registration number, dates of admission and discharge, diagnoses at discharge, psychiatric department, and hospital. It is compulsory for all in-patient facilities to submit data on discharge and the register is therefore population-based.

We defined a

Results

Patients who died by suicide (cases) and matched controls were similar regarding the matching criteria (Table 1). Both groups had a mean age of 32.8 (SD 9.7) years and a median age of 29 (range 18–64) years at diagnosis. The suicides occurred between 1987 and 2000 at a mean age of 34.1 years (SD 9.8) and a median age of 31 (range 18–65) years. Suicide by ‘jumping’ and ‘other method’ (including jumping in front of a vehicle) were more frequent than in the general population, while poison was

Discussion

The main findings of this study were that higher educational attainment, age ≥ 30 years at onset of symptoms and a history of a suicide attempt were associated with an increased risk of suicide within five years after a first clinical schizophrenia in-patient diagnosis. There were also tendencies for an increased risk of suicide being associated with having been married or cohabiting, and with a longer total duration of hospitalization. Gender did not significantly affect the suicide risk, nor

Role of the funding source

This study was supported by grants from Stockholm County Council, Gävle County Hospital, Stiftelsen Söderström Königska Sjukhemmet, Psykiatrifonden, and Bror Gadelius stiftelse. Erik Jönsson was supported by the Swedish Research Council (K2007-62X-15078-04-3, K2008-62P-20597-01-3). The funding agencies played no role in the design, data acquisition, analysis, or interpretation of the results.

Contributors

Johan Reutfors, M.D. was responsible for collecting the data; managed the literature review and searches; designed the study protocol; and wrote the first draft of the report. He also participated in the development of the study design, the statistical analyses and the interpretation of data. Lena Brandt, M.Sc. was responsible for the statistical analyses; assisted in the development of the study design, interpretation of data and writing the report. Erik G. Jönsson, M.D., Ph.D. assisted in

Conflict of interest

UÖ has received grant/research support from Bristol-Myers Squibb and Janssen-Cilag; has been a consultant for AstraZeneca, Bristol-Myers Squibb, Ely Lilly, and Pfizer; has been reimbursed by Bristol-Myers Squibb, Ely Lilly, and Pfizer for attending conferences; has received fees for speaking from Bristol-Myers Squibb, Ely Lilly, Organon, and Pfizer. Nothing has been reported by the other authors.

Acknowledgement

We thank Marianne Ask for invaluable assistance in the handling of the clinical records.

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