BMJ  2004;329:261 (31 July), doi:10.1136/bmj.38133.622488.63 (published 22 June 2004)

Paper

Change in suicide rates for patients with schizophrenia in Denmark, 1981-97: nested case-control study

¹ Bispebjerg Hospital, Department of Psychiatry, Bispebjerg Bakke 23, 2400 Copenhagen NV, Denmark, ² National Centre for Register-based Research, University of Aarhus, Taasingegade 1, DK-8200 Aarhus N, Denmark

Abstract

Objective To study the change in risk of suicide among patients with schizophrenia and related disorders.

Design Nested case-control design with linked data.

Setting Four longitudinal Danish registers.

Participants 18 744 people aged up to 75 years who committed suicide in 1981-97 individually matched with 20 controls.

Results Over the time studied the reduction in suicide rate among patients with schizophrenia and schizophrenia spectrum disorder was similar to that seen in the general population (incidence rate ratio 1.00, 95% confidence interval 0.98 to 1.03). The reduction among patients with other psychosis in the schizophrenia spectrum was faster than the reduction seen in the general population. Among people admitted to hospital with schizophrenia the risk of suicide was highest in the first year after first admission, and the excess risk was largest in the younger age groups—that is, the risk decreased per year for every additional year of age.

Conclusion The suicide rate among patients with a diagnosis of schizophrenia and related disorders has fallen. This may be due to better psychiatric treatment, reduced access to means of suicide, or improvements in treatment after suicide attempts.

Introduction

In 1980, the suicide rate in Denmark peaked and reached a level that was among the highest in the world, with 34 suicides per 100 000 inhabitants. After 1980 the number of suicides decreased each year, and in 1997 the rate was 15 per 100 000 inhabitants, a 56% reduction.

In Denmark, about half of the people who commit suicide have previously been admitted to psychiatric departments and more than a quarter have been admitted during the past year.^{1 2} It is consistently reported from several countries that the age and sex standardised mortality for suicide in people with schizophrenia is high.^{3 4} In a meta-analysis the lifetime risk of suicide among patients after a first admission for schizophrenia was 5.6%.⁵ Danish and Swedish analyses have shown an increasing rate of suicide among women with a diagnosis of schizophrenia, while the suicide rate has declined in the general population.^6-8

We investigated the suicide rates among patients with schizophrenia and related disorders to see if there was a similar reduction to that seen in the general suicide rate in Denmark from 1981 to 1997. We hypothesised that the ratio between suicide rates in people with a diagnosis of schizophrenia and related disorders compared with suicide rates in the general population would increase.

Methods

Study population—Data for this study were taken from four Danish longitudinal registers (see bmj.com). From the cause of death register we extracted a list of all people aged less than 76 years who committed suicide in Denmark from 1981 to 1997. By using a nested case-control design matching for birth year, sex, and calendar time, we randomly selected 20 controls per case from a 5% random sample of the total population in the database. We included 18 744 people who committed suicide and 374 880 population controls in the study.

Diagnostic groups and psychiatric treatment—We extracted information about psychiatric inpatient treatment from the Danish psychiatric case register. Patients were subdivided into mutually exclusive diagnostic groups on the basis of the diagnosis at the latest admission ("schizophrenia," "other psychosis in schizophrenia spectrum," and "schizophrenia spectrum disorders").

Data analyses—We used conditional logistic regression. Because of the method of sampling controls from people at risk at the time, odds ratio can be interpreted as incidence rate ratios.⁹ Of particular interest was the change in the suicide rate over the calendar period. Exposure to inpatient treatment for schizophrenia and related disorders were considered as explanatory variables. We adjusted the incidence rate ratios for suicide for social and demographic risk factors of suicide in the general population—that is, education, place of residence, income, cohabitation, employment status, place of birth, number of children, and death and suicide of a child.

Results

The crude suicide rates in the general population fell from 1981 to 1997 (fig 1). Among those who had been admitted to psychiatric hospitals or departments in the same period, there were 756 suicides among patients with schizophrenia, 633 suicides among patients with other psychosis within the schizophrenia spectrum, and 276 suicides among patients with non-psychotic schizophrenia spectrum disorder. Figure 2 shows the incidence rate ratios for suicide, adjusted for age and sex, for patients with these diagnoses.

View larger version (26K): [in this window] [in a new window]   Fig 1 Number of suicides per 100 000 inhabitants in Denmark, 1981-97

 

View larger version (35K): [in this window] [in a new window]   Fig 2 Incidence rate ratio for suicide in patients with schizophrenia and related disorders, relative to general population. Adjusted for age and sex

 

We adjusted the incidence rate ratio for suicide for social and demographic risk factors and for time since admission and included age as an interaction term. We then fitted a regression line expressing the change from 1981 to 1997 relative to the general population, adjusted for confounding factors. For all diagnostic groups there was a linear trend (P = 0.14). As in the non-adjusted analyses (see bmj.com) we found that for patients with schizophrenia and non-psychotic schizophrenia spectrum disorder the decrease was similar to the decrease in the general population, while the decrease for patients with other psychosis in schizophrenia spectrum was faster; this change was explained by a faster reduction in suicide rate among male patients with these diagnoses compared with the general population.

The risk of suicide was high in all diagnostic groups during an inpatient stay and during the first month after discharge, and the longer the time a patient had been discharged, the lower the risk of suicide (table). Patients who were admitted for the first time during the previous year had a 59% higher risk of suicide compared with other patients.

View this table: [in this window] [in a new window]   Incidence rate ratio for suicide among patients with schizophrenia and related disorders, adjusted for social and demographic risk factors* and for interaction with age by diagnosis, compared with the general population. Figures are incidence rate ratios (95% confidence intervals)

 

For patients with schizophrenia, the excess suicide mortality (relative to the general population) decreased with increasing age. Adjustment for social and demographic risk factors reduced the incidence rate ratio for suicide among patients with schizophrenia from 21.37 to 12.26. Thus, social and demographic factors explain some of the increased suicide risk for schizophrenia.

In the general population the suicide rate among men is about twice as high as in women. The incidence rate ratio of suicide for women with schizophrenia and related disorders is higher than for men for all diagnostic groups and for all phases of treatment. This does not mean that the suicide rate for female patients is higher than for male patients, but it indicates a weaker effect of schizophrenia and related disorders among men. For both sexes, the decrease is similar to the decrease in the general population, except that men with other psychosis in the schizophrenia spectrum had a faster decrease in suicide rate than men in the general population.

Discussion

Explanations for findings
We cannot draw any firm conclusions regarding our observations of a decreasing risk of suicide over time. One hypothesis is that the patients were exposed to the same positive factors as the general population, such as reduced availability of means to commit suicide, better somatic and psychiatric treatment after attempted suicide, increased social and cultural stability in society, more general focus on prevention, and increased access to telephone counselling and psychiatric emergency services.¹⁰

Another hypothesis is that the suicide rates among the patients fell at the same rate but through different mechanisms. The results must be compared with the transition in the organisation of psychiatric treatment, with a marked reduction in the number of psychiatric beds and more focus on outpatient treatment and social support. In 1980, the number of psychiatric beds in Denmark was 2.0 per 100 000 inhabitants, and during the years until 1997 the number was reduced to 0.79 per 100 000,¹¹ a reduction of 6000 beds (Denmark had a population of 5.2 million inhabitants in 1997). During the same period the number of supported housing places (previously psychiatric nursing homes) increased from none in 1980 (at that time defined as psychiatric beds) to 3533 in 1997.¹¹ In addition, before 1997, 1728 places were established in psychiatric group homes with staff support. Thus, the net reduction in the number of psychiatric beds and supported housing in the community between 1980 and 1997 was less than 1000 (a reduction of 0.19 beds per 100 000 inhabitants). During the same period, there was an increase in the number of people employed in psychiatry. The number of staff members employed in community mental health centres doubled between 1993 and 1997. In psychiatric wards, the number of staff members increased by 30%. Furthermore, staff members were employed with the task of supporting people with severe mental illness in their own home.¹¹ Thus the treatment and social support available for patients with schizophrenia and related disorders has increased, providing more possibilities for closer follow up during outpatient periods and closer observation and support during inpatient stay.

In the general population, the decline in suicide rate was more marked for female patients with schizophrenia than for male patients. This suggests that the decline in risk of suicide in patients was due to some of the same mechanisms as in the general population, such as less availability of means to commit suicide. If the decline in suicide rate among the patients was mainly due to better treatment of schizophrenia and related disorders, it would probably be equally effective in male and female patients.

What is already known on this topic The suicide rates in the general population in Denmark fell by 56% during the period from 1980 to 1997 Previous studies have raised concern about whether the reduction in number of psychiatric beds was associated with an increased risk of suicide among patients with schizophrenia The risk of suicide is highest the first year after first admission for schizophrenia, and the excess risk is highest in the younger age groups What this study adds The reduction in suicide rates among patients with schizophrenia was similar to the reduction among the general population This may have been facilitated by better psychiatric treatment or by factors that such patients share with the general population, such as less access to means to commit suicide and better treatment after attempted suicide The risk of suicide among patients with schizophrenia is almost constantly 20 times higher than seen in the general population

Conclusion
Throughout the period 1981-97, the risk of suicide among patients with schizophrenia was much higher than in the general population. The suicide rate among patients with schizophrenia and related disorders declined from 1981 to 1997, as did the suicide rate in the general population. It is unclear whether the reason for the reduction in suicide risk among patients with schizophrenia and related disorders is due to factors affecting the general population—such as decreased availability of means to commit suicide—or to factors that affect only patients with schizophrenia and related disorders—such as changes in psychiatric services—or both. Priority must continuously be given to preventive efforts directed towards the general population as well as towards psychiatric patients. The finding that the risk of suicide is especially high during the first month after discharge should lead to systematic evaluation of risk among inpatients before discharge and increased treatment and support immediately after discharge. Younger patients experiencing a first episode of schizophrenia are at high risk for suicide, and more intensive treatment and support should be offered to them.

---

This is the abridged version of an article that was posted on bmj.com on 22 June 2004: http://bmj.com/cgi/doi/10.1136/bmj.38133.622488.63

Contributors: See bmj.com

Funding: Stanley Medical Research Institute and the Danish Medical Research Council, Ref No 22-02-0402. The National Centre for Register-based Research was supported by the Danish National Research Foundation.

Competing interests: None declared.

Ethical approval: This study was approved by Danish Data Protection Agency (2000-41-0307).

References

1. Mortensen PB, Agerbo E, Erikson T, Qin P, Westergaard-Nielsen N. Psychiatric illness and risk factors for suicide in Denmark. Lancet 2000;355: 9-12.[CrossRef][ISI][Medline]
2. Qin P, Agerbo E, Mortensen PB. Suicide risk in relation to socioeconomic, demographic, psychiatric, and familial factors: a national register-based study of all suicides in Denmark, 1981-1997. Am J Psychiatry 2003;160: 765-72.[Abstract/Free Full Text]
3. De Hert M, Peuskens J. Psychiatric aspects of suicidal behaviour. In: Hawton K, Van Heeringen K, eds. The international handbook of suicide and attempted suicide. Chistester: Wiley, 2000: 121-34.
4. Black DW, Warrack G, Winokur G. The Iowa record-linkage study. Arch Gen Psychiatry 1985;42: 71-5.[Abstract]
5. Palmer BA, Pankratz VS, Bostwicj JM. The lifetime risk of suicide in schizophrenia: a reexamination. Am J Psychiatry (in press).
6. Mortensen PB, Juel K. Mortality and causes of death in first admitted schizophrenic patients. Br J Psychiatry 1993;163: 183-9.[Abstract/Free Full Text]
7. Osby U, Correia N, Brandt L, Ekbom A, Sparen P. Time trends in schizophrenia mortality in Stockholm county, Sweden: cohort study. BMJ 2000;321: 483-4.[Free Full Text]
8. Rossau CD, Mortensen PB. Risk factors for suicide in patients with schizophrenia: nested case-control study. Br J Psychiatry 1997;171: 355-9.[Abstract/Free Full Text]
9. Clayton D, Hills M. Statistical models in epidemiology. Oxford: Oxford University Press, 1993.
10. Sundhedsstyrelsen (Danish National Board of Health). Forslag til national handlingsplan for forebyggelse af selvmord og selvmordsforsøg i Danmark. [National Programme for Prevention of Suicide and Suicide attempt.] 1st ed. Copenhagen: Sundhedsstyrelsen, 1998.
11. Ministry of Social Affairs MotIaH. Government status report on services for the mentally ill 2000. Copenhagen: Statens Information, 2002.

(Accepted 6 May 2004)

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

Relevant Articles

Managing the acute psychotic episode

Peter Byrne
BMJ 2007 334: 686-692. [Extract] [Full Text] [PDF]

A randomised multicentre trial of integrated versus standard treatment for patients with a first episode of psychotic illness

Lone Petersen, Pia Jeppesen, Anne Thorup, Maj-Britt Abel, Johan Øhlenschlæger, Torben Østergaard Christensen, Gertrud Krarup, Per Jørgensen, and Merete Nordentoft
BMJ 2005 331: 602. [Abstract] [Full Text] [PDF]

Suicide rates in people with schizophrenia have declined
BMJ 2004 329: 0. [Full Text]

Related external webpages:

Paper plus

This article has been cited by other articles:

• BERTELSEN, M., JEPPESEN, P., PETERSEN, L., THORUP, A., OHLENSCHLAeGER, J., QUACH, P. L., CHRISTENSEN, T. O., KRARUP, G., JORGENSEN, P., NORDENTOFT, M. (2007). Suicidal behaviour and mortality in first-episode psychosis: the OPUS trial. Br. J. Psychiatry 191: s140-s146 [Abstract] [Full text]  
• Byrne, P. (2007). Managing the acute psychotic episode. BMJ 334: 686-692 [Full text]  
• Pirkola, S., Sohlman, B., Heila, H., Wahlbeck, K. (2007). Reductions in Postdischarge Suicide After Deinstitutionalization and Decentralization: A Nationwide Register Study in Finland. Psychiatr. Serv. 58: 221-226 [Abstract] [Full text]  
• Melle, I., Johannesen, J. O., Friis, S., Haahr, U., Joa, I., Larsen, T. K., Opjordsmoen, S., Rund, B. R., Simonsen, E., Vaglum, P., McGlashan, T. (2006). Early Detection of the First Episode of Schizophrenia and Suicidal Behavior. Am. J. Psychiatry 163: 800-804 [Abstract] [Full text]  
• Petersen, L., Jeppesen, P., Thorup, A., Abel, M.-B., Ohlenschlaeger, J., Christensen, T. O., Krarup, G., Jorgensen, P., Nordentoft, M. (2005). A randomised multicentre trial of integrated versus standard treatment for patients with a first episode of psychotic illness. BMJ 331: 602- [Abstract] [Full text]  

Rapid Responses:

Read all Rapid Responses

Availability of means to commit suicide

gopal s chinnari, et al.
bmj.com, 29 Jun 2004 [Full text]

Good news for mental health - pity psychiatry had nothing to do with it.

Woody Caan
bmj.com, 30 Jun 2004 [Full text]

Let's have more !

A.A.W. Amarasinghe, MD,
bmj.com, 1 Aug 2004 [Full text]

Is it mainly due to common factors?

Lena K Palaniyappan
bmj.com, 1 Aug 2004 [Full text]

Suicide and schizophrenia: role of depression and stigma!

Dr. Naseem A. Qureshi, MD, IMAPA, LMIPS
bmj.com, 3 Aug 2004 [Full text]

The role of misdagnosis

Andrew Al-Adwani
bmj.com, 4 Aug 2004 [Full text]

Suicide in psychiatric patients

Dermot Walsh
bmj.com, 10 Aug 2004 [Full text]