Period trends in rate of suicide in first 28 days after discharge from psychiatric hospital in Scotland, 1968-92

Introduction

The risk of suicide in patients in the year after discharge from psychiatric hospital is highest in the first 28 days.1 2 3 4 Suicide soon after discharge may be related to the nature and quality of aftercare.1 Focusing preventive efforts on the period soon after discharge may be one way of contributing to the Health of the Nation's target of a 33% reduction in suicide among people with sever mental disorder by the year 2000, from 15% to 10%.5 6 Assuming that service provision affects the risk of suicide, past changes in service provision might also have done so. In particular, the mental health services in the United Kingdom have changed profoundly over the past three decades, from being a predominantly institutional form of care to being an increasingly community based form. These changes have been associated with an important reduction in the number of psychiatric beds.7 There has been concern that the change to community based care may be associated with a higher rate of suicide soon after discharge.8 9 We investigated the possibility of period trends in the rates of suicide soon after discharge by studying a cohort of patients discharged from psychiatric hospitals in Scotland during 1968 and 1992.

Patients and methods

Results

In all, 159742 male patients and 178271 female patients were discharged from Scottish psychiatric hospitals at least once during 1968 to 1992. There were 196 suicides within 28 days of discharge in 20520 person years at risk in male patients and 171 suicides in 24114 person years at risk in female patients. The crude suicide rate per 100000 person years at risk was 955 (95% confidence interval 831 to 1099) in male patients and 709 (611 to 823) in female patients. The crude standardised mortality ratio was 43 (37 to 50) in male patients and 59 (51 to 69) in female patients. Tables I and II show the observed number of suicides, person years at risk, suicide rate per 100000 person years at risk, and standardised mortality ratio by sex, age group, and period and by diagnosis and sex respectively. The standardised mortality ratios in the first 28 days were highest in patients with discharge diagnoses of non-psychotic depression and personality disorder and in female patients with non-depressive neuroses.

During 1968 to 1992 the age specific suicide rates in the Scottish population per 100000 population steadily increased in male patients, especially in those aged under 45 years (fig 1). In female patients the age specific rates have converged somewhat, with the most pronounced change being a fall in the rates in older age groups (fig 2). Table III shows the standardised mortality ratio for each period, adjusted for diagnosis and age, estimated from the regression models. The deviances of the models were close to the degrees of freedom in both sexes, suggesting a reasonable fit of the model to the data (table III).

FIG 1

Suicide rates in male population in Scotland, 1968-92 (9974 suicides)

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FIG 2

Suicide rates in male population in Scotland, 1968-92 (9974 suicides)

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The linear trend in period effect on externally standardised mortality ratios was significant in both sexes: in male patients there was a decrease in the mortality ratio (P=0.008) and in female patients an increase (P=0.0001). The standardised mortality ratio in male patients was 38% lower in the last five years than in the first five (standardised mortality ratio 0.62 (0.39 to 0.98)) while that in female patients discharged in the last five years was almost three times that in the first five (2.73 (1.64 to 4.56)).

In female patients the trend in period effect was also evident in the study cohort (P=0.013), and so the effect is probably not accounted for by the reduction in suicide rates in the female general population. In contrast, no trend in period effect was evident in the male cohort (P=0.17). This implies that suicide rates within 28 days of discharge remained relatively stable despite a substantial increase in the suicide rates in the male genera1 population. As figure 3 shows, the numbers of readmissions increased steadily between 1970 and 1990, while the numbers of first admissions declined, with an increase in the total number of admissions. The number of available, staffed, nongeriatric psychiatric beds in Scotland decreased from 16589 in 1976 to 6456 in 1992 (61%; figures are not available for before 1976). The median length of stay for voluntary patients in 1968 was five weeks for male patients and six weeks for female patients and in 1992 was two weeks and three weeks respectively. This shows that a shift has occurred towards shorter stays and more readmissions.

FIG 3

—Five year moving average of admissions of patients aged 15-84 to psychiatric hospital in Scotland, 1969-92. Estimated average annual change (95% confidence interval) in (a) first admissions: 1.3% (−1.6% to −1.0%) (male patients), −1.7% (−1.9% to −1.5%) (female patients); (b) readmissions: 2.2% (1.7% to 2.7%) (male patients), 2.5% (2.1% to 2.8%) (female patients); (c) total admissions: 0.8% (0.5% to 1.1%) (male patients), 0.8% (0.7% to 1.0%) (female patients)

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Discussion

We have identified period trends in the rate of suicide soon after discharge in patients aged 15-84 discharged from psychiatric hospital in Scotland during 1968 to 1992, with unexpected sex differences. In female patients the suicide rate increased progressively in the cohort, and, after the suicide rates in the general Scottish population were adjusted for, the rate almost trebled between the first and last five year periods. In male patients no period trend occurred in the cohort, and after adjustment the suicide rates fell by approximately 40%.

The study's design does not allow direct inferences about the causation of the observed trends, and interpretation must therefore be cautious. Furthermore, misclassification of discharge diagnosis and the distinction between first admission and readmission have been reported in the routinely collected dataset used in this study.20 21 The definition of suicide used may have introduced misclassification, although we followed recognised practice by using codes E950-9 and E980-9.12 The advantage of using national data is that they provided sufficient power to use a rare event as the outcome.

The increase in the rate of suicide soon after discharge in female patients may be related to the change in service provision over the period. Discharge at an earlier stage of recovery may exacerbate feelings of loneliness and hopelessness and increase the risk of suicide.1 9 10 Previous studies have found that patients who commit suicide have had shorter stays, more commonly have non-psychotic diagnoses, and have communicated more feelings of loneliness.9 22 23 24 Female schizophrenic patients who commit suicide are more likely to be single and live alone.23 Although we could not directly examine the effect of shorter inpatient stays on the risk of suicide soon after discharge, our findings would be consistent with a relation between an increase in the rate of suicide in females and the move to fewer beds, more readmissions, and shorter stays. The lack of a trend in the male cohort implies that male patients were affected to a lesser extent by the changes in service provision. The fall in male standardised mortality ratios, with relatively stable cohort rates, may reflect the fact that younger males, whose suicide rate in the general population is increasing, are less likely than females to be in contact with health services before suicide.25

Alternatively, as numbers of beds have fallen, the admission criteria for female patients may have become more stringent. This could have led to the selective admission of severely disturbed patients, who may be more likely to commit suicide on discharge, and the decrease in the person years at risk in some diagnoses over the period supports this. A similar decrease in the same diagnostic categories, however, was observed in male patients, in whom the risk of suicide remained stable in the study cohort and fell relative to the general population. Furthermore, the effect of period was constant in all diagnostic categories, including diagnoses such as schizophrenia in which the person years at risk did not decline. Therefore, although we cannot dismiss this explanation, it is not well supported by the data.

Whatever the reason for the increase in the rates in female patients, the main finding is that their risk of suicide in the first 28 days after discharge is increasing. Some of these deaths might be avoidable if community services are targeted at this high risk period, In Scotland, although the number of beds has been reduced, no comprehensive and integrated community service is yet in place.26 If the increase is due to earlier discharge with inadequate community support, community services and planning procedures for discharge need to be developed before numbers of beds are reduced further.

We particularly acknowledge the contribution of James Boyd and Fiona O'Brien of the information and statistics division of the NHS in Scotland for their help with programming. We also thank Gary Donaldson, Scott Fleming, Joan Forrest, Philip Johnston, and Steve Kendrick (of the same division) for their help with this study. We are indebted to Alison Douglas for advising on the use of the person years program, Roger Black for his advice throughout the study, and Stephen Lawrie for his comments on the paper.