Self-harm, somatic disorders and mortality in the 3 years following a hospitalisation in psychiatry in adolescents and young adults

Background

It is estimated that almost 1 billion people worldwide suffer from a mental disorder.1 Mental disorders are also among the leading causes of disability globally,2 with a huge cost at both individual and societal levels. While the burden conferred by mental disorders spans all age groups, it is maximal in 10–29 year olds.2 The main mental disorders usually begin between childhood and young adulthood.3 Moreover, studies have shown that a younger age at onset of mental disorders is associated with worse outcomes, including increased clinical severity and poorer social functioning in the long term.3 4 Focusing on young people with a mental disorder is therefore of major importance.

Suicidal behaviour is strongly associated with mental disorders.5–10 Around 5%–10% of patients with a major mental disorder will die from suicide11–13 and 90% of people who died from suicide in high-income countries had suffered from a mental disorder.14 In adolescents and young adults, suicide is the second leading cause of death worldwide15 and intentional self-harm is very common.16 Adolescents presenting or admitted to hospital for self-harm are in turn at increased risk of premature death from suicide but also from other causes including natural causes and accidents.17 18 Mental disorders are indeed frequently comorbid with physical disorders, even at a young age,19 and are associated with an increased risk of death from so-called ‘natural causes’.20 Therefore, self-harm, somatic disorders and premature mortality from various causes all contribute to the high burden of mental disorders.

Those hospitalised for a mental disorder present a particularly high risk of suicide.6 The suicide risk is notably augmented during the first week following admission and the first week following discharge.21 In a meta-analysis of 100 studies/cohorts, Chung et al 22 estimated the risk of suicide following hospital discharge at 484/100 000 persons-year, the highest risk occurring during the first 3 months (0.3% of patients) and in those who had been hospitalised for suicidal ideas or after a suicidal act. Among mental disorders, the highest risk has been observed in those suffering from depressive or bipolar disorders, and schizophrenia.23 Interestingly, a recent meta-analysis also confirmed an increased risk of natural death following discharge from a psychiatric facility.20 Finally, the risk of re-admission for self-harm after an initial hospitalisation for mental disorder has been estimated at 6.5% within 1 year in a large cohort study in the UK.24

Our knowledge of the risk of self-harm, somatic disorders, premature death and suicide following discharge from psychiatric hospital in adolescents and young adults remains, however, limited. In the review mentioned above,22 13 studies (representing 20 cohorts) in adolescents (and none specifically in young adults) were identified for a total of less than 11 000 individuals and the largest sample reached around 3 000 patients recruited from a single hospital. Yet, sample size is critical when studying the risk of premature mortality and suicide as they are rare events in young people. Moreover, 8 of the 13 studies mentioned above were published more than 20 years ago. Increasing knowledge over the last years about the risk associated with discharge from psychiatric hospitals may have led to changes in clinical practices. However, these effects may have been counterbalanced by a reduction in psychiatric hospital beds in recent years in France and a limited investment in outpatient care for young people. New studies are, therefore, necessary to yield a more accurate picture of the situation. Finally, it is important to have a comparison group of patients with a mental disorder who have not been admitted for psychiatric hospital inpatient care. While hospitalised patients usually have more severe disorders than non-hospitalised patients, one question is whether care provided during psychiatric hospital admission and post-discharge follow-up procedures would result in a reduction of the studied risks at least to the level of non-hospitalised patients. While scientific knowledge has increased, the authors have the impression that this did not lead to sufficient organisational changes in France to mitigate the earlier pattern of findings.

Objective

The aims of the study were: (1) To measure the rates of self-harm, somatic disorders, premature mortality and suicide in the 3 years following hospitalisation for mental disorder in 2013–2014 in a very large sample of adolescents and young adults aged 12–24 years. (2) To compare the risk of these four outcomes in this sample to a large sample of non-hospitalised young individuals matched for age and sex, and to a second sample of young people with a mental disorder but not hospitalised during this period. We hypothesised that the risk of these four outcomes would be increased in people hospitalised in psychiatry as compared with both non-hospitalised and non-affected controls, and with non-hospitalised affected controls.

Methods

Findings

Hospitalisation for self-harm during follow-up

During follow-up, the rates of hospitalisation for self-harm were higher in the hospitalised patient group (9.9%) than the non-affected (0.1%; p<0.0001) and affected (6.8%; p<0.0001) control groups (table 2 and figure 1). In all three groups, hospitalisation for self-harm during follow-up occurred mainly once, and self-poisoning was the main method of self-harm. Median duration between the index hospitalisation and the first hospitalisation for self-harm during follow-up in the case group was 244 days (min=1–max=1 096).

Figure 1

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Rates (in % of the considered group) during the 3-year follow-up of hospitalisation for self-harm, hospitalisation with a somatic disorder diagnosis (top) and mortality (all-cause and suicide) (bottom) in the three groups.

Hospitalisation for mental disorder was associated with a significant unadjusted risk of subsequent hospitalisation for self-harm when compared with both the non-affected (HR=155.3, 95% CI (132.0 to 182.8)) and affected (HR=1.5, 95% CI (1.4 to 1.6)) control groups. Both risks remained significant when age, sex, a past hospitalisation with a somatic disorder diagnosis and a past hospitalisation for a self-harm were added to the model (table 3). Younger age (12–15 vs 16–18, 19–21 and 22–24 years), female sex and having been hospitalised with a somatic disorder or for self-harm during the background period were all significant risk factors for subsequent self-harm hospitalisation.

Table 3

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Adjusted risk factors for hospitalisation for self-harm, hospitalisation with a somatic disorder diagnosis, death from any cause and from suicide during the 3-year follow-up in adolescents and young adults hospitalised for a mental disorder in 2013–2014, in comparison to the non-affected control group without a mental disorder and matched for age and sex, and to the affected control group with a mental disorder but not hospitalised

In the hospitalised patient group, the most frequent mental disorder categories at the time of the index hospitalisation among those with a subsequent self-harm hospitalisation were mood disorders, neurotic and stress-related disorders and personality disorders (online supplemental table 1).

Discussion

This large cohort study of more than 70 000 youths aged 12–24 and hospitalised in psychiatry between 2013 and 2014 showed that during the 3 years following the index hospitalisation: 9.9% were hospitalised for self-harm, 28.8% were hospitalised with a somatic disorder and 0.8% died, with suicide being the cause in a large proportion of these (42.8%). These numbers were significantly higher than in young individuals with no known mental disorder but also than in never-hospitalised patients with a mental disorder, suggesting that a hospitalisation in psychiatry is a major marker for all four outcome variables.

Regarding self-harm, it has to be noted that only self-harming behaviours that led to a hospitalisation are identified in our study. Data about hospital presentation without a hospitalisation are not available. There is therefore a likely underestimation of the phenomenon that adds to the known under-coding of these acts in the hospital abstracts.26 However, hospitalised self-harm most likely represents an imperfect proxy for more severe or more lethal acts. As noted in a recent review of literature, between-study variations in rates of post-discharge self-harms are important.27 A previous study in the UK in a large population of 16–24 year olds reported a rate of self-harm hospitalisation of 5.8% within the first 12 months.24 In the present study, half of the cases of self-harm occurred within the first 8 months, emphasising the importance of the early months post-discharge. As previously shown, three-quarters of suicidal events post-discharge tend to occur during the first year.27 Identified risk factors in the present study, namely younger age, being a female and past history of self-harm, have been found in other studies.24 Finally, the mental disorders most frequently found among those who subsequently self-harmed were mood disorders, neurotic and stress-related disorders and personality disorders, being recorded for 63.5% of those hospitalised for self-harm.

Regarding suicide, data on causes of death were only available until 31 December 2015, therefore covering a follow-up period of one to 3 years, depending on the date of inclusion of individuals. Reported numbers are therefore underestimated, an underestimation that, again, adds to the known under-reporting of suicide in general. Yet, the rates were high, with 0.2% of the hospitalised patients dying by suicide during the follow-up period, half of the suicides occurring within the first year. In a recent meta-analysis of deaths in patients following discharge from psychiatric inpatient care,20 these rates reached 0.35% overall within the first 2 years (six studies) and 0.1% in adolescents (eight studies), with the highest rates found during the first 5 years. Suicide was also the main cause of death, as in our study. Mental disorders most often reported among those dying by suicide were schizophrenia and mood disorders, which is in line with previous studies.20

It is increasingly recognised that people suffering from severe mental disorder are at increased risk of having somatic disorders and prematurely dying from natural causes.20 Our study showed that this is also the case in young patients aged under 25 years. We found that among patients hospitalised in psychiatry, 38.8% had a previous hospitalisation with a somatic disorder diagnosis in the 5–7 years prior to the index hospitalisation and 28.8% during follow-up. Moreover, 18.5% of deaths were from ‘natural causes’. Most frequent diagnoses were non-intentional injuries, followed by unclear diagnoses, then digestive, endocrine, respiratory, nervous and genitourinary system diseases. These rates in hospitalised patients were much higher than in healthy controls, and to a lower extent than in affected controls. It must also be emphasised that a past history of a somatic disorder in youths with a mental disorder was also a risk factor for self-harm and premature death, above the risk conferred by the hospitalised mental disorder. It is beyond this article to discuss the mechanisms of the association between mental and somatic disorders. In a time when physical assessment and care of patients with mental disorders is increasingly emphasised, our study suggests that they should start early in this population.

Overall, these findings from a very large national cohort of young people hospitalised in psychiatry highlight the urgent need for both more research on the factors contributing to poor outcomes, and for changes in the organisation of the follow-up of young patients after a psychiatric hospitalisation. The reasons why the post-hospital discharge period remains one of high risk are multiple, including the fact that this may be a time of particular risk for patients with more severe psychiatric disorders.28 However, as often reported in recent years, needs related to mental health in young people are unfortunately often poorly met.29 Previous studies have, for instance, highlighted a reduced risk of suicide among young people who had outpatient healthcare prior to hospitalisation, longer inpatient stays or follow-up visits within 7 days from discharge.30 Based on current findings, it seems relevant to provide more intense care during the 6–12 months following discharge from hospitalisation.

Some limitations of the present study have been described above, including underestimation of self-harm and suicides due to missing coding. Moreover, several causes of death were missing while mortality data are known to be accurate. Similarly, only somatic disorders associated with a hospitalisation were included, which could have also led to underestimation. Conversely, it could be hypothesised that individuals hospitalised in psychiatry have higher rates of somatic diseases because they have been more often clinically examined than non-hospitalised individuals. While possible, it should be noted that patients not hospitalised in psychiatry also have high rates of somatic disorders during follow-up. Moreover, many potential factors contributing to the risk of the four outcome variables were not available for investigation—such as medication intake, or care received during and after hospitalisation—limiting the interpretation of the findings. Finally, we only focused here on hospitalised patients; future studies should also assess the risk of negative outcomes in patients with mental disorders treated in primary care and in outpatient psychiatric settings.

Clinical implications

During the 3 years following a hospitalisation in psychiatry, 1 in 10 young people aged 12–24 years old will be hospitalised for a self-harming behaviour, 1 in 4 will present a somatic disorder and 1 in 100 will die, mostly from suicide but also from natural causes. This national study—the largest to date in this population—underlines the importance of a reinforced multidisciplinary and holistic follow-up of young people in the months following discharge from a psychiatric hospitalisation.