Journal of Affective Disorders 175 (2015) 147–151
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Research report
Suicide following self-harm: Findings from the Multicentre Study of self-harm in England, 2000–2012 Keith Hawton a,n, Helen Bergen a, Jayne Cooper b, Pauline Turnbull b, Keith Waters c, Jennifer Ness c, Nav Kapur b a
Centre for Suicide Research, University Department of Psychiatry, Warneford Hospital, Oxford, UK Centre for Suicide Prevention, Centre for Mental Health and Risk, University of Manchester, Oxford Road, Manchester, UK c Derbyshire Healthcare NHS Foundation Trust, Royal Derby Hospital, Derby, UK b
art ic l e i nf o
a b s t r a c t
Article history: Received 24 June 2014 Received in revised form 30 December 2014 Accepted 31 December 2014 Available online 8 January 2015
Background: Self-harm is a key risk factor for suicide and it is important to have contemporary information on the extent of risk. Methods: Mortality follow-up to 2012 of 40,346 self-harm patients identified in the three centres of the Multicentre Study of Self-harm in England between 2000 and 2010. Results: Nineteen per cent of deaths during the study period (N ¼2704) were by suicide, which occurred in 1.6% of patients (2.6% of males and 0.9% of females), during which time the risk was 49 times greater than the general population risk. Overall, 0.5% of individuals died by suicide in the first year, including 0.82% of males and 0.27% of females. While the absolute risk of suicide was greater in males, the risk relative to that in the general population was higher in females. Risk of suicide increased with age. While self-poisoning had been the most frequent method of self-harm, hanging was the most common method of subsequent suicide, particularly in males. The number of suicides was probably a considerable underestimate as there were also a large number of deaths recorded as accidents, the majority of which were poisonings, these often involving psychotropic drugs. Limitations: The study was focussed entirely on hospital-presenting self-harm. Conclusions: The findings underline the importance of prevention initiatives focused on the self-harm population, especially during the initial months following an episode of self-harm. Estimates using suicide and open verdicts may underestimate the true risk of suicide following self-harm; inclusion of accidental poisonings may be warranted in future risk estimates. & 2015 Elsevier B.V. All rights reserved.
Key words: Self-harm Mortality follow-up Suicide Linkage study
1. Introduction An episode of self-harm (intentional self-poisoning or self-injury) is the most important risk factor for eventual suicide (Cavanagh et al., 2003). Approximately 50–60% of people who die by suicide will have had a history of self-harm (Foster et al., 1997) with in many cases an episode shortly before their fatal act (Gairin et al., 2003), especially in frequent hospital attenders (Da Cruz et al., 2011). There have been several studies of the risk of suicide following self-harm (Carroll et al., 2014; Owens et al., 2002). These have shown that risk of suicide is somewhat lower in the UK than in several other countries, including in Europe. There have also been indications in studies from single centres that the risk of suicide following self-harm in the UK may
n Correspondence to: Centre for Suicide Research, University Department of Psychiatry, Warneford Hospital, Oxford, OX3 7JX, UK. E-mail address: [email protected] (K. Hawton).
http://dx.doi.org/10.1016/j.jad.2014.12.062 0165-0327/& 2015 Elsevier B.V. All rights reserved.
have decreased over time (Hawton and Fagg, 1988; Hawton et al., 2003b; Cooper et al., 2005). Studies from single centres clearly have limitations in terms of whether or not the findings are representative of national patterns. We have used data from the Multicentre Study of self-harm in England (Bergen et al., 2010; Hawton et al., 2007) to investigate recent findings for risk of suicide following self-harm in individuals presenting to general hospitals because of self-harm between 2000 and 2010, followed up until 2012, including by gender and age. We have also examined the relative risk of suicide in self-harm patients compared to the general population and whether the risk changed during the study period, which included the onset of the recent major economic recession. Because of increasing recognition of high rates of death by accidental poisoning in self-harm patients and the fact that many of these are likely to have been probable suicides (Palmer et al., 2014), especially in the self-harm population (Bergen et al., 2011; Hawton et al., 2006), we have also investigated deaths by this cause. The overall aim was to present contemporary findings
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on the risk of death from suicide and potential suicide following self-harm.
2. Methods 2.1. Setting and sample The study was undertaken in three centres currently involved in the Multicentre Study of self-harm in England. Data were collected on all individuals who presented with non-fatal selfharm to general hospital emergency departments (EDs) in Oxford (one), Manchester (three) and Derby (two) during the 11-year period 1st January 2000–31st December 2010. Non-fatal self-harm was defined as intentional self-poisoning or self-injury, irrespective of degree of suicidal intent (Hawton et al., 2003a). Following self-harm the majority of patients received a psychosocial assessment by specialist psychiatric clinicians (and some by ED staff). Demographic, clinical and hospital management data on each episode were collected by clinicians using standardised forms or were entered directly into a computerised system. Patients not receiving an assessment were identified through scrutiny of ED and medical records, from which more limited data were extracted by research clerks. Data recorded on these cases included demographic information and details of the method of self-injury and substances taken in self-poisoning. Episodes of repeated self-harm which resulted in representations to the same hospital were also identified and linked to specific individuals through unique personal identifiers.
2.3. Ethical approval The monitoring systems in Oxford and Derby have approval from local Health/Psychiatric Research Ethics Committees to collect data on self-harm for local and multicentre projects. Selfharm monitoring in Manchester is part of a clinical audit system, and has been ratified by the local Research Ethics Committee. All three monitoring systems are fully compliant with the Data Protection Act of 1998. All centres have approval under Section 251 of the NHS Act 2006 to collect patient identifiable information without patient consent. The centres also have ethical approval to release patient details to the Data Linkage Service of the NHS for the retrieval of mortality information on these individuals.
2.4. Statistical analyses Incidence rates for suicide (and suicide and accidental poisoning combined) within various time periods were calculated using Kaplan Meier estimates using the Stata sts list command. All individuals who were traced for any length of time were included. Censored cases were those who emigrated overseas. Nelson–Aalen cumulative hazard estimates were used to calculate cumulative percentages of suicide (and suicide and accidental poisoning combined) over the study period. Proportional hazards assumptions were tested and upheld. The analyses were conducted using SPSS v19 and Stata v10.0.
3. Results 2.2. Mortality 3.1. The sample Mortality information was supplied by the Data Linkage Service of the NHS, which traced and flagged individuals using the Central Health Register Enquiry System for patients in the England and Wales, and equivalent sources in Scotland. Individuals were followed up from 1st January 2000 to 31st December 2012; thus the minimum follow-up period was 2 years and the maximum was 13 years. In this study suicide was defined as death where the underlying cause was intentional self-harm (ICD-10 codes X60–X84) or undetermined intent (Y10–Y34), as is now customary in suicide research in the UK using official statistics (Linsley et al., 2001). Accidents (ICD-10 codes V01–X59) were grouped into ‘accidental poisoning by and exposure to noxious substances’ (X40–X49), and ‘all other accidental causes’ (V01–X59 excluding X40–X49).
A total of 41,286 individuals presented with self-harm between 2000 and 2010, of whom 940 (2.3%) could not be traced with regard to mortality. Of the remaining 40,346 traced individuals, 23.3% (N ¼9420) were from Oxford, 49.1% (N ¼19,810) from Manchester and 27.6% (N ¼11,116) from Derby. In terms of gender, 58.4% (N ¼23,569) were female, 41.5% (N ¼16,760) were male, and 0.1% (N ¼17) gender were unknown. The majority of patients were from the younger age groups (Table 1). The ages ranged from 7 to 97 years (47 (0.1%) age unknown), with a median age in females of 26 years (IQR 20) and in males of 31 years (IQR 19). The majority of self-harm episodes involved self-poisoning (80.8%), approximately one in six (15.6%) self-injury and the remainder (3.6%) both selfpoisoning and self-injury in the same episode (Table 1).
Table 1 Gender, age group distribution, and method of self-harm (SH) used by individuals at first episode of self-harm in the study period (2000–2010) for self-harm patients for whom mortality information was available. N (%) by gender
Age group (years) 10–24 25–34 35–54 55 þ All ages Method of SH Self-poisoning Self-injury Both self-poisoning and self-injury a b
Males
Females
Both genders
5431 (32.5) 4401 (26.3) 5661 (33.8) 1239 (7.4) 16,760a
10,641 (45.2) 4964 (21.1) 6525 (27.7) 1414 (6.0) 23,569a
16,072 (39.9) 9365 (23.3) 12,186 (30.3) 2653 (6.6) 40,346b
12,643 (75.4) 3476 (20.7) 643 (3.8)
19,960 (84.7) 2817 (12.0) 790 (3.4)
32,603 (80.8) 6293 (15.6) 1433 (3.6)
Includes individuals with unknown age (N¼ 47) or aged under 10 years (n¼ 7). Unknown gender (n¼ 17).
K. Hawton et al. / Journal of Affective Disorders 175 (2015) 147–151
3.2. Deaths A total of 2704/40,346 (6.7%) individuals died during the follow-up period, 4.8% females and 9.3% males. Of those who died, suicide (intentional self-harm) was recorded as cause of death in 349 (12.9%) and undetermined cause in 164 (6.1%). Thus 513 (19.0%) of the deaths were from suicide or probable suicide (henceforth referred to as ‘suicide’). Suicide was the cause of death in 330 (21.1%) of the males who died and in 183 (16.1%) of the females who died. Of the overall patient population, 1.3% had died by suicide (2.0% of males and 0.8% of females). Deaths of a further 360 (13.3%) individuals were recorded as from accidental causes and 1831 (67.7%) from any other cause. As can be seen in Table 2, nearly two-third (64.1%, N ¼ 329) of the suicides involved self-injury and over a third (35.9%, N ¼184) self-poisoning. Self-poisoning was more common in females (50.8%, N ¼ 93) than males (27.6%, N ¼91) (χ2 ¼27.6, P o0.001). The most frequent method of suicide was hanging, which was particularly common in the males (43.3% of suicides), but also occurred in nearly a third of the females (31.7%). It is notable that of the 360 deaths in which accidental death was recorded as the cause, 223 (61.9%) were poisonings, with 50 (18.1%) involving analgesics, antidepressants or tranquillisers (Table 2). 3.3. Risk of suicide by gender, age groups and time As can be seen in Fig. 1 and Table 3, the absolute risk of suicide was greater in males than females throughout the study period (overall Hazard ratio (HR)¼ 2.60, 95% confidence interval (CI) 2.17– 3.11). The risk of suicide following self-harm increased substantially with age at the time of self-harm in both genders (Table 3). This pattern was found for all periods of follow-up (except for the first six months in females aged 55 þ years). The risk of suicide was highest during the first year of followup, especially the first six months (Table 3 and Fig. 1). Overall, 0.50% (0.43–0.57) of individuals died by suicide within the first year following an initial episode of self-harm, including 0.82% (0.69–0.97) of males and 0.27% (0.21–0.35) of females. The risk over the whole study period was 1.62% (1.47–1.78) (2.57% (1.27–2.91) males and 0.95% (0.82–1.11) females).
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Table 2 Methods involved in suicide (intentional self-harm and undetermined intent)a and accidental poisonings. ICD-10 cause of death
Number (%) of deaths by gender Males
Suicides Self-poisoning with Analgesics Antidepressants/tranquillisers CO/other gas All other substances Total self-poisoning Self-injury by Hanging/suffocation Drowning Jumping from height Lying before moving object Firearms/fire/smoke/steam Sharp/blunt object All other self-injury Total self-injury Total suicides Accidental poisoning Poisoning with Analgesics Antidepressants/tranquillisers CO/other gas All other substances Total accidental poisoning
Females
Both genders
12 17 9 53 91
(3.6) (5.2) (2.7) (16.1) (27.6)
6 33 4 50 93
(3.3) (18.0) (2.2) (27.3) (50.8)
18 50 13 103 184
(3.5) ( 9.7) (2.5) (20.1) (35.9)
143 15 15 13 11 10 32 239 330
(43.3) (4.5) (4.5) (3.9) (3.3) (3.0) (9.7) (72.4)
58 (31.7) 4 (2.2) 5 (2.7) 5 (2.7) 2 (1.1) 2 (1.1) 14 (7.7) 90 (49.2) 183
201 19 20 18 13 12 46 329 513
(39.2) (3.7) (3.9) (3.5) (2.5) (2.3) (9.0) (64.1)
8 25 2 119 87
(3.3) (10.4) (0.8) (49.4) (36.1)
7 10 1 51 50
15 35 3 170 137
(4.2) (9.7) (0.8) (47.3) (38.1)
(5.9) (8.4) (0.8) (44.9) (42.0)
a ICD-10 codes: intentional self-harm (X60–X84) or undetermined intent (Y10–Y34).
3.4. Risk of suicide relative to the general population The age-adjusted risk of suicide in the study population (for individuals aged 15 years and over) in the first year following selfharm was 49 (95% CI 43–57) times greater than the annual general population risk of suicide in England and Wales based on mid-year population estimates averaged for 2001–2010. It was greater in females (59, 46–76) than males (46, 38–54), although the difference was not statistically significant. 3.5. Temporal changes in risk of suicide There appeared to be a decrease in annual risk of suicide following self-harm during the first part of the study period, though overall there was no consistent trend (χ2 for trend ¼0.18, df ¼10, P¼ 0.67) (Fig. 2). When patients in 2010 were omitted because some of the deaths for individuals presenting in that year would not have been registered by the end of 2012, the trend was somewhat more marked but still not statistically significant (χ2 for trend¼2.909, df ¼9, P ¼0.088). While the risk of death levelled off in 2006–2009 there was no actual upturn in risk following the onset of the economic recession in 2008 (although there was an increase in overall rates of self-harm in two of the centres in 2008–2010 – to be reported elsewhere). It is worth noting,
Fig. 1. Cumulative percentages of suicides over the follow-up perioda, by gender.
however, that the suicide risk in 2009 was the second highest of any year during the study period.
3.6. Risk including accidental poisonings The risk of death was considerably increased when accidental poisonings were included with suicides and open verdicts. Thus the risks of likely suicide following self-harm where accidental poisonings were included were 0.6% (0.53–0.68) in the first year (1.01% (0.87–1.17) in males and 0.31% (0.25–0.39) in females), which is 57 (95% CI 51–65) times the risk in the general population (53 (46–62) times in males and 68 (54–86) times in females), and 2.44% over the whole study period (3.87% (3.49–4.29) in males and
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Table 3 Risk of suicidea after six months, 1 year, 2 years, and 13 years of follow-up from first episode of self-harm, by gender and age group. N
Males 10–24 5431 25–34 4401 35–54 5661 55 þ 1239 Females 10–24 10,641 25–34 4964 35–54 6525 55 þ 1141 b Both genders 10–24 16,080 25–34 9367 35–54 12,191 55 þ 2654 c All ages Female 23,569 Male 16,760 All 40,346 a b c
6 months
1 year
2 years
13 years
n
% (95% CI)
n
% (95% CI)
n
% (95% CI)
n
% (95% CI)
13 23 44 22
0.24 0.52 0.78 1.81
(0.14–0.41) (0.35–0.79) (0.58–1.04) (1.20–2.74)
15 35 62 25
0.28 0.80 1.10 2.07
(0.17–0.46) (0.57–1.11) (0.86–1.41) (1.40–3.05)
21 52 83 32
0.39 1.19 1.48 2.71
(0.25–0.59) (0.90–1.55) (1.19–1.83) (1.92–3.81)
59 89 138 44
1.48 2.67 3.09 3.80
(1.11–1.98) (2.08–3.41) (2.56–3.73) (2.84–45.08)
1 1.84 (1.32–2.56) 2.31 (1.70–3.13) 3.98 (2.69–5.88)
7 9 18 13
0.07 0.18 0.28 0.09
(0.03–0.14) (0.09–0.35) (0.17–0.44) (0.53–1.61)
10 10 26 18
0.09 0.20 0.40 1.31
(0.05–0.17) (0.11–0.37) (0.27–0.59) (0.83–2.08)
13 16 37 22
0.12 0.32 0.57 1.63
(0.07–0.21) (0.20–0.53) (0.41–0.78) (1.07–2.46)
35 37 82 29
0.46 0.91 1.47 2.16
(0.32–0.67) (0.65–1.26) (1.18–1.835 (1.50–3.09)
1 2.23 (1.41–3.54) 3.85 (2.59–5.71) 7.33 (4.48–11.99)
20 32 62 35
0.12 0.34 0.51 1.35
(0.08–0.19) (0.24–0.48) (0.40–0.65) (0.97–1.87)
25 45 88 43
0.16 0.48 0.72 1.67
(0.11–0.23) (0.36–0.64) (0.59–0.89) (1.24–2.24)
34 68 120 54
0.21 0.73 0.99 2.13
(0.15–0.30) (0.57–0.92) (0.83–1.18) (1.63–2.77)
94 126 220 73
0.80 1.73 2.20 2.92
(0.64–1.01) (1.42–2.11) (1.91–2.54) (2.32–3.66)
1 2.27 (1.74–2.97) 3.14 (2.47–4.00) 5.61 (4.13–7.62)
47 102 149
0.20 (0.15–0.27) 0.61 (0.50–0.74) 0.37 (0.31–0.43)
64 137 201
0.27 (0.21–0.35) 0.82 (0.69–0.97) 0.50 (0.43–0.57)
88 188 276
0.37 (0.30–0.46) 1.13 (0.98–1.13) 0.69 (0.61–0.77)
183 330 513
0.95 (0.82–1.11) 2.57 (2.27–2.91) 1.62 (1.47–1.78)
1 2.60 (2.17–3.11)
Percentages calculated using Kaplan Meier estimates. Cases omitted with age under 10 (n¼ 7) or age unknown (n¼ 47). Cases omitted with gender unknown (n ¼17).
1.44% (1.26–1.65) in females). The pattern of risk over time was very similar to that for suicides and open verdicts alone (Fig. 1).
4. Discussion We have used data collected on self-harm patients presenting to general hospitals in the three centres (Oxford, Manchester and Derby) involved in the Multicentre Study of self-harm in England between 2000 and 2010 to estimate risk of suicide following selfharm. Estimation of suicide risk based on combined suicide and undetermined verdicts, as is customary in research in the UK (Department of Health, 2014; Linsley et al., 2001), indicated that of all deaths (N ¼ 2704) that occurred in this study up to the end of 2012 nearly one in five (19.0%) was by suicide. Of all patients, 1.6% died by suicide (2.6% of males and 0.9% of females). The risk of suicide in the first year following self-harm was 49 times greater than the general population risk of suicide in England and Wales. While the absolute risk of suicide was higher in males than females, the risk relative to the general population risk was somewhat higher in females than males, although the difference was not statistically significant. Risk of suicide increased with age at the time of self-harm. We have elsewhere reported findings concerning suicide following self-harm in older people in an earlier cohort from this study (Murphy et al., 2012). The risk of suicide was particularly high in the first year following self-harm, especially the first six months. Overall, 0.5% of individuals died by suicide in the first year, including 0.82% of males and 0.27% of females. These are somewhat lower figures than reported in some previous studies from England. Thus in studies from Oxford, Hawton and Fagg (1988) found that of patients presenting to hospital with selfharm in the late 1970s and early 1980s 1% died by suicide in the first year, and in a later study Hawton et al. (2003b) reported a figure of 0.7%. In a study from Manchester for patients who presented to hospital in the early 2000s, the equivalent figure was 0.5%. While the risk of suicide following self-harm in England may have decreased somewhat, nevertheless the risk remains high – although it appears to be lower than in other European countries (Carroll et al., 2014).
Fig. 2. Rate of suicide within one year of self-harm (SH), by years 2000–2010.
One factor that may have contributed to the reduction in risk may have been the increase in deaths recorded as accidental resulting from the greater use of narrative verdicts by coroners in England (Carroll et al., 2014; Hill and Cook, 2011). The international convention is that when deaths receiving such verdicts are given an ICD code this should be an accidental cause if no indication of suicidal intent is provided in the narrative. The number of narrative verdicts has been increasing steadily since 2000 (Hill and Cook, 2011). This could explain the reduction in risk seen between 2000 and 2005 in our study and the somewhat lower risk compared with earlier studies. We have attempted to adjust for this to some degree by conducting a secondary analysis which included deaths by accidental poisoning. This is justified by the fact that risk of suicide in which poisoning is the method used is particularly likely in selfharm patients as approximately three-quarters of those presenting to a general hospital will have used this method for non-fatal selfharm (Bergen et al., 2010; Hawton et al., 2007). Also, as we have noted, a substantial proportion of these poisonings involved psychotropic drugs, making it more likely that many were intentional overdoses. When these accidental deaths were included the risk of possible suicide in the first year following self-harm increased to 0.6% (1.01% in males and 0.31% in females), with the risk relative to the general population risk rising to 57 times (53 times in males and 68
K. Hawton et al. / Journal of Affective Disorders 175 (2015) 147–151
times in females), which are very similar levels to the risk found in self-harm patients presenting to hospital in Oxford between 1978 and 1997 who were followed up until 2000 (Hawton et al., 2003b). A likely explanation for the lower risk of suicide following selfharm in England than in some other European countries is that patients in England tend on average to be younger (Schmidtke et al., 1996), with risk of suicide, as we have shown, increasing with age (Carroll et al., 2014). While self-poisoning was the most frequent method of self-harm, hanging was the most common method used for suicide, particularly in males. We have elsewhere presented detailed results on method switching between non-fatal and fatal self-harm (Bergen et al., 2012). The key message is that people often switch methods of self-harm and that while clinicians should pay attention to potential access to methods used in a recent episode of self-harm, prevention of suicide in self-harm patients needs also to focus on broader aspects of prevention, including provision of potentially effective treatments (National Collaborating Centre for Mental Health, 2011; Fleischmann et al., 2008) and other initiatives. Thus in our earlier study (Bergen et al., 2012) we found that while one-third of self-harm patients who subsequently died by suicide used the same method for their last selfharm and for suicide, six out of ten used a different method. 5. Limitations This study is restricted to self-harm patients presenting to general hospitals. This risk of suicide following self-harm that occurs in the community and does not result in general hospital presentation is unknown. A small proportion of patients (2.3%) could not be traced with regard to mortality. Given the small number in this category it is unlikely, however, that their exclusion would have had any major effect on the findings. We do not know what proportion of those deaths recorded as accidents would have been possible suicides. However, given the proportion of deaths recorded as accidents and the points made above regarding the increase in narrative verdicts, it is likely that a substantial proportion of deaths in this category may have been suicidal in nature. Clarification of this would require detailed investigation of individual cases. We have compared suicide risk in the study cohort with risk of suicide in the general population of England. Comparison with local suicide rates might have provided a different relative level of risk (Cooper et al., 2005), but since many of the study population would have moved away from the study area before death it can be argued that use of national rates for comparison is reasonable. 6. Conclusions The findings emphasise the importance of focusing on selfharm patients in suicide prevention initiatives, especially given that over half of patients dying by suicide will have self-harmed at some time (Foster et al., 1997). They also highlight the importance of interventions focused on the initial period after a self-harm episode. Finally, in calculating estimates of suicide risk in selfharm patients', researchers need to be aware of current death classification issues that may influence the accuracy of findings. Role of funding source We acknowledge financial support from the Department of Health including the Policy Research Programme. KH is a National Institute for Health Research Senior Investigator. The Department of Health had no role in study design, the collection, analysis and interpretation of data, the writing of the manuscript, and the decision to submit the paper for publication. The views and opinions expressed do not necessarily reflect those of the Department of Health or the National Institute for Health Research.
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Conflict of interest All authors declare that they have no conflicts of interest.
Acknowledgements We thank the research staff in each centre, as well as members of the general hospital psychiatric and other clinical services, and hospital administration staff for assistance with data collection.
References Bergen, H., Hawton, K., Kapur, N., Cooper, J., Steeg, S., Ness, J., Waters, K., 2011. Shared characteristics of suicides and other unnatural deaths following nonfatal self-harm? A multicentre study of risk factors. Psychol. Med. 42, 727–741. Bergen, H., Hawton, K., Waters, K., Cooper, J., Kapur, N., 2010. Epidemiology and trends in non-fatal self-harm in three centres in England, 2000 to 2007. Br. J. Psychiatry 197, 493–498. Bergen, H., Hawton, K., Waters, K., Ness, J., Cooper, J., Steeg, S., Kapur, N., 2012. How do methods of non-fatal self-harm relate to eventual suicide? J. Affect. Disord. 136, 526–533. Carroll, R., Metcalfe, C., Gunnell, D., 2014. Hospital presenting self-harm and risk of fatal and non-fatal repetition: Systematic review and meta-analysis. PLoS ONE 9, e89944, http://dx.doi.org/10.1371/journal.pone.0089944. Cavanagh, J.T.O., Carson, A.J., Sharpe, M., Lawrie, S.M., 2003. Psychological autopsy studies of suicide: a systematic review. Psychol. Med. 33, 395–405. Cooper, J., Kapur, N., Webb, R., Lawlor, M., Guthrie, E., Mackway-Jones, K., Appleby, L., 2005. Suicide after deliberate self-harm: a 4-year cohort study. Am. J. Psychiatry 162, 297–303. Da Cruz, D., Pearson, A., Saini, P., Miles, C., While, D., Swinson, N., Williams, A., Shaw, J., Appleby, L., Kapur, N., 2011. Emergency department contact prior to suicide in mental health patients. Emerg. Med. J. 28, 467–471. Department of Health, 2014. Preventing suicide in England: one year on (First Annual Report on the Cross-Government Outcomes Strategy to Save Lives). HM Government, London. Fleischmann, A., Bertolote, J.M., Wasserman, D., de Leo, D., Bolhari, J, Botega, N.J., de Silva, D., Phillips, M., Vijayakumar, L., Värnik, A., Schlebusch, L., Thanh, H.T.T., 2008. Effectiveness of brief intervention and contact for suicide attempters: a randomized controlled trial in five countries. Bull. World Health Organ. 86, 703–709. Foster, T., Gillespie, K., McClelland, R., 1997. Mental disorders and suicide in Northern Ireland. Br. J. Psychiatry 170, 447–452. Gairin, I., House, A., Owens, D., 2003. Attendance at the accident and emergency department in the year before suicide: retrospective study. Br. J. Psychiatry 183, 28–33. Hawton, K., Bergen, H., Casey, D., Simkin, S., Palmer, B., Cooper, J., Kapur, N., Horrocks, J., House, A., Lilley, R., Noble, R., Owens, D., 2007. Self-harm in England: a tale of three cities. Multicentre study of self-harm. Soc. Psychiatry Psychiatr. Epidemiol. 42, 513–521. Hawton, K., Fagg, J., 1988. Suicide, and other causes of death, following attempted suicide. Br. J. Psychiatry 152, 359–366. Hawton, K., Harriss, L., Hall, S., Simkin, S., Bale, E., Bond, A., 2003a. Deliberate selfharm in Oxford, 1990–2000: a time of change in patient characteristics. Psychol. Med. 33, 987–996. Hawton, K., Harriss, L., Zahl, D., 2006. Deaths from all causes in a long-term followup study of 11,583 deliberate self harm patients. Psychol. Med. 36, 397–405. Hawton, K., Zahl, D., Weatherall, R., 2003b. Suicide following deliberate self-harm: long-term follow-up of patients who presented to a general hospital. Br. J. Psychiatry 182, 537–542. Hill, C., Cook, L., 2011. Narrative verdicts and their impact on mortality statistics in England and Wales. Health Stat. Q. 49, 81–100. Linsley, K.R., Schapira, K., Kelly, T.P., 2001. Open verdict v. suicide – importance to research. Br. J. Psychiatry 178, 465–468. Murphy, E., Kapur, N., Webb, R., Purandare, N., Hawton, K., Bergen, H., Waters, K., Cooper, J., 2012. Multicentre cohort study of older adults who have harmed themselves: risk factors for repetition and suicide Br. J. Psychiatry 200, 399–404. National Collaborating Centre for Mental Health, 2011. Self-harm (longer term management) (Clinical Guideline 133). National Institute for Clinical Excellence, London. Owens, D., Horrocks, J., House, A., 2002. Fatal and non-fatal repetition of self-harm. Systematic review. Br. J. Psychiatry 181, 193–199. Palmer, B.S., Bennewith, O., Simkin, S., Cooper, J., Hawton, K., Kapur, N., Gunnell, D., 2014. Factors influencing coroners' verdicts: an analysis of verdicts given by 12 coroners to researcher-defined suicides in England in 2005, http://dx.doi.org/ 10.1093/pubmed/fdu024. Schmidtke, A., Bille Brahe, U., De Leo, D., Kerkhof, A., Bjerke, T., Crepet, P., Haring, C., Hawton, K., Lönnqvist, J., Michel, K., Pommereau, X., Querejeta, I., Phillipe, I., Salander Renberg, E., Temesvary, B., Wasserman, D., Fricke, S., Weinacker, B., Sampaio Faria, J.G., 1996. Attempted suicide in Europe: rates, trends and sociodemographic characteristics of suicide attempters during the period 1989–1992. Results of the WHO/EURO Multicentre Study on Parasuicide. Acta Psychiatr. Scand. 93, 327–338.
Contents lists available at ScienceDirect
Journal of Affective Disorders journal homepage: www.elsevier.com/locate/jad
Research report
Suicide following self-harm: Findings from the Multicentre Study of self-harm in England, 2000–2012 Keith Hawton a,n, Helen Bergen a, Jayne Cooper b, Pauline Turnbull b, Keith Waters c, Jennifer Ness c, Nav Kapur b a
Centre for Suicide Research, University Department of Psychiatry, Warneford Hospital, Oxford, UK Centre for Suicide Prevention, Centre for Mental Health and Risk, University of Manchester, Oxford Road, Manchester, UK c Derbyshire Healthcare NHS Foundation Trust, Royal Derby Hospital, Derby, UK b
art ic l e i nf o
a b s t r a c t
Article history: Received 24 June 2014 Received in revised form 30 December 2014 Accepted 31 December 2014 Available online 8 January 2015
Background: Self-harm is a key risk factor for suicide and it is important to have contemporary information on the extent of risk. Methods: Mortality follow-up to 2012 of 40,346 self-harm patients identified in the three centres of the Multicentre Study of Self-harm in England between 2000 and 2010. Results: Nineteen per cent of deaths during the study period (N ¼2704) were by suicide, which occurred in 1.6% of patients (2.6% of males and 0.9% of females), during which time the risk was 49 times greater than the general population risk. Overall, 0.5% of individuals died by suicide in the first year, including 0.82% of males and 0.27% of females. While the absolute risk of suicide was greater in males, the risk relative to that in the general population was higher in females. Risk of suicide increased with age. While self-poisoning had been the most frequent method of self-harm, hanging was the most common method of subsequent suicide, particularly in males. The number of suicides was probably a considerable underestimate as there were also a large number of deaths recorded as accidents, the majority of which were poisonings, these often involving psychotropic drugs. Limitations: The study was focussed entirely on hospital-presenting self-harm. Conclusions: The findings underline the importance of prevention initiatives focused on the self-harm population, especially during the initial months following an episode of self-harm. Estimates using suicide and open verdicts may underestimate the true risk of suicide following self-harm; inclusion of accidental poisonings may be warranted in future risk estimates. & 2015 Elsevier B.V. All rights reserved.
Key words: Self-harm Mortality follow-up Suicide Linkage study
1. Introduction An episode of self-harm (intentional self-poisoning or self-injury) is the most important risk factor for eventual suicide (Cavanagh et al., 2003). Approximately 50–60% of people who die by suicide will have had a history of self-harm (Foster et al., 1997) with in many cases an episode shortly before their fatal act (Gairin et al., 2003), especially in frequent hospital attenders (Da Cruz et al., 2011). There have been several studies of the risk of suicide following self-harm (Carroll et al., 2014; Owens et al., 2002). These have shown that risk of suicide is somewhat lower in the UK than in several other countries, including in Europe. There have also been indications in studies from single centres that the risk of suicide following self-harm in the UK may
n Correspondence to: Centre for Suicide Research, University Department of Psychiatry, Warneford Hospital, Oxford, OX3 7JX, UK. E-mail address: [email protected] (K. Hawton).
http://dx.doi.org/10.1016/j.jad.2014.12.062 0165-0327/& 2015 Elsevier B.V. All rights reserved.
have decreased over time (Hawton and Fagg, 1988; Hawton et al., 2003b; Cooper et al., 2005). Studies from single centres clearly have limitations in terms of whether or not the findings are representative of national patterns. We have used data from the Multicentre Study of self-harm in England (Bergen et al., 2010; Hawton et al., 2007) to investigate recent findings for risk of suicide following self-harm in individuals presenting to general hospitals because of self-harm between 2000 and 2010, followed up until 2012, including by gender and age. We have also examined the relative risk of suicide in self-harm patients compared to the general population and whether the risk changed during the study period, which included the onset of the recent major economic recession. Because of increasing recognition of high rates of death by accidental poisoning in self-harm patients and the fact that many of these are likely to have been probable suicides (Palmer et al., 2014), especially in the self-harm population (Bergen et al., 2011; Hawton et al., 2006), we have also investigated deaths by this cause. The overall aim was to present contemporary findings
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on the risk of death from suicide and potential suicide following self-harm.
2. Methods 2.1. Setting and sample The study was undertaken in three centres currently involved in the Multicentre Study of self-harm in England. Data were collected on all individuals who presented with non-fatal selfharm to general hospital emergency departments (EDs) in Oxford (one), Manchester (three) and Derby (two) during the 11-year period 1st January 2000–31st December 2010. Non-fatal self-harm was defined as intentional self-poisoning or self-injury, irrespective of degree of suicidal intent (Hawton et al., 2003a). Following self-harm the majority of patients received a psychosocial assessment by specialist psychiatric clinicians (and some by ED staff). Demographic, clinical and hospital management data on each episode were collected by clinicians using standardised forms or were entered directly into a computerised system. Patients not receiving an assessment were identified through scrutiny of ED and medical records, from which more limited data were extracted by research clerks. Data recorded on these cases included demographic information and details of the method of self-injury and substances taken in self-poisoning. Episodes of repeated self-harm which resulted in representations to the same hospital were also identified and linked to specific individuals through unique personal identifiers.
2.3. Ethical approval The monitoring systems in Oxford and Derby have approval from local Health/Psychiatric Research Ethics Committees to collect data on self-harm for local and multicentre projects. Selfharm monitoring in Manchester is part of a clinical audit system, and has been ratified by the local Research Ethics Committee. All three monitoring systems are fully compliant with the Data Protection Act of 1998. All centres have approval under Section 251 of the NHS Act 2006 to collect patient identifiable information without patient consent. The centres also have ethical approval to release patient details to the Data Linkage Service of the NHS for the retrieval of mortality information on these individuals.
2.4. Statistical analyses Incidence rates for suicide (and suicide and accidental poisoning combined) within various time periods were calculated using Kaplan Meier estimates using the Stata sts list command. All individuals who were traced for any length of time were included. Censored cases were those who emigrated overseas. Nelson–Aalen cumulative hazard estimates were used to calculate cumulative percentages of suicide (and suicide and accidental poisoning combined) over the study period. Proportional hazards assumptions were tested and upheld. The analyses were conducted using SPSS v19 and Stata v10.0.
3. Results 2.2. Mortality 3.1. The sample Mortality information was supplied by the Data Linkage Service of the NHS, which traced and flagged individuals using the Central Health Register Enquiry System for patients in the England and Wales, and equivalent sources in Scotland. Individuals were followed up from 1st January 2000 to 31st December 2012; thus the minimum follow-up period was 2 years and the maximum was 13 years. In this study suicide was defined as death where the underlying cause was intentional self-harm (ICD-10 codes X60–X84) or undetermined intent (Y10–Y34), as is now customary in suicide research in the UK using official statistics (Linsley et al., 2001). Accidents (ICD-10 codes V01–X59) were grouped into ‘accidental poisoning by and exposure to noxious substances’ (X40–X49), and ‘all other accidental causes’ (V01–X59 excluding X40–X49).
A total of 41,286 individuals presented with self-harm between 2000 and 2010, of whom 940 (2.3%) could not be traced with regard to mortality. Of the remaining 40,346 traced individuals, 23.3% (N ¼9420) were from Oxford, 49.1% (N ¼19,810) from Manchester and 27.6% (N ¼11,116) from Derby. In terms of gender, 58.4% (N ¼23,569) were female, 41.5% (N ¼16,760) were male, and 0.1% (N ¼17) gender were unknown. The majority of patients were from the younger age groups (Table 1). The ages ranged from 7 to 97 years (47 (0.1%) age unknown), with a median age in females of 26 years (IQR 20) and in males of 31 years (IQR 19). The majority of self-harm episodes involved self-poisoning (80.8%), approximately one in six (15.6%) self-injury and the remainder (3.6%) both selfpoisoning and self-injury in the same episode (Table 1).
Table 1 Gender, age group distribution, and method of self-harm (SH) used by individuals at first episode of self-harm in the study period (2000–2010) for self-harm patients for whom mortality information was available. N (%) by gender
Age group (years) 10–24 25–34 35–54 55 þ All ages Method of SH Self-poisoning Self-injury Both self-poisoning and self-injury a b
Males
Females
Both genders
5431 (32.5) 4401 (26.3) 5661 (33.8) 1239 (7.4) 16,760a
10,641 (45.2) 4964 (21.1) 6525 (27.7) 1414 (6.0) 23,569a
16,072 (39.9) 9365 (23.3) 12,186 (30.3) 2653 (6.6) 40,346b
12,643 (75.4) 3476 (20.7) 643 (3.8)
19,960 (84.7) 2817 (12.0) 790 (3.4)
32,603 (80.8) 6293 (15.6) 1433 (3.6)
Includes individuals with unknown age (N¼ 47) or aged under 10 years (n¼ 7). Unknown gender (n¼ 17).
K. Hawton et al. / Journal of Affective Disorders 175 (2015) 147–151
3.2. Deaths A total of 2704/40,346 (6.7%) individuals died during the follow-up period, 4.8% females and 9.3% males. Of those who died, suicide (intentional self-harm) was recorded as cause of death in 349 (12.9%) and undetermined cause in 164 (6.1%). Thus 513 (19.0%) of the deaths were from suicide or probable suicide (henceforth referred to as ‘suicide’). Suicide was the cause of death in 330 (21.1%) of the males who died and in 183 (16.1%) of the females who died. Of the overall patient population, 1.3% had died by suicide (2.0% of males and 0.8% of females). Deaths of a further 360 (13.3%) individuals were recorded as from accidental causes and 1831 (67.7%) from any other cause. As can be seen in Table 2, nearly two-third (64.1%, N ¼ 329) of the suicides involved self-injury and over a third (35.9%, N ¼184) self-poisoning. Self-poisoning was more common in females (50.8%, N ¼ 93) than males (27.6%, N ¼91) (χ2 ¼27.6, P o0.001). The most frequent method of suicide was hanging, which was particularly common in the males (43.3% of suicides), but also occurred in nearly a third of the females (31.7%). It is notable that of the 360 deaths in which accidental death was recorded as the cause, 223 (61.9%) were poisonings, with 50 (18.1%) involving analgesics, antidepressants or tranquillisers (Table 2). 3.3. Risk of suicide by gender, age groups and time As can be seen in Fig. 1 and Table 3, the absolute risk of suicide was greater in males than females throughout the study period (overall Hazard ratio (HR)¼ 2.60, 95% confidence interval (CI) 2.17– 3.11). The risk of suicide following self-harm increased substantially with age at the time of self-harm in both genders (Table 3). This pattern was found for all periods of follow-up (except for the first six months in females aged 55 þ years). The risk of suicide was highest during the first year of followup, especially the first six months (Table 3 and Fig. 1). Overall, 0.50% (0.43–0.57) of individuals died by suicide within the first year following an initial episode of self-harm, including 0.82% (0.69–0.97) of males and 0.27% (0.21–0.35) of females. The risk over the whole study period was 1.62% (1.47–1.78) (2.57% (1.27–2.91) males and 0.95% (0.82–1.11) females).
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Table 2 Methods involved in suicide (intentional self-harm and undetermined intent)a and accidental poisonings. ICD-10 cause of death
Number (%) of deaths by gender Males
Suicides Self-poisoning with Analgesics Antidepressants/tranquillisers CO/other gas All other substances Total self-poisoning Self-injury by Hanging/suffocation Drowning Jumping from height Lying before moving object Firearms/fire/smoke/steam Sharp/blunt object All other self-injury Total self-injury Total suicides Accidental poisoning Poisoning with Analgesics Antidepressants/tranquillisers CO/other gas All other substances Total accidental poisoning
Females
Both genders
12 17 9 53 91
(3.6) (5.2) (2.7) (16.1) (27.6)
6 33 4 50 93
(3.3) (18.0) (2.2) (27.3) (50.8)
18 50 13 103 184
(3.5) ( 9.7) (2.5) (20.1) (35.9)
143 15 15 13 11 10 32 239 330
(43.3) (4.5) (4.5) (3.9) (3.3) (3.0) (9.7) (72.4)
58 (31.7) 4 (2.2) 5 (2.7) 5 (2.7) 2 (1.1) 2 (1.1) 14 (7.7) 90 (49.2) 183
201 19 20 18 13 12 46 329 513
(39.2) (3.7) (3.9) (3.5) (2.5) (2.3) (9.0) (64.1)
8 25 2 119 87
(3.3) (10.4) (0.8) (49.4) (36.1)
7 10 1 51 50
15 35 3 170 137
(4.2) (9.7) (0.8) (47.3) (38.1)
(5.9) (8.4) (0.8) (44.9) (42.0)
a ICD-10 codes: intentional self-harm (X60–X84) or undetermined intent (Y10–Y34).
3.4. Risk of suicide relative to the general population The age-adjusted risk of suicide in the study population (for individuals aged 15 years and over) in the first year following selfharm was 49 (95% CI 43–57) times greater than the annual general population risk of suicide in England and Wales based on mid-year population estimates averaged for 2001–2010. It was greater in females (59, 46–76) than males (46, 38–54), although the difference was not statistically significant. 3.5. Temporal changes in risk of suicide There appeared to be a decrease in annual risk of suicide following self-harm during the first part of the study period, though overall there was no consistent trend (χ2 for trend ¼0.18, df ¼10, P¼ 0.67) (Fig. 2). When patients in 2010 were omitted because some of the deaths for individuals presenting in that year would not have been registered by the end of 2012, the trend was somewhat more marked but still not statistically significant (χ2 for trend¼2.909, df ¼9, P ¼0.088). While the risk of death levelled off in 2006–2009 there was no actual upturn in risk following the onset of the economic recession in 2008 (although there was an increase in overall rates of self-harm in two of the centres in 2008–2010 – to be reported elsewhere). It is worth noting,
Fig. 1. Cumulative percentages of suicides over the follow-up perioda, by gender.
however, that the suicide risk in 2009 was the second highest of any year during the study period.
3.6. Risk including accidental poisonings The risk of death was considerably increased when accidental poisonings were included with suicides and open verdicts. Thus the risks of likely suicide following self-harm where accidental poisonings were included were 0.6% (0.53–0.68) in the first year (1.01% (0.87–1.17) in males and 0.31% (0.25–0.39) in females), which is 57 (95% CI 51–65) times the risk in the general population (53 (46–62) times in males and 68 (54–86) times in females), and 2.44% over the whole study period (3.87% (3.49–4.29) in males and
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Table 3 Risk of suicidea after six months, 1 year, 2 years, and 13 years of follow-up from first episode of self-harm, by gender and age group. N
Males 10–24 5431 25–34 4401 35–54 5661 55 þ 1239 Females 10–24 10,641 25–34 4964 35–54 6525 55 þ 1141 b Both genders 10–24 16,080 25–34 9367 35–54 12,191 55 þ 2654 c All ages Female 23,569 Male 16,760 All 40,346 a b c
6 months
1 year
2 years
13 years
n
% (95% CI)
n
% (95% CI)
n
% (95% CI)
n
% (95% CI)
13 23 44 22
0.24 0.52 0.78 1.81
(0.14–0.41) (0.35–0.79) (0.58–1.04) (1.20–2.74)
15 35 62 25
0.28 0.80 1.10 2.07
(0.17–0.46) (0.57–1.11) (0.86–1.41) (1.40–3.05)
21 52 83 32
0.39 1.19 1.48 2.71
(0.25–0.59) (0.90–1.55) (1.19–1.83) (1.92–3.81)
59 89 138 44
1.48 2.67 3.09 3.80
(1.11–1.98) (2.08–3.41) (2.56–3.73) (2.84–45.08)
1 1.84 (1.32–2.56) 2.31 (1.70–3.13) 3.98 (2.69–5.88)
7 9 18 13
0.07 0.18 0.28 0.09
(0.03–0.14) (0.09–0.35) (0.17–0.44) (0.53–1.61)
10 10 26 18
0.09 0.20 0.40 1.31
(0.05–0.17) (0.11–0.37) (0.27–0.59) (0.83–2.08)
13 16 37 22
0.12 0.32 0.57 1.63
(0.07–0.21) (0.20–0.53) (0.41–0.78) (1.07–2.46)
35 37 82 29
0.46 0.91 1.47 2.16
(0.32–0.67) (0.65–1.26) (1.18–1.835 (1.50–3.09)
1 2.23 (1.41–3.54) 3.85 (2.59–5.71) 7.33 (4.48–11.99)
20 32 62 35
0.12 0.34 0.51 1.35
(0.08–0.19) (0.24–0.48) (0.40–0.65) (0.97–1.87)
25 45 88 43
0.16 0.48 0.72 1.67
(0.11–0.23) (0.36–0.64) (0.59–0.89) (1.24–2.24)
34 68 120 54
0.21 0.73 0.99 2.13
(0.15–0.30) (0.57–0.92) (0.83–1.18) (1.63–2.77)
94 126 220 73
0.80 1.73 2.20 2.92
(0.64–1.01) (1.42–2.11) (1.91–2.54) (2.32–3.66)
1 2.27 (1.74–2.97) 3.14 (2.47–4.00) 5.61 (4.13–7.62)
47 102 149
0.20 (0.15–0.27) 0.61 (0.50–0.74) 0.37 (0.31–0.43)
64 137 201
0.27 (0.21–0.35) 0.82 (0.69–0.97) 0.50 (0.43–0.57)
88 188 276
0.37 (0.30–0.46) 1.13 (0.98–1.13) 0.69 (0.61–0.77)
183 330 513
0.95 (0.82–1.11) 2.57 (2.27–2.91) 1.62 (1.47–1.78)
1 2.60 (2.17–3.11)
Percentages calculated using Kaplan Meier estimates. Cases omitted with age under 10 (n¼ 7) or age unknown (n¼ 47). Cases omitted with gender unknown (n ¼17).
1.44% (1.26–1.65) in females). The pattern of risk over time was very similar to that for suicides and open verdicts alone (Fig. 1).
4. Discussion We have used data collected on self-harm patients presenting to general hospitals in the three centres (Oxford, Manchester and Derby) involved in the Multicentre Study of self-harm in England between 2000 and 2010 to estimate risk of suicide following selfharm. Estimation of suicide risk based on combined suicide and undetermined verdicts, as is customary in research in the UK (Department of Health, 2014; Linsley et al., 2001), indicated that of all deaths (N ¼ 2704) that occurred in this study up to the end of 2012 nearly one in five (19.0%) was by suicide. Of all patients, 1.6% died by suicide (2.6% of males and 0.9% of females). The risk of suicide in the first year following self-harm was 49 times greater than the general population risk of suicide in England and Wales. While the absolute risk of suicide was higher in males than females, the risk relative to the general population risk was somewhat higher in females than males, although the difference was not statistically significant. Risk of suicide increased with age at the time of self-harm. We have elsewhere reported findings concerning suicide following self-harm in older people in an earlier cohort from this study (Murphy et al., 2012). The risk of suicide was particularly high in the first year following self-harm, especially the first six months. Overall, 0.5% of individuals died by suicide in the first year, including 0.82% of males and 0.27% of females. These are somewhat lower figures than reported in some previous studies from England. Thus in studies from Oxford, Hawton and Fagg (1988) found that of patients presenting to hospital with selfharm in the late 1970s and early 1980s 1% died by suicide in the first year, and in a later study Hawton et al. (2003b) reported a figure of 0.7%. In a study from Manchester for patients who presented to hospital in the early 2000s, the equivalent figure was 0.5%. While the risk of suicide following self-harm in England may have decreased somewhat, nevertheless the risk remains high – although it appears to be lower than in other European countries (Carroll et al., 2014).
Fig. 2. Rate of suicide within one year of self-harm (SH), by years 2000–2010.
One factor that may have contributed to the reduction in risk may have been the increase in deaths recorded as accidental resulting from the greater use of narrative verdicts by coroners in England (Carroll et al., 2014; Hill and Cook, 2011). The international convention is that when deaths receiving such verdicts are given an ICD code this should be an accidental cause if no indication of suicidal intent is provided in the narrative. The number of narrative verdicts has been increasing steadily since 2000 (Hill and Cook, 2011). This could explain the reduction in risk seen between 2000 and 2005 in our study and the somewhat lower risk compared with earlier studies. We have attempted to adjust for this to some degree by conducting a secondary analysis which included deaths by accidental poisoning. This is justified by the fact that risk of suicide in which poisoning is the method used is particularly likely in selfharm patients as approximately three-quarters of those presenting to a general hospital will have used this method for non-fatal selfharm (Bergen et al., 2010; Hawton et al., 2007). Also, as we have noted, a substantial proportion of these poisonings involved psychotropic drugs, making it more likely that many were intentional overdoses. When these accidental deaths were included the risk of possible suicide in the first year following self-harm increased to 0.6% (1.01% in males and 0.31% in females), with the risk relative to the general population risk rising to 57 times (53 times in males and 68
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times in females), which are very similar levels to the risk found in self-harm patients presenting to hospital in Oxford between 1978 and 1997 who were followed up until 2000 (Hawton et al., 2003b). A likely explanation for the lower risk of suicide following selfharm in England than in some other European countries is that patients in England tend on average to be younger (Schmidtke et al., 1996), with risk of suicide, as we have shown, increasing with age (Carroll et al., 2014). While self-poisoning was the most frequent method of self-harm, hanging was the most common method used for suicide, particularly in males. We have elsewhere presented detailed results on method switching between non-fatal and fatal self-harm (Bergen et al., 2012). The key message is that people often switch methods of self-harm and that while clinicians should pay attention to potential access to methods used in a recent episode of self-harm, prevention of suicide in self-harm patients needs also to focus on broader aspects of prevention, including provision of potentially effective treatments (National Collaborating Centre for Mental Health, 2011; Fleischmann et al., 2008) and other initiatives. Thus in our earlier study (Bergen et al., 2012) we found that while one-third of self-harm patients who subsequently died by suicide used the same method for their last selfharm and for suicide, six out of ten used a different method. 5. Limitations This study is restricted to self-harm patients presenting to general hospitals. This risk of suicide following self-harm that occurs in the community and does not result in general hospital presentation is unknown. A small proportion of patients (2.3%) could not be traced with regard to mortality. Given the small number in this category it is unlikely, however, that their exclusion would have had any major effect on the findings. We do not know what proportion of those deaths recorded as accidents would have been possible suicides. However, given the proportion of deaths recorded as accidents and the points made above regarding the increase in narrative verdicts, it is likely that a substantial proportion of deaths in this category may have been suicidal in nature. Clarification of this would require detailed investigation of individual cases. We have compared suicide risk in the study cohort with risk of suicide in the general population of England. Comparison with local suicide rates might have provided a different relative level of risk (Cooper et al., 2005), but since many of the study population would have moved away from the study area before death it can be argued that use of national rates for comparison is reasonable. 6. Conclusions The findings emphasise the importance of focusing on selfharm patients in suicide prevention initiatives, especially given that over half of patients dying by suicide will have self-harmed at some time (Foster et al., 1997). They also highlight the importance of interventions focused on the initial period after a self-harm episode. Finally, in calculating estimates of suicide risk in selfharm patients', researchers need to be aware of current death classification issues that may influence the accuracy of findings. Role of funding source We acknowledge financial support from the Department of Health including the Policy Research Programme. KH is a National Institute for Health Research Senior Investigator. The Department of Health had no role in study design, the collection, analysis and interpretation of data, the writing of the manuscript, and the decision to submit the paper for publication. The views and opinions expressed do not necessarily reflect those of the Department of Health or the National Institute for Health Research.
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Conflict of interest All authors declare that they have no conflicts of interest.
Acknowledgements We thank the research staff in each centre, as well as members of the general hospital psychiatric and other clinical services, and hospital administration staff for assistance with data collection.
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