Discussion

In this new study of a large national cohort of veterans followed up for up to 37 years, we confirm our earlier findings,3 which were based on a smaller veteran cohort and shorter follow-up, that veterans are at no overall increased risk of suicide. There was an increased risk in ESL which was explained by differences in deprivation, and the previous finding of an increased risk in female veterans is now confined to older women. Most veteran suicides occurred many years after leaving service, longer in women than men, consistent with the findings of a recent Canadian study.19 The pattern of methods of suicide in veterans reflects that in the wider community.

Our sensitivity analysis, examining the data at notional earlier end-points, indicates that concerns about an increased risk of suicide in young serving personnel in the 1990s and early 2000s20 21 may have pulled through into a real increased risk in young veterans at the same period.2 However, this excess risk has now disappeared. The reasons for this are likely to be multi-factorial. Whilst the Government’s 2010 report by Murrison22 made a clear commitment to improving mental health services for serving personnel and veterans, it is evident that the excess risk was already reducing by then. There had also been major changes to the provision of in-service support, with the establishment of a fully-integrated Defence Mental Health Service in 2004.23 Our finding of few suicides among young veterans in recent years suggests that improved in-service mental health advice and support may have been effective in reducing risk in this vulnerable group, although less so in ESL who by definition have a shorter period in service in which to benefit from it.

Our finding of evidence of an increased risk in veterans who left service at the 17–22 year point, who would generally have been senior Army non-commissioned officers and warrant officers, merits further study. There was no positive association with deprivation in this group and indeed the reverse may have been true. Those who served beyond 22 years are likely to have been commissioned officers in all three Services, or to have been senior non-commissioned officers in the Royal Navy or Royal Air Force who can serve to age 55 years. It is plausible that discharge at around age 40 years, as is the case for those serving a 22-year engagement in the Army, both coincides with a known period of vulnerability in early middle age,24 and renders it difficult to find worthwhile new employment. By contrast, those who retire and become veterans at age 55 years are largely past the high-risk age-group and, being older and in receipt of a full occupational pension, are less likely to have an expectation of moving to new full-time employment. Thus there may be grounds to re-examine the Army policy of the 22-year engagement in order to bring it into line with the engagement policies of the Royal Navy and Royal Air Force. Nonetheless it should be noted that in-service suicide rates were also high in men in the over 45-year age group, mirroring the pattern seen in civilians.21

In a study which profiled a treatment-seeking group of UK veterans, of whom over 80% reported PTSD symptoms and over 70% had common mental disorders, among those who responded to a questionnaire 68.2% were aged over 45 years, 39.2% were not in a relationship and 68.1% were not working. Nearly 60% had left service at least 15 years earlier. The majority had been in a combat role, mostly in Northern Ireland.25 We, therefore, suggest that although the popular image of mental health issues in veterans is dominated by young Iraq and Afghanistan veterans, there is an important hidden burden in older veterans who may have served elsewhere. This is supported by our finding that the median elapsed time between leaving service and completed suicide is around 20 years. The persistence of the increased risk of suicide in the 1950–1954 birth cohort which we first reported in our study to 20123 is consistent with service in Northern Ireland as a young soldier at the start of Operation BANNER in 1969, although a more detailed study of individual cases would be needed to confirm an association.

Developing predictive models for suicide which can accurately identify those at highest risk, and thereby maximise the benefit of targeting preventive interventions, presents major challenges. Large-scale studies by the US Veterans Health Administration have shown that these models fail to identify the majority of those who go on to die as a result of suicide; the best-performing, which used a Bayesian additive regression tree based on 61 predictive variables, predicted only 10.7% of the suicides which occurred in the veterans with the highest 1% of predicted risk scores. Furthermore, the model was most effective at identifying risk of suicide in the following 6 months; longer-term risk was much less likely to be detected by the model.26 27

Our finding that the risk of suicide in veterans is highest in the fifth decade of life, and that an average of 20 years elapsed between leaving service and suicide, suggests that interventions to identify suicide risk at the time of leaving service may not be effective. It also further emphasises that it is the middle-aged veterans whose need for support is greatest. However, this may not be a veteran-specific issue; it mirrors findings among middle-aged men in the wider community,1 as illustrated by our finding of no overall difference in risk between veterans and non-veterans. What may differ is the precipitating cause and therefore the approach needed to mitigate the risk. While issues such as unemployment and relationship breakdown are common to both veterans and non-veterans, a background of memories of combat-related incidents and perhaps moral injury are likely to require specialist veteran services.28 29 With the veterans of the early phases of the Iraq and Afghanistan conflicts now approaching middle age, suicide risk in these veterans should continue to be monitored for evidence of changing trends.

The major strength of this study is that it was based on a large cohort covering the whole of Scotland with up to 37 years follow-up. The International Classification of Diseases (ICD)-coded causes of death were taken from national vital records and acute and psychiatric hospital records, which are subject to regular quality assurance checks, and are therefore likely to be both accurate and complete in respect of those events occurring within Scotland.

Limitations of the study include possible lost to follow-up of subjects due to migration away from Scotland, which could not be quantified, and the lack of any follow-up data prior to 1981. As suicide is a comparatively rare outcome, the statistical power of the study was limited, even in this large cohort, and as a result, some of our findings did not achieve statistical significance. We have not considered it appropriate to dismiss these on that basis alone, especially where trend or other data supports the validity of the finding.30 We had no information on antecedent conditions managed solely as an outpatient or in primary care, however, we have made the assumption that the relative magnitude of hospital admissions reflects the relative magnitude of total cases. We had no information on the service to which a veteran had belonged (Army, Royal Navy or Royal Air Force), rank, deployment, combat exposure, lifestyle factors or adverse childhood events, so residual confounding may have been present. Veterans with reserve service only could not be identified and were included among the non-veterans; this may have reduced any observed differences between veterans and non-veterans although the number of suicides in reservists is likely to be insufficient to have had a major impact on our findings.