To the best of our knowledge, this is the first study on mortality and causes of death among violent offenders, victims, or both using a nationwide representative sample with a very long follow-up period as we followed 48,834 men from the age of 18-20 years to about 53 years of age.
One major finding was that the mortality rate was much higher among violent offenders (12.8%), victims (15.6%), and in the offender and victim group (22%) than in the non-violent group (4.9%). Moreover, the alcohol and drug-related causes of death were very high in all three violent groups, while the other conscripts without experience of violence had died more often from neoplasms or accidents. More than one-third of the deaths in each violent group were due to alcohol or drug-related causes, compared to 14% in the non-violent group.
A third finding was that the bivariate analysis showed that having been convicted for repeated violent offense was associated with a nearly eleven fold higher hazard of dying from an alcohol or drug-related cause, while one committed offense resulted in a fourfold higher hazard of dying compared to no offence. Controlling for other risk factors showed that the figures still remained significantly elevated. Further, the fact that about one-third of the violent offenders and victims had been treated for an alcohol-related condition in hospital and about 10% for a drug-related problem means that a large proportion of the offenders and victims suffered from serious substance misuse [4
]. Even though there is a paucity of population-based studies reporting mortality rates due to substance misuse in violent offenders, some studies have shown that alcohol misuse/dependence provides four to eleven times higher risk for violence than abstainers [5
It has been argued that offenders and victims share the same environment including risky behavior like substance use and criminality, as well as mental illness [8
]. Another reason to the similarities in terms of substance use behavior and cause of death between offenders and victims could be that we only captured information on those participants who have been treated in hospital for injuries caused by violence. These participants can be considered severe victims. We consequently lack information about victims who never come to hospital but probably seek treatment on the open ward or elsewhere for violent incidents [22
We found that violent offenders who had also been hospitalized with an alcohol or drug diagnosis had about a fourfold higher risk of dying compared to violent offenders with no substance use. This is in line with results from a large Australian prison cohort study reporting that one third of the death cases were due to alcohol or substance misuse and the standard ratio of drug related mortality after leaving prison was as high as 14.5 [33
]. In another Australian study, Darke et al. found, among 400 illicit drug users, that almost all had experienced violent assault during their lifetime and 43% had experiences of self-harm and/or attempted suicide [34
]. This implies that alcohol or drug misuse in combination with violent offending elevates the risk of mortality [6
], why early prevention of alcohol and substance use will probably decrease not only the substance misuse itself, but also the risk of violence and mortality [35
Some studies have found violence to be more common among persons with psychiatric disorders compared to the general population [36
], while results from general population studies revealed that especially psychiatric disorders in combination with alcohol or substance misuse or other risk factors are associated with violence but not psychiatric disorders per se [37
]. Persons admitted to hospital for a mental disorder had a two to three fold higher mortality than the general population in a recent follow up study from Nordic countries [38
]. We found that men with mental disorder and experience of violence either as a perpetrator or as a victim had a two to four fold elevated risk to die compared to those with experience of violence without a mental disorder leading to hospitalization.
Studies have confirmed a strong association between psychiatric disorders and later suicide [12
] and all-cause mortality [5
]. Suicide has been shown to be a leading cause of death among serious violent offenders [24
]. With regard to repeated violent offenders, analyses showed a nearly fourfold higher hazard to commit suicide, and after controlling for psychiatric inpatient care, the repeaters of violence had about twofold higher suicide risk, indicating that both behaviors share common denominators like behavioral dysregulation of aggression linked to the serotonergic system [43
]. A repeated violent offense is an important risk factor for suicide regardless of comorbid psychiatric disorder or substance misuse [42
]. Moreover, violent behavior was associated with suicide risk later in life in a recent clinical study of suicide attempters [44
Our finding suggests that authorities and the health care systems should focus also on prevention of violent behavior, which in turn could prevent future suicide. Further, victimized psychiatric patients had a seven fold higher hazard of dying compared to general population indicating that violent victimization is an important risk factor to target on in the clinical work.
We found, after adjustment for early risk factors, substance misuse and psychiatric disorder at conscription for all the three groups, that the hazards for mortality due to alcohol or drug problems were about threefold higher, while for circulatory and other causes of mortality about a two to fourfold higher risk among victims and individuals with both offences and victimizations but not among the violent offenders (only). In contrast to other studies, the hazards for accidents were very low or non-significant for all the violent groups. It has been reported that especially violent offenders suffer from high impulsivity and risky behavior and are more often involved in various vehicle accidents and other types of accidents leading to serious injuries (1,5).
The participants who had both committed at least one violent crime and been victimized had the highest proportion of death cases (22%) and often also suffered from alcohol (40%) and drug misuse (15%). It has been reported elsewhere that being a victim of violence in itself is a risk factor for offending and vice versa [20
]. This violent group probably suffers from other adolescent behavioral and psychiatric problems and more often lives in an environment where criminality and substance use are common [24
]. Among the natural causes of death, neoplasm (23%) was the most common cause among the non-violent participants, which agrees with other general population studies [5
Advantages and limitations
One advantage of this nationwide, representative population study is the low non-participation rate, of about 2-3%. The reasons were mainly severe disability or congenital disorders. Use of non-anonymous questionnaires may have resulted in lower reporting of sensitive issues than may have been elicited with anonymous questionnaires. In previous studies of conscripts, although limited to Stockholm, it was found that a large proportion of those participants who had not completed the questionnaire had higher rates of criminality in adulthood. This means that the prevalence of, e.g., drug use may have been underestimated, but it does not mean that the association between the variables is biased [47
]. Furthermore, persons with antisocial or paranoid tendencies may be especially prone to deny their use of illicit drugs in non-anonymous questionnaires. Further, we do not know whether the participants had stopped or changed their substance use behavior after conscription, however alcohol or drug-related diagnoses derived from inpatient care registers can be considered a rather more robust measure of alcohol or drug use.
Another limitation of this study is, as has been mentioned above, that we were only able to include victims who had been hospitalized for injuries and we had no information about the perpetrators who had caused the injury. Likewise, information about crimes that had not come to the attention of the police is lacking.