Correlates of Reduced Violent Behavior Among Patients Receiving Intensive Treatment for Posttraumatic Stress Disorder

Descriptive information about the sample appears in Table 1. Data were available for 35,330 patients at the time of program entry and for 24,099 patients (68.2%) at follow-up, four months after discharge. At program entry, data on violence in the past four months were available for 33,809 patients; 44% (N=14,876) reported that they had destroyed property at some point in the past four months. This figure declined to 23% (N=7,776) at follow-up. At program entry, 58% reported threatening someone without a weapon, 30% reported being involved in a physical fight, and 17% reported threatening someone with a weapon in the past four months. These figures declined to 40%, 15%, and 8%, respectively, at follow-up.

The mean±SD total violence score on program entry was 1.49±1.34. The mean total violence score at follow-up was .91±1.42. The mean change in the violence score from baseline to follow-up (–.58) generated an effect size of –.44. In other words, mean violence at discharge was .44 SDs below the mean violence at program entry. This represents moderate effect size by Cohen’s criteria (19).

After controlling for baseline values of violence and baseline values of all other change measures, we found that many of the background measures were significantly associated with reduction in violence on bivariate analysis (Table 2). The regression coefficients were moderate in size. Thus increased age, being male, educational attainment, being white, being married, and year of program entry were associated with greater reduction in violence (as indicated by a negative coefficient) between treatment entry and follow-up than was the case for the group as a whole, and having a history of incarceration was associated with a smaller reduction in violence (as indicated by a positive coefficient).

Measures of clinical status at the time of program entry, with the exception of substance abuse diagnoses, where the regression coefficients were very small, were not significantly correlated with a change in violence at follow-up. Measures of treatment participation (length of stay, commitment to therapy as rated by program staff, and successfully completing the program) were significantly correlated with a change in violence at follow-up, but the regression coefficients were again small.

Larger, positive, regression coefficients were evident for the measures of clinical change between intake and follow-up. Improved employment (that is, a positive value for the change variable), reduced alcohol use and reduced drug use (a negative value for the change variable) were associated with a reduction in violence beyond what would have otherwise been attributed to baseline status and regression to the mean. Reductions in PTSD symptoms (reflected in negative values for the change variables) were also positively correlated with reductions in violence beyond those for the sample as a whole. This was the case for both individual subscales and total PTSD score.

When expressed as standardized estimates, regression coefficients allow effect size to be calibrated in terms of SDs. Table 2 shows that a reduction in the total PTSD score of one SD (for example, from its mean at program entry of 3.5 to 3.0) was associated with a reduction in the violence score at follow-up of .327 SDs (for example, from its mean at follow-up of .91 to .46).

The results of the stepwise regression are shown in Table 3. The largest contributor to the adjusted R² was violence at program entry, with a large negative coefficient showing that higher baseline levels of violence were associated with greater reductions in violence at four-month follow-up. Measures of alcohol use, drug use, and unemployment at program entry made small contributions to the adjusted R², with a somewhat larger contribution coming from overall PTSD symptoms at program entry. The only change variable contributing significantly to the change in adjusted R² was a change in alcohol use between program entry and follow-up.

Stepwise logistic regression models examining separately the four dichotomous violence items at follow-up confirmed that a reduction in alcohol use remained significantly associated with a reduction in each violent behavior.

This study showed that scores on a standard measure of violent behavior declined significantly in a sample of combat veterans treated in specialized intensive PTSD treatment programs between entry into a program and four months postdischarge with a moderate effect size (r=–.44). The correlations between changes in violent behavior and clinical variables, including changes in PTSD symptoms and substance use, have not been demonstrated previously in a sample of veterans receiving intensive treatment. Several aspects of the results warrant further comment.

First, the reduction in violence in this study was somewhat smaller in magnitude for patients who were younger, female, less educated, nonwhite, and not married; who had a history of incarceration; and who been abusing alcohol or drugs when they entered treatment. Female gender has elsewhere been found to be a protective factor against violence, although in mental health samples this effect is often lost as it was here (21,22). The remaining variables that were associated with smaller reductions in violence have consistently been shown to be associated with violent behavior in a range of samples and settings (23,24). We have shown that these variables were also associated with less decline in violence following treatment.

Second, the move away from long-term inpatient treatment in the VHA, as reflected in the year of program entry, was associated with a small but significantly greater reduction in violent behavior. This is consistent with evidence from other studies that the move away from long-term inpatient treatment for PTSD has led to greater clinical improvement, both at discharge and follow-up (15). On the other hand, we found little evidence that treatment participation—as measured by length of stay, commitment to treatment, or successful completion of the program—was associated with substantial reductions in violent behavior. The effect sizes were small and not significant in multivariate analysis. Treatment may have had benefits that were not detected by these therapy-related measures.

Third, on bivariate analysis the reduction in violence was greatest for patients with reductions in substance use and PTSD symptoms. Reduced alcohol use and PTSD symptoms at program entry were further associated with a reduction in violence on multivariate analysis. While the strongest single correlate of reduced violence at follow-up on multivariate analysis was violence at program entry, taken together, these results support targeting PTSD symptoms and substance use when seeking to reduce violence among veterans with PTSD. Intensive treatment may have benefited these patients either because medication and psychotherapy reduced violence directly or, more likely, because treatment reduced the PTSD symptoms and substance use that increased the risk of violence. Some symptom reduction, for instance in re-experiencing and avoidance, may reduce vulnerability to environmental triggers of violence among persons with PTSD. Other changes with treatment, for instance, reduced arousal and irritability, seem likely to improve resilience more generally.

Finally, the decline in violence was most strongly associated with reductions in irritability, suicidality, and re-experiencing and with total PTSD symptom scores. While this bivariate finding was not preserved on multivariate analysis, it lends some support to research linking these symptom clusters to violence and suggesting that PTSD symptoms have a cumulative effect on violence risk (4). Further analysis of the PTSD and substance use change measures showed a high level of intercorrelation (α=.75), suggesting that these change measures reflect a common underlying construct. Patients who drank in part to relieve the distress and arousal of PTSD may have abused alcohol less as these symptoms improved.

Several limitations require acknowledgment. First, because violent behavior is a major reason that individuals with PTSD seek and are admitted for treatment (11), the overall reduction in violence is likely to reflect, at least in part, regression to the mean. Within the overall reduction in violent behavior we have identified variables correlated with greater and lesser reductions. We sought to control for the effect of regression to the mean on these correlations by including violence at program intake as a covariate in the regression analyses. Doing so is not a substitute for an intervention study that randomly assigns patients to treatment and control groups, however. Conclusions regarding causality from these data must be correspondingly cautious.

Second, we have examined the reduction in violence following treatment in a heterogeneous set of programs that used a range of forms of psychotherapy and medication. Although there was also some consistency across sites (for instance, all of these programs provided daily treatment in an inpatient, residential, or day hospital setting to U.S. veterans of recent military service), future research should seek to distinguish the effects of specific therapies and program structures both on symptomatic improvement and on violence risk. Third, we used self-report as the basis of our violence measure. Confirming these reports with official records of arrest and conviction, as well as information from collateral sources, would increase the validity of the outcome measure.

Finally, only a subset of veterans with a diagnosis of PTSD receives mental health services from the VHA, and, of this subset, only a smaller subset receives intensive PTSD treatment. The generalizability of the findings to other kinds of trauma and to women is unknown. Some factors associated with being lost to follow-up, such as younger age, were also related to violence. Although these associations do not demonstrate a bias in our analyses, we cannot exclude the possibility that the results would have been different had follow-up data been collected for all patients.

Previous suggestions that clinical variables are relatively unimportant correlates of violent behavior among samples of persons with a mental disorder (23) are not supported by this study. Not all of the treatment variables that we studied were equally relevant however. Length of stay and perceived commitment to treatment were less strongly associated with a reduction in violent behavior than changes in other clinical phenomena, such as improvements in substance abuse and PTSD symptoms. Most of the significant correlations between violent behavior and clinical variables were no longer significant on multivariate analysis. This suggests that the clinical variables are strongly intercorrelated, a finding consistent with clinical experience.

The mean length of stay in these programs was 44 days. Despite the move away from long-term inpatient psychiatric treatment in the VHA (25) and elsewhere in the U.S. mental health system (26), patients may have experienced benefits not just from treatment but also from nonspecific factors such as shelter, support, and respite from the cumulative effect of life stresses. If so, the benefit of this support for reduced violence remained evident four months after discharge. The role of intensive residential or inpatient treatment has been downplayed in mental health care in recent years, largely for economic reasons. This study suggests that the benefits of specialized intensive PTSD treatment, perhaps in turn reflecting the broader benefits of “asylum,” should not be ignored.

In this study of U.S. veterans receiving intensive treatment for PTSD, reduction in violence during and after treatment was more strongly correlated with reductions in patients’ PTSD symptomatology and substance use than with incarceration history or with sociodemographic and biographical variables traditionally associated with violence. The results suggest that the support, shelter, and asylum that are part of intensive treatment are associated with reduced violent behavior and that such services play an important role in the spectrum of care for war-related PTSD.