We know that traumatic events occur quite often. We also know that most people are resilient, even though many survivors experience some distress in the direct aftermath of an event. Only a minority will develop longer-term stress symptoms. What are their characteristics? Who is ‘at risk’ after trauma? If we know the answer, we can target mental health care services to the survivors who are most in need.

In the last 30 years, more and more research has been published on predictors of posttraumatic stress. Mainly in adults, but also in children.

To synthesize findings in adult survivors, Brewin and colleagues (2000) combined 77 studies on risk factors for PTSD in a meta-analysis. Important to note, about one third of these studies was conducted in military samples. The authors summarized the information on 14 risk factors. The strongest and most consistent predictors were: trauma severity, lack of social support, and additional (posttrauma) life stress.

Three years later, Ozer and colleagues published a somewhat similar meta-analysis on 68 studies with adults (only 47 studies were included in both analyses; which shows again that much depends on the selection criteria one applies…). The most important predictors they found, were: perceived life threat, lack of support, peritraumatic emotions, and peritraumatic dissociation.

So while both groups of researchers found that factors closely related to the event and the person’s reaction were important, they did differ on the exact characteristics.  In addition, Brewin et al. found that demographics did not help much (no to small effects) in explaining posttraumatic stress, while Ozer et al. did not even start to analyse them. Social support, on the other hand, appears a consistently present predictor. And fortunately one we could do something about.

Regarding children, three meta-analyses have been published recently. Two of them focused on injury/illness and one included all types of traumatic exposure. The last one, conducted by our group, included a comparison of the three studies. Because our study is more recent, included more studies, and was more strict its analyses, I’ll describe our findings mainly, but having a look at the reviews by Kahana et al. and Cox et al. is certainly worthwhile. Their references are shown below.

We included 34 longitudinal studies that measured predictors within 3 months posttrauma and posttraumatic stress at 3 months or more. Just like in Brewin’s paper, we did not find large effects for demographic variables, but found support for more ‘proximal’ variables. Various forms of short-term distress in the children themselves as well as in their parents were quite strong predictors for longer-term child posttraumatic stress. Within children’s distress, their posttraumatic stress reactions at 1-3 months had the strongest effect. However, the difference with acute stress reactions (0-1 month) was very small, which did not support the current strategy of ‘watchful waiting’: the prediction did not get much better over time. Unfortunately, we could not include social support in our analyses, as the variable wasn’t studied often enough yet.

Meanwhile, a few tentative conclusions can be made. First, among the most predictive factors, there are a number on which we can intervene (I am assuming a causal effect), such as social support, posttrauma distress in children, and parental distress. Second, none of the factors explains a large part of later posttraumatic stress (the maximum was 31% of the stress reactions). We will probably need to work with combinations of factors. That wasn’t possible in a meta-analysis format yet for methodological reasons (not enough studies used the same sets of variables), but will hopefully be doable in the near future.

A final thought: it is interesting that we tend to focus on the characteristics of those people who have symptoms. We have put far less effort in understanding why someone is resilient. This is slowly changing though, and there are a number of researchers disentangling trajectories of recovery at the moment (e.g., Bonanno, Le Brocque). I think that will bring about important steps forward.

References

Brewin, C., Andrews, B., & Valentine, J. (2000). Meta-analysis of risk factors for posttraumatic stress disorder in trauma-exposed adults. Journal of Consulting and Clinical Psychology, 68 (5), 748-766 DOI: 10.1037/0022-006X.68.5.748

Ozer, E., Best, S., Lipsey, T., & Weiss, D. (2003). Predictors of posttraumatic stress disorder and symptoms in adults: A meta-analysis. Psychological Bulletin, 129 (1), 52-73 DOI: 10.1037/0033-2909.129.1.52

Kahana, S., Feeny, N., Youngstrom, E., & Drotar, D. (2006). Posttraumatic Stress in Youth Experiencing Illnesses and Injuries: An Exploratory Meta-Analysis Traumatology, 12 (2), 148-161 DOI: 10.1177/1534765606294562

Cox, C., Kenardy, J., & Hendrikz, J. (2008). A Meta-Analysis of Risk Factors That Predict Psychopathology Following Accidental Trauma Journal for Specialists in Pediatric Nursing, 13 (2), 98-110 DOI: 10.1111/j.1744-6155.2008.00141.x

Alisic, E., Jongmans, M., van Wesel, F., & Kleber, R. (2011). Building child trauma theory from longitudinal studies: A meta-analysis Clinical Psychology Review, 31 (5), 736-747 DOI: 10.1016/j.cpr.2011.03.001