For decades confirmatory factor analysis (CFA) has been the preeminent method to study the underlying structure of posttraumatic stress disorder (PTSD); however, methodological limitations of CFA have led to the emergence of other analytic approaches. In particular, network analysis has become a gold standard to investigate the structure and relationships between PTSD symptoms. A key methodological limitation, however, which has significant clinical implications, is the lack of data on the potential impact of item order effects on the conclusions reached through network analyses.

The current study, involving a large sample (N = 5055) of active duty army soldiers following deployment to Iraq, assessed the vulnerability of network analyses and prevalence rate to item order effects. This was done by comparing symptom networks of the DSM-IV PTSD checklist items to these same items distributed in random order. Half of the participants rated their symptoms on traditionally ordered items and half the participants rated the same items, but in random order and interspersed between items from other validated scales. Differences in prevalence rate and network composition were examined.

The prevalence rate differed between the ordered and random item samples. Network analyses using the ordered survey closely replicated the conclusions reached in the existing network analyses literature. However, in the random item survey, network composition differed considerably.

Order effects appear to have a significant impact on conclusions reached from PTSD network analysis. Prevalence rates were also impacted by order effects. These findings have important diagnostic and clinical treatment implications.

Research of military personnel who deployed to the conflicts in Iraq or Afghanistan has suggested that there are differences in mental health outcomes between UK and US military personnel.

To compare the prevalence of post-traumatic stress disorder (PTSD), hazardous alcohol consumption, aggressive behaviour and multiple physical symptoms in US and UK military personnel deployed to Iraq.

Data were from one US (n = 1560) and one UK (n = 313) study of post-deployment military health of army personnel who had deployed to Iraq during 2007–2008. Analyses were stratified by high- and low-combat exposure.

Significant differences in combat exposure and sociodemographics were observed between US and UK personnel; controlling for these variables accounted for the difference in prevalence of PTSD, but not in the total symptom level scores. Levels of hazardous alcohol consumption (low-combat exposure: odds ratio (OR) = 0.13, 95% CI 0.07–0.21; high-combat exposure: OR = 0.23, 95% CI 0.14–0.39) and aggression (low-combat exposure: OR = 0.36, 95% CI 0.19–0.68) were significantly lower in US compared with UK personnel. There was no difference in multiple physical symptoms.

Differences in self-reported combat exposures explain most of the differences in reported prevalence of PTSD. Adjusting for self-reported combat exposures and sociodemographics did not explain differences in hazardous alcohol consumption or aggression.

Little research has been conducted on the factors that may explain the higher rates of mental health problems in United States National Guard soldiers who have deployed to the Iraq War.

To examine whether financial hardship, job loss, employer support and the effect of deployment absence on co-workers were associated with depression and post-traumatic stress disorder (PTSD).

Cross-sectional data were obtained from 4034 National Guard soldiers at two time points. All measures were assessed by self-report.

The four factors were associated with depression and PTSD, with variability based on outcome and time point. For example, job loss increased the odds of meeting criteria for depression at 3 and 12 months and for PTSD at 12 months; the negative effect of deployment absence on co-workers increased the likelihood of meeting criteria for PTSD, but not depression, at both time points.

The findings demonstrate that National Guard soldiers have unique post-deployment social and material concerns that impair their mental health.