Post-traumatic stress disorder symptoms in United Nations peacekeepers: an examination of factor structure in peacekeepers with and without chronic pain

Recent factor analytic investigations of post-traumatic stress disorder in military veterans suggest that symptoms are best described by either a hierarchical 2-factor model or a 4-factor inter-correlated model. Other recent evidence suggests that post-traumatic stress disorder and chronic pain are intricately related; however, the nature of this relationship is not well understood. Factor analysis provides one method for clarifying this relationship. In study 1, we compared competing models of post-traumatic stress disorder symptom structure in a sample of 400 male United Nations peacekeepers using confirmatory factor analysis. Results indicated that both the hierarchical 2-factor and the 4-factor inter-correlated models provided good fit to the data. In study 2, the reliability of these models was assessed in 427 male United Nations peacekeepers with chronic back pain and 341 without. Group comparisons of the confirmatory factor analysis results revealed that the structure of the hierarchical 2-factor and 4-factor inter-correlated models both provided good fit to the data in both the chronic back pain and the group without. However, the structure of the models for the group with chronic back pain group differed in significant ways from that of the group without chronic back pain. Post-traumatic stress disorder symptoms in military veterans can be adequately conceptualized using either a hierarchical 2-factor or 4-factor inter-correlated model. Chronic pain has a minimal influence on overall factor structure. The hierarchical 2-factor model, while parsimonious, does not provide the degree of symptom detail provided by the 4-factor inter-correlated model. Implications for conceptualization of post-traumatic stress disorder symptoms for patients with chronic back pain and significant post-traumatic stress disorder symptomatology are discussed.