Predictors of differential PTSD and depression symptom trajectories in firefighters: a growth mixture analysis

<b>Background:</b> Firefighters are considered to be high-risk professionals due to their frequent exposure to traumatic events. Although most firefighters will demonstrate resilience after trauma exposure, others develop symptoms of posttraumatic stress disorder (PTSD) or depressive symptoms. Insight in psychological predictors of these differential trajectories might inform the development of prevention programmes.<b>Objective:</b> To test the predictive validity of risk and protective factors for longitudinal trends of PTSD and depressive symptoms in firefighters using growth mixture modeling.<b>Method:</b> A total of 529 firefighters were followed for 3 years. Risk and protective factors (experiential avoidance, repetitive negative thinking (RNT), meaning in life, resilience and social support) as well as symptoms of PTSD and depression were assessed via self-report at the baseline assessment. PTSD and depressive symptoms were re-assessed over the following 3 years, with intervals of 6-12 months. Mixture growth models assigned individuals to latent classes for PTSD and depression symptoms separately. A 3-step approach was used to predict class membership by the included risk and protective factors.<b>Results:</b> Both for PTSD and depressive symptoms growth models, the 2-class solution showed the best fit. Experiential avoidance predicted both PTSD and depressive class membership, while RNT predicted only depressive class membership.<b>Conclusions:</b> Although the vast majority showed a generally stable low level of symptomatology, increased scores on experiential avoidance and RNT were associated with less favorable trajectories. Targeting these risk factors in prevention programmes might prevent development of posttrauma symptomatology and increase psychological resilience in firefighters and other high-risk professionals.