Salivary inflammatory biomarkers as a predictor of post-traumatic stress disorder and depressive symptom severity in trauma patients: A prospective study

Background: Although post-traumatic stress disorder (PTSD) and depression screening are recommended for traumatic injury patients, routine screening is still uncommon. Salivary inflammatory biomarkers have biological plausibility and potential feasibility and acceptability for screening. This study tested prospective associations between several salivary inflammatory biomarkers (proinflammatory cytokines interleukin-1 beta, interleukin-6, tumor necrosis factor-alpha; and C-reactive protein), collected during hospitalization and PTSD and depressive symptoms at 5-month follow-up. Methods: Adult traumatic injury patients (N = 696) at a major urban Level 1 trauma center provided salivary samples and completed PTSD and depressive symptom measures during days 0-13 of inpatient hospitalization. At 5-month follow-up, 368 patients (77 % male, 23 % female) completed the Clinician-Administered PTSD Scale for DSM-IV and the Self-rated Inventory of Depressive Symptomatology. Analyses focused on a latent inflammatory cytokine factor and C-reactive protein at baseline predicting 5-month PTSD and depression symptom outcomes and included baseline symptom levels as covariates. Results: A latent factor representing proinflammatory cytokines was not related to 5-month PTSD or depressive symptom severity. Higher salivary CRP was related to greater PTSD symptom severity (beta = .10, p = .03) at 5month follow-up and more severity in the following depressive symptoms: changes in weight and appetite, bodily complaints, and constipation/diarrhea (beta's from .14 to .16, p's from .004 -.03). Conclusion: In a primarily Latine and Black trauma patient sample, salivary CRP measured after traumatic injury was related to greater PTSD symptom severity and severity in several depressive symptom clusters. Our preliminary findings suggest that salivary or systemic CRP may be useful to include in models predicting posttrauma psychopathology.