title: Assessment of plasma C-reactive protein as a biomarker of posttraumatic stress disorder risk.
abstract: OBJECTIVE
  Posttraumatic stress disorder (PTSD) has been associated in cross-sectional studies with peripheral inflammation. It is not known whether this observed association is the result of PTSD predisposing to inflammation (as sometimes postulated) or to inflammation predisposing to PTSD.
  
  
  OBJECTIVE
  To determine whether plasma concentration of the inflammatory marker C-reactive protein (CRP) helps predict PTSD symptoms.
  
  
  METHODS
  The Marine Resiliency Study, a prospective study of approximately 2600 war zone-deployed Marines, evaluated PTSD symptoms and various physiological and psychological parameters before deployment and at approximately 3 and 6 months following a 7-month deployment. Participants were recruited from 4 all-male infantry battalions imminently deploying to a war zone. Participation was requested of 2978 individuals; 2610 people (87.6%) consented and 2555 (85.8%) were included in the present analysis. Postdeployment data on combat-related trauma were included for 2208 participants (86.4% of the 2555 included) and on PTSD symptoms at 3 and 6 months after deployment for 1861 (72.8%) and 1617 (63.3%) participants, respectively.
  
  
  METHODS
  Severity of PTSD symptoms 3 months after deployment assessed by the Clinician-Administered PTSD Scale (CAPS).
  
  
  RESULTS
  We determined the effects of baseline plasma CRP concentration on postdeployment CAPS using zero-inflated negative binomial regression (ZINBR), a procedure designed for distributions, such as CAPS in this study, that have an excess of zeroes in addition to being positively skewed. Adjusting for the baseline CAPS score, trauma exposure, and other relevant covariates, we found baseline plasma CRP concentration to be a highly significant overall predictor of postdeployment CAPS scores (P = .002): each 10-fold increment in CRP concentration was associated with an odds ratio of nonzero outcome (presence vs absence of any PTSD symptoms) of 1.51 (95% CI, 1.15-1.97; P = .003) and a fold increase in outcome with a nonzero value (extent of symptoms when present) of 1.06 (95% CI, 0.99-1.14; P = .09).
  
  
  CONCLUSIONS
  AND RELEVANCE A marker of peripheral inflammation, plasma CRP may be prospectively associated with PTSD symptom emergence, suggesting that inflammation may predispose to PTSD.
authors.affiliation: Department of Medicine, University of California, San Diego (UCSD)2Veterans Affairs (VA) San Diego Healthcare System, San Diego, California.
authors.forename: Satish A
authors.initials: SA
authors.lastname: Eraly
authors.affiliation: Veterans Affairs (VA) San Diego Healthcare System, San Diego, California3VA Center of Excellence for Stress and Mental Health, San Diego, California4Department of Psychiatry, UCSD, La Jolla.
authors.forename: Caroline M
authors.initials: CM
authors.lastname: Nievergelt
authors.affiliation: Department of Psychiatry, UCSD, La Jolla.
authors.forename: Adam X
authors.initials: AX
authors.lastname: Maihofer
authors.affiliation: Department of Preventive Medicine, University of Southern California, Los Angeles.
authors.forename: Donald A
authors.initials: DA
authors.lastname: Barkauskas
authors.affiliation: Department of Medicine, University of California, San Diego (UCSD).
authors.forename: Nilima
authors.initials: N
authors.lastname: Biswas
authors.affiliation: Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Agorastos
authors.initials: A
authors.lastname: Agorastos
authors.affiliation: Department of Medicine, University of California, San Diego (UCSD)2Veterans Affairs (VA) San Diego Healthcare System, San Diego, California.
authors.forename: Daniel T
authors.initials: DT
authors.lastname: O'Connor
authors.affiliation: Veterans Affairs (VA) San Diego Healthcare System, San Diego, California3VA Center of Excellence for Stress and Mental Health, San Diego, California4Department of Psychiatry, UCSD, La Jolla.
authors.forename: Dewleen G
authors.initials: DG
authors.lastname: Baker
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000378:metabolism*; D003130:Combat Disorders / Q000097:blood* / Q000175:diagnosis* / Q000523:psychology; D006801:Humans; D007249:Inflammation / Q000097:blood / Q000175:diagnosis / Q000523:psychology; D008137:Longitudinal Studies; D008297:Male; D008889:Military Personnel / Q000523:psychology*; D009483:Neuropsychological Tests; D011237:Predictive Value of Tests; D011446:Prospective Studies; D055500:Resilience, Psychological; D018570:Risk Assessment; D013313:Stress Disorders, Post-Traumatic / Q000097:blood* / Q000175:diagnosis* / Q000523:psychology
chemical_list: D015415:Biomarkers; D002097:C-Reactive Protein