Background and Aims:
12-month post-accident pain distribution demonstrates that although 60% of individuals are entirely pain-free, above 70% of painful individuals report moderate-severe levels (≥50), creating “all or nothing” pain dichotomy, one not seen at baseline.
Study aim - to determine if very-early acute pain-related personality features, pain modulation profile and clinical factors can explain this dichotomy. 
Methods:
117 post-MVC patients with an mTBI were recruited and followed for 1-year. Patients split into 4 groups based on 12m pain levels in head and/or neck: (1) 0,0 (2) 1-49 in one or both (3) ≥50 in one (4) ≥50 in both sites
Head pain, neck pain, number of painful body areas; static and dynamic QST measures, and questionnaires compiled within 72h post-accident. Pain scores collected again at 12m. 
Linear correlation performed for all groups, Mann-Whitney U Test performed between groups 1 and 4 to find explanatory factors for edge-group behavior.  
Results:
Linear correlation found for painful body areas (2.92±1.3, 2.85±1.2, 3.47±1.9, 3.82±1.2; p=.004), head ( 43.75±30.6, 39.9±20.8, 51.0±32.1, 67.6±25.0; p= .001) and neck (49.0±30.0, 48.1±25.5, 57.1±30.2, 67.9±24.1; p=.006) pain, and pain50 temperature(45.6±3.2, 45.0±3.6, 44.4±3.2, 43.7±3.0; p=.018)  and a trend for pressure-pain-threshold (3.3 ±2.0, 3.1±2.1, 2.9±1.4, 2.4±1.2; p=.054). 
Mann-Whitney found significant differences in: painful body areas (p=.004), head (p=.002) and neck (p=.014) pain, pain50 (p=.005), PPT (p=.032), depression (p=.020), and stress (p=.038). 
Conclusions:
Higher clinical pain, pro-nociceptive pain behavior, and psychological distress at baseline can predict pain non-recovery at 12m post-injury. 
Acknowledgment:
Supported by US Department of Defense, Health Affairs Office, No. W81XWH-15-1-0603

VERY-EARLY ACUTE CLINICAL PAIN, PSYCHOPHYSICAL PAIN SENSITIVITY AND PSYCHOLOGICAL DISTRESS CAN PREDICT PAIN BEHAVIOR IN MTBI POST-COLLISION PATIENTS AT ONE-YEAR POST-INJURY