Pre-collision Medical Diagnoses Predict Chronic Neck Pain Following Acute Whiplash-trauma.

OBJECTIVES: The reason why some individuals develop chronic symptoms, whiplash-associated disorder, following whiplash trauma is poorly understood. We explored whether pre-collision pain-related diagnoses, medically unexplained symptoms and psychiatric diagnoses are related to whiplash-associated disorder.

METHODS: A cohort of 719 individuals exposed to whiplash trauma and subsequently experiencing symptoms within 72 hours (whiplash-exposed cohort) and 3595 matched controls were included in this observational prospective study. At 12 months post-collision, the whiplash-exposed cohort rated their neck pain using the Visual Analogue Scale. Data on health were obtained from the Danish National Patient Register for the whiplash-exposed cohort and for the controls for a five-year period prior to collision.

RESULTS: The whiplash-exposed cohort had significantly increased incidences of pre-collision pain-related diagnoses: χ(1) = 17.42, P <0.001 and medically unexplained symptoms: χ(1) = 22.2, P <0.001 but not psychiatric diagnoses: χ(1) = 3.60, P >0.05 compared to controls in the five-year period. Participants from the whiplash-exposed cohort with pre-collision pain-related diagnoses (OR = 2.46 [95 % CI = 1.39; 4.35]) and medically unexplained symptoms (OR = 1.72 [95 % CI = 1.04; 2.84]) had significantly increased odds for neck pain at follow-up.

DISCUSSION: Pre-collision pain and medically unexplained symptoms predict chronic neck pain following whiplash trauma. This may indicate that a sensitization process was initiated prior to the collision or that individuals with pre-collision low threshold for contacting health care services maintain this behavior post-collision. The collision may trigger existing individual vulnerabilities which constitute a risk factor for chronic whiplash.