Risk factors for long-term treatment of whiplash injury in Japan: analysis of 400 cases.

We studied the risk factors for long-term treatment of 400 patients with whiplash injury in Japan. Most of the patients were injured in rear-end car collisions, but none had cervical bone lesions or spinal cord or root lesions. We evaluated the following risk factors: sex, age, degree of vehicle damage, and admission or non-admission to the hospital. The group of patients younger than 20 years old healed more quickly than patients 30 years or older. Damage to more than half of the car was associated with a longer treatment. Patients who were admitted to the hospital need treatment longer than the non-admission group. Thus, age over 30 years, a large amount of damage to the vehicle, and admission to the hospital are predictors of long-term treatment for whiplash injury in Japan.