We studied the risk factors for long-term treat ment of 400 patients with w
hiplash 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 lesio
ns. We evaluated the following risk factors: sex, age, degree of vehicle da
mage, 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 ol
der. Damage to more than half of the car was associated with a longer treat
ment. 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 longterm t
reatment for whiplash injury in Japan.