Background: Recently a clinical prediction rule (CPR) has been developed that identifies patients with neck pain who are likely to respond rapidly and dramatically to thoracic spine thrust manipulation and an active range of motion exercise. Although the initial predictor variables identified during the development of a thoracic spine manipulation CPR seem to have adequate face validity, there is no guarantee that these factors will persist in a different group of patients, even ones with similar characteristics as those used in the initial exploratory study.