Development and validation of the visual analogue scale (VAS) spine score

The aim of the study was the development and validation of a new subjective rating scale for assessment of outcome in patients with thoracolumbar frac tures and fracture dislocations. The VAS spine score consists of 19 score items, using 100-mm Visual analogu e scales. The items are answered by the patients independently of rater ass essment. To measure the analogue scales and calculate the score, a computer -aided system was evolved consisting of self-developed software and digitiz er board. The overall score is the mean of all items answered with values b etween 0 and 100. The individual score loss is calculated as the difference between the preinjury score and at follow-up with Values between 0 and 100 . The VAS spine score was tested for reliability with a group of 136 health y volunteers. We performed a test-retest study with an interval of 24 h. Fo r statistical analysis of the validity,we prospectively followed a group of 53 patients with the new outcome score. We chose patients with injuries of the thoracolumbar spine, all having been operatively treated by combined p osterior-anterior stabilization and fusion between 1994 and 1996. In the reference group,the average test score was 91.95 (58-100) and 92.10 (58-100) at retest. The mean individual difference between test and retest scored 1.037 (0-8). A high reliability was proved by a strong correlation w ith a coefficient of 0.976 (P < 0.001). A high internal consistency of the VAS spine score was shown by a Cronbach-alpha of 0.9117. The mean score for the preinjury status of the patients was comparable to the reference group , amounting to 89.60 (21-100). The mean score at the time of implant removal was significantly (p < 0.001) decreased to 58.25 (13-97). Until th e time of follow-up a significant (p <0.001) increase was noted, and the group scored 66.08 (15-100) at follow-u p. This was a significant (p < 0.001) difference compared with the preinjur y status. The individual score loss averaged 24.1 (0-80). In the patient gr oup we also noted a Cronbach-alpha > 0.95, indicating a high internal consi stency. With the VAS spine score the authors have inaugurated a new tool for outcom e measurement in the treatment of patients with thoracolumbar injuries. The study has proved the score to be both reliable and valid. The application of the score is helpful in analyzing the subjective outcome, and the result s can be correlated with objective measures. The score is a useful tool for comparative clinical studies, addressing the outcome after different metho ds of treatment.