Towards a specific outcome instrument for spinal trauma : How to measure function and health

Study Design. Validation study. Objective. To investigate the most valid, reliable, and comprehensible response scale for spinal trauma patients to compare their current level of function and health with their preinjury state. Summary of Background Data. In the context of a main project of the AOSpine Knowledge Forum Trauma to develop a disease-specific outcome instrument for adult spinal trauma patients, the need to identify a response scale that uniquely reflects the degree to which a spine trauma patient has returned to his or her preinjury state is crucial. Methods. In the first phase, 3 different question formats and 3 different response formats were investigated in a questionnaire, which was administered twice. Based on the results of the first phase, in the second phase, a modified questionnaire was administered once to a second group of patients to investigate 5 different response formats: 0–10 Numeric Rating Scale-11, 0–100 Numeric Rating Scale-101, Visual Analogue Scale, Verbal Rating Scale, and Adjective Scale. All patients were interviewed in a semistructured fashion to identify their preferences. Multiple statistical analyses were performed: test-retest reliability, internal consistency, and discriminant validity. Results. Twenty eligible patients were enrolled in the first phase and 59 in the second phase. The initial phase revealed the highest preference for 1 specific question format (60.0% and 86.7% after the first and second administration of the questionnaire, respectively). The second phase showed the Verbal Rating Scale as the most preferred response format (35.6%). The semistructured interviews revealed that overall, a subgroup of patients preferred a verbal response format (42.4%), and another group of patients preferred a numerical response format (49.1%). The statistical analysis showed good to excellent psychometric properties for all formats. Conclusion. The most preferred question and response formats were identified for use in a disease-specific outcome instrument for spinal trauma patients