The Balanced Inventory for Spinal Disorders: the validity of a disease specific questionnaire for evaluation of outcomes in patients with various spinal disorders.

STUDY DESIGN: A prospective validation study.

OBJECTIVE: To validate the Balanced Inventory for Spinal Disorders (BIS), a questionnaire concerning the extent to which pain affects perceived physical health, social life, mental health, and quality of life. The operational definitions of the items and the verbal descriptive scales were compared with corresponding items in the Short-Form 36 (SF-36), European Quality of Life Scale (EQ), and Oswestry Disability Index (ODI).

SUMMARY OF BACKGROUND DATA: In validation studies, scales that intend to measure the same variable are compared.

METHODS: The SF-36, EQ, ODI, and the BIS were filled in by 101 patients before surgical treatment. The comparisons were analyzed by statistical methods that take account of the nonmetric properties of ordered categorical data to obtain reliable results. The level of order-consistency between BIS and comparing items, when present, was calculated. The Spearman rank-order correlation coefficient was also calculated.

RESULTS: In the paired comparisons between the BIS pain scales and the other pain scales about 80% units more pairs were ordered than disordered, and the disorder was explained by the discriminating ability of the BIS back and leg pain items. The BIS and ODI items of limitation in walking were comparable, and the assessments of social limitations on the questionnaires were consistent; the disordered pairs being explained by different coverage of activities in the items. The assessments of physical and mental health on BIS were disordered, with the responses in SF-36 in favor of the BIS type of scale categories. The few items and response categories in the EQ did not discriminate the assessments.

CONCLUSION: The BIS assessments can be regarded as being a valid disease-specific questionnaire that provides interpretable information regarding the impact of back end leg pain on well-defined physical, social and mental aspects, and on the quality of life.