Development and Validation of the Youth Back Activity Questionnaire: A Measure of Function for Adolescents With Low Back Pain.

DESIGN

A psychometric study.

OBJECTIVE

To develop a reliable and valid patient-reported outcome measure to assess functional ability in adolescents with low back pain (LBP) using the Rasch model.

SUMMARY OF BACKGROUND DATA: LBP is quite common in adolescence. Currently, no method adequately measures the functional ability of adolescents with LBP. Widely used outcome measures for LBP are problematic in adolescents, with significant ceiling/floor effects.

MATERIALS AND

METHODS

Two hundred adolescents (15.4 ± 1.9 yr; 56% female) with LBP. This study was comprised of two parts: part 1: development of the Youth Back Activity Questionnaire (YouthBAQ) (n = 75), and part 2: psychometric evaluation of the newly designed YouthBAQ using the Rasch model (n = 125). Participants also completed the Oswestry Disability Index (ODI) and Micheli Functional Scale (MFS), data analysis: reliability and construct validity of the YouthBAQ were assessed using Rasch analyses. Correlations with the ODI and MFS were used to determine the convergent validity of the YouthBAQ.

RESULTS

Part 1: Based on the results of the Rasch analysis, 31 items were reduced to 14. Part 2: The 14-item YouthBAQ demonstrated good reliability and construct validity, with good item fit (>0.7 and <1.3), acceptable item hierarchy and spacing, response category functioning, unidimensionality (ratio >3:1), and local independence (<0.30). The MFS demonstrated unacceptable reliability (person reliability = 0.62) and was not compared against the YouthBAQ. The ODI demonstrated acceptable reliability (person reliability = 0.70) but poor construct validity among adolescents with LBP. The YouthBAQ demonstrated a moderate correlation with the ODI ( r = 0.4).

CONCLUSION

The YouthBAQ is a quick and easily understood measure of function with good validity and reliability in adolescents with LBP. The YouthBAQ is a more appropriate measure of functional ability than the ODI or MFS in this population.