A valid cross-culturally adapted simplified Chinese version of the Quebec Back Pain Disability Scale

Abstract

Objective: To evaluate the reliability and validity of the simplified Chinese version of the Quebec Back Pain Disability Scale (SC-QDS).

Study design and setting: The QDS was translated and cross-culturally adapted into SC following international guidelines. The SC-QDS was completed by 114 patients with low back pain (LBP) and 65 healthy controls, along with the SC Oswestry Disability Index (SC-ODI) and visual analogue scale (VAS). Psychometric evaluation included homogeneity and reproducibility by internal consistency and test-retest reliability and construct validity by calculating the Pearson's correlation coefficients among QDS, SC-ODI, and VAS. Discriminative validity was determined by student's t-test.

Results: SC-QDS scores were well distributed, with no floor or ceiling effects. Internal consistency was excellent (Cronbach α 0.976). The items and overall SC-QDS were correlated (r=0.640-0.898 and P<0.0001). Intraclass correlation coefficient of test-retest reliability was excellent (0.987, 95% confidence interval: 0.978-0.992). Construct validity was confirmed by high correlation of SC-QDS and SC-ODI (r=0.901 and P<0.0001) and VAS (r=0.770 and P<0.0001) scores, as was discriminative validity by significantly different SC-QDS scores for patients with LBP and controls (46.3 ± 19.9 vs. 14.6 ± 8.5 and P<0.0001).

Conclusions: The SC-QDS has good internal consistency, test-retest reliability, and construct and discriminative validity. The SC-QDS is appropriate for clinical and research uses with Chinese-speaking patients with LBP in mainland China.