RESUMEN
PURPOSE: To identify the best internal structure of the Tampa Scale for Kinesiophobia in chronic low back pain patients. DESIGN: Questionnaire validation study was designed for this study. SETTING: This study was conducted in physical therapy facility. SUBJECTS: Respondents reporting chronic low back pain (≥3 points on the 11-point Numerical Pain Rating Scale). MAIN MEASURES: We included participants of both sexes, with a self-report of low back pain ≥3 months and with pain intensity ≥3 on the 11-point Numerical Pain Rating Scale; participants also answered the Roland-Morris Disability Questionnaire and the Pain-Related Catastrophizing Thoughts Scale for low back pain disability and catastrophizing, respectively. The dimensionality and number of items of the Tampa Scale for Kinesiophobia were evaluated using the confirmatory factor analysis. Criterion validity was assessed using Spearman's correlation coefficient using the original version of the 17-item Tampa Scale for Kinesiophobia as the gold standard. RESULTS: A total of 122 participants were included, with mean values of low back pain duration ≥48 months, pain intensity >5 and disability >8. Tampa Scale for Kinesiophobia structure with two domains and nine items was the most suitable, with adequate values in all fit indices (Chi-square/degree of freedom <3, Comparative Fit Index and Tucker-Lewis Index >0.90, and root mean square error of approximation <0.08) and lower Akaike information criterion and Bayesian information criterion values. We observed a high correlation between the 17-item Tampa Scale for Kinesiophobia and the activity avoidance domain (rho = 0.850, P < 0.001) and somatic focus domain (rho = 0.792, P < 0.001) of the nine-item Tampa Scale for Kinesiophobia. CONCLUSION: Tampa Scale for Kinesiophobia structure with two domains (activity avoidance and somatic focus) and nine items is the most suitable for patients with chronic low back pain.