Tehran University of Medical Sciences Journal of Modern Rehabilitation 2538-385X 17 3 2023 07 01 273 278 Mohsen Abedi Physiotherapy Research Center, Department of Physiotherapy, School of Rehabilitation, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Farshad Okhovatian Physiotherapy Research Center, Department of Physiotherapy, School of Rehabilitation, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Aliyeh Daryabor Physiotherapy Research Center, Department of Physiotherapy, School of Rehabilitation, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Alireza Akbarzadeh Baghban Proteomics Research Center, School of Allied Medical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran. 2021 08 31 2021 12 07 Introduction: Some accurate tools exist to assess fear-avoidance behavior, such as the Tampa scale for kinesiophobia (TSK) in individuals with musculoskeletal problems. The current research aims to compare the psychometric characteristics of the original 17-items TSK questionnaire and its 11-item brief version in chronic non-specific low-back pain (CNSLBP). Materials and Methods: In this test development study, 295 patients with CNSLBP referred to the physiotherapy clinic of Milad Hospital in Tehran city, Iran were evaluated. Confirmatory factor analysis (CFA) and α Cronbach was conducted to assess the validity and reliability of the original and brief version of the TSK, respectively. For goodness-of-fit, the Χ2/df, root mean square error of approximation (RMSEA), goodness-of-fit index (GFI), and comparative fit index (CFI) indices were used. Results: Internal consistency specified by Cronbach’s α was 0.949 for the original version of the questionnaire and 0.927 for the brief one. Based on the CFA findings, the goodness-of-fit indices for the brief version were GFI=0.921, RMSEA=0.078 (90% confidence interval (CI), 0.062%-0.094%), comparative fit index (CFI)=0.981, and Χ2/df=2.791. These indices for the original one were 0.882, 0.066 (90% CI, 0.055%-0.076%), 0.983, and 2.270, respectively. A significant correlation was found between these two versions (P<0.001). These findings confirm the adequacy of the brief version of the TSK. Conclusion: The brief version of TSK can be considered a reliable and valid tool to evaluate somatic focus and activity avoidance in patients with CNSLBP. https://jmr.tums.ac.ir/index.php/jmr/article/view/536