Confirmatory factor analysis of the Tampa scale, for Kinesiophobia - Invariant two-factor model across low back pain patients and fibromyalgia patients

Objectives: (1) To investigate the factor structure of the Tampa Scale for Kinesiophobia (TSK) in a Dutch-speaking sample of chronic low back pain (CLBP) patients using confirmatory factor analysis, (2) to examine whether the internal structure of the TSK extends to another group of fibromyalgia (FM) patients, and (3) to investigate the stability of the factor structure in both patient groups using multi-sample analysis. Patients and Methods: TSK-data from 8 studies collected in Dutch and Flemish chronic pain patients were pooled. For 188 CLBP patients and 89 FM patients, complete data were available. Confirmatory factor analyses were performed to assess 4 models of kinesiophobia, and to examine which factor model provided the best fit. Furthermore, a multi-sample analysis was performed to investigate the stability of the factor structure in both patient groups. Results: For both CLBP and FM patients, the 2-factor model containing the factors "activity avoidance" and "pathologic somatic focus" was superior as compared with the 4-factor model containing the factors "harm," "fear of (re)injury." "importance of exercise," and "avoidance of activity". Moreover, the 2-factor model was found to be invariant across CLBP and FM patients, indicating that this model is robust in both pain samples. Discussion: As the 2-factor structure provided the best fit of the data in both patient samples, we recommend to use this version of the TSK and its 2 subscales in both clinical practice and research. Based on the content of the items, the subscales were labeled "Harm" and "Fear-avoidance".