Development and Validation of Short Forms of the Pain Catastrophizing Scale

Purpose: Chronic pain is a complex phenomenon. Understanding its multiple dimensions requires the use of a combination of several patient-reported outcome measures (PROMs). However, completing multiple PROMs is time-consuming and can be a burden for patients. The objective of our study was to simultaneously reduce the French versions of the Pain Catastrophizing Scale (PCS) and Tampa Scale for Kinesiophobia (TSK) questionnaires to enable their use in an ambulatory and clinical settings. Patients and Methods: We conducted a clinical study between May 2014 and August 2020 in our rehabilitation center. 1428 chronic musculoskeletal pain patients (CMSP) were included. The originality of our approach is that the reduction method included qualitative as well as quantitative analyses. The study was divided into two parts: 1) reduction of the questionnaires (n=1363) based on internal consistency (item-to-total correlation), principal component analysis (item loadings), Rasch analysis (infit/outfit), floor and ceiling effect (quantitative analyses) and expert judgment of items (qualitative analysis), and 2) validation of the reduced questionnaires (n=65), including test--retest reliability (intraclass correlation coefficient [ICC]), homogeneity (Cronbach a), criterion validity (Pearson correlation [r] with the long-version score), determination of the pathological cutoff and Minimal Clinically Important Difference (MCID). The two full-length questionnaires include 30 items in total. Results: The reduction resulted in a 5-item PCS (score 0-20) and 6-item TSK (score 0-24). Psychometric properties of the reduced questionnaires were all acceptable as compared with other version (a=0.89 and 0.71, ICC=0.75 and 0.60, r=0.86 and 0.70, MCID=2 and 2 for PCS and TSK, respectively) while keeping the structure and coherence of the long versions. Conclusion: The two reduced versions of the PCS and TSK can be used in CMSP patient. As their administration only requires a few minutes, they can be implemented in outpatient consultation as well as in clinical settings. Keywords: chronic musculoskeletal pain, CMSP, patient-reported outcomes measures, PROMs, Pain Catastrophizing Scale, PCS, Tampa Scale for Kinesiophobia, TSK