Responsiveness and interpretability of the Argentine version of the Pain Catastrophizing Scale in subjects with chronic low back pain

Abstract

Objective: To report the responsiveness and interpretability of the Argentine version of the Pain Catastrophizing Scale (PCS-Arg) in a sample of subjects with chronic low back pain (CLBP).

Materials and methods: A prospective, observational, and longitudinal study was conducted. Subjects with CLBP referred to the physical therapy unit of a public hospital in the Autonomous City of Buenos Aires were recruited. At baseline, demographic data and PCS-Arg scores, as well as pain intensity, disability, quality of life, and depression were recorded through self-reported questionnaires. In a second instance, at one month or discharge, the same variables were collected, along with a Global Rating Of Change (GROC) scale. Responsiveness was assessed using longitudinal construct validity. Interpretability was calculated using the anchor-based method, and the minimal clinically important difference (MCID), and substantial clinical benefit (SCB) were reported.

Results: A total of 102 subjects were included in the study. The PCS-Arg showed acceptable responsiveness. The MCID score was 10 points, with an area under the curve (AUC) of 0.65 and a confidence interval of 95 % (CI95% 0.47-0.83). The SCB score was 17 points, with an AUC of 0.66 (CI95% 0.55-0.77).

Conclusion: The PCS-Arg is a responsive instrument. The discriminative ability of the values to identify MCID and SCB was poor. These results will allow for interpreting the impact of different treatments aimed at targeting catastrophizing, as well as enhancing future clinical trials on subjects with CLBP.