Psychometric Properties of the PCS and the PCS-4 in Individuals With Musculoskeletal Pain.

BACKGROUND: The factor structure of the Pain Catastrophizing Scale (PCS) has rarely been adequately analyzed (e.g., performing principal component analyses rather than factorial approximations). We aimed to evaluate the psychometric properties of the PCS through a variety of exploratory and confirmatory factorial approaches. METHOD: Three hundred ninety-four Chilean patients with musculoskeletal pain were included (age, M = 49.61, SD = 18.00; 71.57% women). Eight factorial models were proposed to analyze the structure of the data. In addition, validity evidence of the PCS based on relationships with other variables were analyzed considering pain intensity and kinesiophobia. RESULTS: The results suggest a unidimensional structure. Models with more than one dimension exhibited undesirable factor loadings or inadequate indices of fit. Based on these results, a short version of the scale composed of 4 items is proposed (PCS-4). The PCS-4 scores demonstrated high levels of invariance between sex, chronicity, and education groups and also were associated with pain and kinesiophobia. CONCLUSIONS: The results of the PCS-4 Spanish version showed evidence of reliability and validity for adequately measuring pain catastrophizing in Chileans who suffer from musculoskeletal pain. The PCS-4 is a short form that should be explored in future studies (e.g., in other Spanish-speaking populations).

The Effect of Sleep Quality on Pain in Chilean Individuals with Musculoskeletal Disorders.

Poor sleep quality (SQ) negatively affects pain associated with musculoskeletal disorders (MSD). As the level of economic development of a country determines its sanitary conditions, these can influence the sleep-pain relationship; therefore, it is relevant to generate evidence in the population with MSD in developing countries. This cross-sectional study sought to determine the effect of poor SQ on pain in Chilean individuals with MSD, controlling for sex and duration of pain (in months). METHOD: A total of 228 individuals were included. SQ was measured with the Pittsburg Sleep Quality Index (PSQI), pain (intensity, interference and distress relative to pain) was measured with visual analog scales. Structural equation modeling (SEM) was performed to analyze the effect of SQ on pain. RESULTS: A high frequency of poor SQ was present in the studied group, and was more prevalent in women. The SEM model evidenced that poor SQ predicts greater pain. Sex influences sleep quality and pain, but not pain duration. CONCLUSIONS: These findings indicate that poor SQ predicts higher pain in MSD and that women exhibit worse SQ and more significant pain than men. Our findings support that SQ should be considered in the comprehensive approach to pain in individuals with MSD.