The psychometric properties of the Pearlin Mastery Scale in persons living with restless legs syndrome

Introduction: Restless Legs Syndrome (RLS) is a neurological disorder characterized by an urge to move arms and legs, commonly combined with distress, pain and motor restlessness. It can cause fragmented sleep, daytime symptoms, and decreased quality of life. Pharmacological treatment can suppress symptoms, but not cure. When challenged with illness, people may turn to their inner psychological resources such as self-esteem and mastery. The Pearlin Mastery scale was developed to study stress and coping, is commonly used in people with chronic illnesses, however, not yet validated in people with RLS. Aim: The aim was to test reliability and construct validity of the Pearlin Mastery Scale in persons with RLS. Methods: A cross-sectional postal survey including the Pearlin Mastery Scale, Restless Legs Syndrome-6 Scale, Pittsburgh Sleep Quality Index and Patient Health Questionnaire was sent out to members (n = 1500) of the national RLS association and 788 (52.5%) agreed to participate. Data were analyzed using classical test theory, Confirmatory factor analysis and Rasch measurement theory analysis. Hypothesis testing for construct validity was done by bivariate correlation analyses. Results: Most respondents were women (65%), retired (71%) and had a mean-age of 70.8 years (SD 11.4). The 7-item version of the Pearlin Mastery Scale showed poor fit to the one factor model. After omitting the two positively worded items (i.e., item 4 and 6), the 5-item version was found to be unidimensional, with satisfactory internal consistency. However, all items showed considerable ceiling effects. No measurement variance was seen regarding age-groups or sex. Higher level of mastery was moderately correlated with less depressive symptoms but only weakly correlated to RLS-related sleep problems. Conclusion: The 5-item version of the Pearlin Mastery Scale is suggested to be used in persons with RLS due to its acceptable psychometric properties. The instrument could be applied as an outcome measure for behavioral change interventions aiming to support mastery in RLS.