Measuring the impact of multiple sclerosis on psychosocial functioning: the development of a new self-efficacy scale

Abstract

Objective: To develop a scale to measure self-efficacy in neurologically impaired patients with multiple sclerosis and to assess the scale' s psychometric properties. Design: Cross-sectional questionnaire study in a clinical setting, the retest questionnaire returned by mail after completion at home. Setting: Regional multiple sclerosis (MS) outpatient clinic or the Clinical Trials Unit (CTU) at a large neuroscience centre in the UK. Subjects: One hundred persons with MS attending the Walton Centre for Neurology and Neurosurgery and Clatterbridge Hospital, Wirral, as outpatients. Methods: Cognitively impaired patients were excluded at an initial clinic assessment. Patients were asked to provide demographic data and complete the self-efficacy scale along with the following validated scales: Hospital Anxiety and Depression Scale, Rosenberg Self-Esteem Scale, Impact, Stigma and Mastery and Rankin Scales. The Rankin Scale and Barthel Index were also assessed by the physician. Results: A new 11-item self-efficacy scale was constructed consisting of two domains of control and personal agency. The validity of the scale was confirmed using Cronbach' s alpha analysis of internal consistency (α = 0.81). The test–retest reliability of the scale over two weeks was acceptable with an intraclass correlation coefficient of 0.79. Construct validity was investigated using Pearson' s product moment correlation coefficient resulting in significant correlations with depression (r = –0.52) anxiety (r = –0.50) and mastery (r = 0.73). Multiple regression analysis demonstrated that these factors accounted for 70% of the variance of scores on the self-efficacy scale, with scores on mastery, anxiety and perceived disability being independently significant. Conclusion: Assessment of the psychometric properties of this new selfefficacy scale suggest that it possesses good validity and reliability in patients with multiple sclerosis. Address for correspondence: SJ Smith, Astley Ainslie Hospital, 133 Grange Loan, Edinburgh EH9 2HL, Scotland, UK.