The Symptom Checklist: Frequency and Severity Scale – translation and psychometric properties of the Swedish version

The Symptom Checklist: Frequency and Severity Scale (SCL) is a symptom-specific questionnaire that measures the patient’s perception of the frequency and severity of arrhythmia-related symptoms. Worldwide, the SCL is one of the most used symptom-specific questionnaires for this purpose. Until now, there has not been a valid Swedish translation of the SCL. This study aimed to translate the SCL into Swedish and test the face, content and construct validity of the translated version. The questionnaire was translated using the WHO’s recommendations for translation. Using the ‘think aloud method’, we gathered data from 12 patients regarding the intelligibility of the questions. Using exploratory factor analysis (EFA), we evaluated the face validity, construct validity and internal consistency properties of the questionnaire. The study included 646 patients with different types of supraventricular tachycardia, atrial fibrillation (AF) atrial flutter (AFL), atrioventricular reentrant tachycardia (AVRT), atrioventricular nodal reentrant tachycardia (AVNRT), and ectopic atrial tachycardia (EAT). Translation and face validity were found to be acceptable. Construct validity evaluated using EFA and principal component analysis with varimax rotation identified four factors with eigenvalues greater than 1 and factor loading equal to or greater than 0.364, accounting for 58% and 53% of the variance in the frequency scale and the severity scale, respectively. Reliability evaluation revealed high internal consistency. For both the frequency and severity scale, the Cronbach’s alpha coefficient was 0.88. Our results show evidence that the Swedish version of the SCL has good psychometric properties according to face and construct validity and internal consistency for patients with AF, AFL, AVRT, AVNRT and EAT, and is reproducible and valid.