Validation and reliability study of the Morning Stiffness Assessment Scale in Turkish population

The aim of this methodological and descriptive study was to conduct a validation and reliability study of the Morning Stiffness Assessment Scale in the Turkish population. The sample of the study consisted of 112 patients diagnosed with RA who applied to the internal medicine - rheumatology outpatient clinics of a university hospital and met the inclusion criteria. The research data were collected through face-to-face interviews using a 23-item personal information form questioning patients' sociodemographic and disease-related characteristics, Morning Stiffness Assessment Scale, Health Assessment Questionnaire, and VAS scale. Successively, language and scope validity, criterion and discriminant validity, and reliability analyses of the scale were performed. Descriptive statistical methods (number, percentage, mean, standard deviation), correlation analysis, T test, One Way ANOVA tests, Cronbach's alpha analysis, confirmatory factor analysis, and exploratory factor analysis were used for data analysis. The Content Validity Ratio value for scope validity criterion was found to be 1.00. It was determined that the item-total test correlation values of the scale ranged from 0.67 to 0.82. The Cronbach's alpha values for the sub-dimensions of the scale were calculated as follows; Cronbach's alpha coefficient for Characteristics of Morning Stiffness sub-dimension was 0.82, for Overall İmpact of Morning Stiffness was 0.91, and for the total scale was 0.92. It was observed that the Turkish version of the scale showed good fit with the original model, thus confirming the 2-factor structure of the scale. The Morning Stiffness Assessment Scale is a valid and reliable tool for measuring morning stiffness in RA patients in the Turkish population.