Objective: Depression, anxiety, stress, and physical disabilities are a common complaint in people with multiple sclerosis (MS), and monitoring of these symptoms are based on self-report questionnaires. The objective of this study was to determine psychometric properties of the Croatian version of the Depression, Anxiety, and Stress Scale-21 (DASS-21) and Multiple Sclerosis Impact Scale-29 (MSIS-29) in people with MS.

Methods: We included data on 163 people with MS registered in the Association of multiple sclerosis societies of Croatia (AMSSC). Patients' demographic information, education level, and disease-related variables were ascertained. DASS-21 was applied for assessing depression, anxiety, and stress, while MSIS-29 scale was used for assessment of the physical and psychological impact of MS disease. Psychometric properties were examined by estimating the validity and reliability of the DASS-21 and MSIS-29 scale. Predictive validity of DASS-21 subscales and relevant demographic and disease-related variables was examined by the hierarchical regression model.

Results: The Croatian version of the three DASS-21 subscales and two MSIS-29 subscales had excellent internal consistencies (Cronbach's alpha coefficients 0.88-0.93) and good convergent validity, as expressed by inter-correlations between DASS-21 and MSIS-29 subscales. Hierarchical regression analysis using MSIS-29 subscales as criterion variables showed consistent evidence for the predictive validity of depression, anxiety, and stress on psychological impact, and predictive validity of age, EDSS, and anxiety on physical impact.

Conclusions: The Croatian versions of DASS-21 and MSIS-29 are reliable and valid scales in people with MS.