*3.3. DASS-21 Scale*

The mental health status of the respondents was measured using the Depression, Anxiety, and Stress Scale-21 Items (DASS-21) [40]. In the following study, a polish adaptation of the DASS-21 scale was used [41]. The DASS-21 is a shortened version of the original 42-item DASS created by Lovibond and Lovibond, and both of them are self-report scales designed to estimate the overall emotional distress of a respondent, as well as to assess and evaluate the scores of the depression, anxiety, and stress levels [42,43]. It has been proved that both of the DASS scales show a high internal consistency [44]. The DASS-21 is composed of a hierarchical factor structure that includes the three first-order factors (depression, anxiety, and stress), as well as one second-order factor (emotional symptoms) [45]. Such a designated scale is suitable for both clinical and non-clinical purposes. An advantage is that compared to DASS-42, a shortened version (DASS-21) requires less time to be fulfilled by the respondents, providing similar outcomes at the same time. The main difference between these scales is the fact that the DASS-42 scale is preferably chosen for clinical purposes, whereas the DASS-21 is primarily chosen for research purposes. To compare the results with the normative data and scientific publications in which the DASS-42 scale was used, the statistical results obtained from the DASS-21 should be multiplied by 2. Such a conversion provides the possibility to obtain the validity of the statistical results that are comparable to those that are obtained while applying the DASS-42, however, being less time-consuming and more legible for the respondents at the same time [46].

The DASS-21 scale consists of three major scales (depression, anxiety, and stress), among which, each of them contains 7 items. The depression scale evaluates the lack of interest, devaluation of life, hopelessness, dysphoria, anhedonia, inertia, and self-deprecation. The anxiety scale evaluates the general autonomic agitation, situational anxiety, and a subjective experience of anxiety, whereas the stress scale assesses the chronic non-specific arousal such as tension, irritability, and nervousness. Responses were structured by a

4-point Likert scale ranging from 0 ('does not apply to me at all') to 3 ('applies to me very much or most of the time'), with higher scores indicating more negative experience in the past week. The total score of the DASS-21 ranges from 0 to 63, whereas the score for each of the subscales ranges from 0 to 21. After multiplication by 2 for further analysis of the results, we obtained a DASS-21 total maximum score of 126 and scores for every subscale equal to 42. The division of the total score multiplied by 2 of the depression, anxiety, and stress subscale is presented in Table 1 [42].

**Table 1.** The severity labels used to describe the range of scores in the population of the DASS-21 multiplied by 2.


In our study, the alpha coefficients for the reliability of the depression, anxiety, stress, and full scale in the entire group were 0.95, 0.89, 0.96, and 0.94, respectively. The calculated values of Cronbach's alpha for individual scales indicated the high reliability of the used scale.
