**2. Materials and Methods**

The study questionnaire, based on relevant literature, was created by neurologists and psychologists experienced in MS (Supplementary Materials). The following sections were included:


The participants were asked to report all the aspects of the pandemic burden experienced from March 2020 to the time of responding to the survey.

Perceived Stress Scale (PSS-10) [7] was introduced to measure a level of experienced stress and the shortened version of Coping Orientations to Problems Experienced (Brief– COPE) [8]—to evaluate coping strategies. Both tools were provided in the standardized Polish version [9].

PSS-10 [7,9] contains 10 items which refer to subjective perception of situations and problems within the preceding 4 weeks. Response to each item can be scored 0–4 and their sum makes the total score, ranging from 0 to 40. Higher score indicates greater level of perceived stress. According to a 10-degree sten scale, a total score within stens 1–4 reflects low level of stress, between 5 and 6 sten—moderate level, and above 7—high level of stress.

Brief-COPE [8,9] consists of 28 items, associated with 14 coping strategies. The response to each item is rated 1–4 and the average score is calculated for each coping strategy, indicating its utilization by the subject. Coping strategies can be also categorized into their main types.

The survey was conducted parallel through online and printed modes in August and September 2020. Computer-assisted web interviewing (CAWI), an Internet surveying technique in which the interviewee follows a script provided in a website, allowed to create Google Forms, with the link posted on the central website of Polish MS Society and throughout social media profiles of its regional divisions.

The printed version of the same questionnaire was freely distributed among the willing subjects visiting the two major outpatient clinics in Lower Silesia (south-western region of Poland). These subjects were informed about two eligible versions of survey and were requested to submit only one of them. Completed printed questionnaires were collected by medical assistants not involved in the research team. After six weeks the number of respondents to the online survey reached 128 and no new responses were recorded within the next two weeks. By then, 159 complete responses to the printed questionnaires had been collected and the database was closed.

The responses collected by CAWI method were downloaded, the responses from printed questionnaires were recorded as the text files and all the data were transferred into Microsoft Excel (Microsoft Corporation, Redmond, WA, USA) spread sheet for statistical analysis.

Mean values with standard deviation were calculated for PSS-10 and Brief-COPE scores, and the distribution of responses in particular categories was analyzed. Relationships were searched between PSS-10 and Brief-COPE results and other analyzed variables.

To select proper statistical methods, a normality of distribution for all continuous variables was verified with a Shapiro–Wilk test. For the majority of variables, an assumption of normal distribution was not met. Therefore, non-parametric tests were used for the analysis. Comparisons between two independent groups were performed with U Mann– Whitney test or t-Student test if the proper assumptions were met. In case of comparisons for which an independent variable was of a categorical type, a Kruskal–Wallis ANOVA rank test was applied. To assess the correlations, the Spearman rank correlation was applied. To assess the independence of categorical variables, Pearson Chi-square test was used. A *p*-value less than 0.05 was considered statistically significant. The statistical analysis was performed using STATISTICA PL v.8 statistical software (StatSoft, Kraków, Poland).

The project of the study was approved by Local Bioethical Committee at Wroclaw Medical University. Participation in the survey was voluntary and without any financial compensation. Anonymity of the responses was maintained throughout collection and storage of data. An informed consent form to participate in the study and allow procession of data for research purposes was provided in the initial part of the questionnaire. Its confirmation in the online version was necessary to proceed with responding to the questions and submit the filled questionnaire. In the printed version, consent was confirmed by signing the form and completion of the questionnaire.
