Relationship Between Psychological Distress, Burnout and Work Engagement in Workers During the COVID-19 Pandemic: A Systematic Review

Objective: The psychological distress that the COVID-19 pandemic has produced has generated negative effects on workers, and in one way or another this has affected their work engagement within companies. The aim of this research was to assess the relationship between psychological distress, burnout and work engagement in workers during the COVID-19 pandemic. Methods: A systematic review was carried out following the PRISMA methodology, taking articles from the Scopus, Pubmed, and Web of Science databases from the beginning of the pandemic until November 2022. The methodological quality was assessed using the Joanna Briggs Institute (JBI) critical appraisal tools for non-randomised studies. Results: 24 articles were selected. All the articles found an association between psychological distress, burnout or other factors and work engagement. Conclusion: The COVID-19 pandemic has had an impact on work engagement and a negative relationship with psychological distress and burnout, hence the importance of companies taking measures to minimise levels of psychological distress and burnout.


INTRODUCTION
As the pandemic has progressed, some studies have dealt with its negative effects, specifically concerning the psychological impact it has had on workers from different areas worldwide (1)(2)(3)(4), as well as the impact that certain variables such as the type of work, organisational climate, among others, may have on workers (5). According to Matziari et al. (6), burnout and work engagement are psychological reactions that are developed when individual characteristics interact with job characteristics, and which are based on the Job Demands Resources Model (7). One of these variables is work engagement, which is defined as the relationship between work and the conviction of being able to perform it effectively. This variable in turn involves a series of dimensions such as vigour (high energy level), dedication (identification with the work), and absorption (concentration on the work) (8). In this sense, work engagement is an important part of the productivity development of companies, where high standards of job satisfaction, adequate satisfaction with family life, and sufficient self-perceived health are required (9).
The COVID-19 pandemic has in one way or another affected the work engagement of workers in general, as determined by studies carried out in different countries and work areas (10)(11)(12). Likewise, other factors may also influence work engagement such as sickness presenteeism (SP) (defined as continuing to perform duties in the workplace despite working below full capacity due to illness) (13), meaningful work (10), sleep quality (14), emotional intelligence (15), etc.
It should be noted that, during the pandemic, companies had to find alternative ways of doing work, in some cases shifting to teleworking or even modifying working hours. In other companies, they switched to mixed types of hiring, i.e., people working from home and people who had to go to the office despite the confinement that was implemented in most countries, and this situation could have also affected engagement (16)(17)(18).
Psychological distress can negatively affect work engagement. In a study on non-healthcare workers, it was found that there were statistically significant differences between people with and without psychological distress. However, workers with the highest percentages of psychological distress showed low levels for the subdimensions of work engagement (vigour, dedication, and absorption) (11). It should be taken into account that chronic interpersonal work-related stress or stressors can also trigger emotional exhaustion, cynicism, or detachment from work, which may lead to chronic stress or burnout (19).
Burnout can be a predisposing indicator for the development of social and mental disorders, especially important in those people who have a certain predisposition for psychological disorders, taking medications or committing suicide attempts, among others (20). Any change can generate a stressful situation, even increased in a context of uncertainty and complexity of approach. This psychological distress, persisted over time, can lead to burnout. This can be a major public health problem in which work, family, and society interrelate and in which an interdisciplinary and community approach is needed. In fact, during COVID-19, many workers have been particularly exposed to the disease, some have lost their jobs, and many have seen their working conditions changed, with the consequent mental impact that this entails (21). For example, in a longitudinal study conducted on a sample of 1,308 Finnish workers, an increase in psychological distress and technostress was found during the COVID-19 crisis especially derived from a change in the conditions of their work, being especially greater in young women (22). Similarly, some occupational groups such as cleaners or healthcare workers have seen their workload increased in a context of greater exposition to COVID-19, in order to address emerging needs in society (23). Other professional groups have had to modify their way of working (teleworking, change of destinations and functions, etc.) and others have been forced into unemployment or temporary unemployment (24).
The aim of this research was to assess the relationship between psychological distress, burnout and work engagement in workers during the COVID-19 pandemic through a systematic review based on the PRISMA methodology.

Study Design
A systematic review was conducted following the guidelines of the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement (25). To this end, the authors relied on a protocol to carry out this systematic review, which was registered in the International Prospective Register for Systematic Reviews (PROSPERO) of the University of York, with identification code CRD42022350318.

Search Strategy
The search was carried out in the Pubmed, Scopus, and Web of Science electronic databases, based on the keywords from the research question generated by following the PICOT strategy ( Table 1).
The Medical Subject Headings (MeSH) descriptors used were: Psychological Distress; Burnout; Work engagement; and COVID-19. In order to enlarge the scope of the search, synonymous terms were used to complete the search based on the MeSH descriptors, linked using the Boolean operators AND and OR ( Table 2). Table 3 shows the search strategy used, carried out on 5 November 2022, for each of the databases during the search process.

Selection Criteria
The following selection criteria were used to select the articles:

Inclusion Criteria
-Original articles published in English and Spanish. -Type: original articles.
-Articles measuring any of the following values and/or effects: level of burnout, level of depression, level of stress and work engagement, number of cases of professionals with depression, stress and/or anxiety, comparison of levels before vs. during the COVID-19 pandemic, and comparison by country/type of profession/service.

Exclusion Criteria
-Studies written in a language other than English and Spanish. -Population: unemployed people. -Studies of low scientific-technical quality after applying the quality assessment tool. -Articles that did not answer the research question and were not related to the objective of the review. -Typology: opinion articles, editorials and letters to the editor, systematic reviews, short communications, and case reports.

Data Collection and Extraction
Once the data extraction was completed, two authors were in charge of the selection process by independently following the established inclusion and exclusion criteria, eliminating duplicate studies, and selecting articles that could be included after reading the abstract and title. Subsequently, the same two authors reviewed the full text of the studies which were potentially eligible for inclusion in the review, reaching a consensus; discrepancies were resolved by a third author.

Assessment of Methodological Quality
After selecting the articles for the review, two reviewers independently determined the methodological quality of the selected studies using the Joanna Briggs Institute (JBI) of the University of Adelaide, Australia, critical appraisal tools for nonrandomised studies (26). This allowed assessing the methodological quality of the studies and determining the extent to which a study had avoided or minimised the risks of bias in its design, conduct, and/or analysis. The cross-sectional quantitative study versions were used (27) (8 items) with a cut-off point of 6 for inclusion in this review ( Tables 4, 5).

RESULTS
The initial search strategies identified a total of 704 references, which were screened according to the topic of this review. A total of 24 studies (5,10,11,15,(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47) were finally selected ( Figure 1). All the analysed studies were quantitative. Of the 24 studies, 18 were conducted in the first phase of the pandemic, i.e., from December 2019 to June 2020, and 6 were conducted based on data collected until August 2021. There were 13 of the 24 studies focused on healthcare workers, with 9,469 participants divided as follows: 6,707 were women, representing 71%. In addition, of these 13 studies, 9 were specifically focused on nurses. The remaining 11 studies were focused on general workers, including social workers, software developers, teachers, and service personnel. In 1 of the 11 studies, there were 1,038 participants, but no data by sex was offered. In the other 10 studies, there were 7,828 participants in total, of which 4,539 were women, representing 58% of the samples. Of the 24 articles, 11 were conducted in Europe and 8 in Asia, 1 in Africa, 1 in Oceania, and 3 in the Americas.

DISCUSSION
The aim of this review was to assess the relationship between psychological distress (stress or burnout) and work engagement during the COVID-19 pandemic. To do so, the levels of stress, burnout, and work engagement were analysed in the 24 selected studies, and other factors were added that also influence work engagement.
All the articles carried out their studies with full-time employees over 18 years of age, but it is important to highlight the participation of women, with 71% in the group of healthcare staff and more than 50% in the case of general workers. In the case of healthcare personnel, the cause could be that most of the articles focused on nurses, a position in which women stand out.
With regard to healthcare workers, a study conducted in China among 258 nurses and 61 physicians (30) analysed the negative impact of the COVID-19 pandemic and work commitment, and the results showed that they were negatively correlated, but that if the necessary training was provided, the perception of risk decreased and work commitment increased. In another study in the same country with 1,040 nurses, it was also found that work engagement was negatively correlated with stress and burnout, and that women had lower levels of work engagement than men, with 43.02 and 47.25, respectively (35), as in the study by Jia et al. (28). Although these are values of engagement considered at a moderate level, in this study the factors that influenced to obtain better levels of work engagement were: being between 31 and 40 years old, being married, having more than two children, having a master's degree, among others. Job stress and presenteeism had a significant negative impact on task performance, which is related to two of the three dimensions of work engagement, namely absorption and dedication. In a study also conducted in China, with 4,261 physician participants, moderate levels of work engagements were found (28). The factors that influenced these results were being between 41 and 50 years old, being married, and having university education. In these studies there was a negative correlation between psychological distress and work engagement, that certain socio-demographic factors could influence, such as sex, being married, age, or years of experience, and that the assistance and training that the organisation can offer were also determinants in reducing the perception of risk and, therefore, increasing work engagement.
Directing our vision towards healthcare workers, in a study conducted in the Netherlands on burnout and work engagement, no significant differences were found between men and women (29). However, residents who were on the COVID-19 area had higher levels of burnout than those who were not assigned to the COVID-19 patients, with 16% and 7.6%, respectively. This may be due to working conditions (workload and concurrence of negative events) and the emotional impact that the pandemic had, especially in the initial stages of it (48). Regarding work engagement, residents who were assigned to intensive care patients evidenced a higher impact of the COVID-19 pandemic on their daily routine. Yet, no differences were observed before and after    the pandemic for residents who did not care for COVID-19 patients, possibly due to a specific training programme for surgery and strict hygiene conditions, that may lead to the high level of enthusiasm among residents in that country (29). In Spain, a study on 92 nurses found that, despite the pandemic and its impact, work engagement was moderate to high, perhaps because this group of professionals was aware of the importance of their work (47). In the same country, the study carried out on 499 nursing staff participants revealed that work engagement was 34.80 and the participants with low levels of engagement had high levels of psychological distress 76.7% (33), which indicated a negative correlation between these two variables. Meanwhile, in Germany, in a study on 166 nurses, it was found that half of the participants had low levels of stress, during the COVID-19 pandemic (39). It is worth mentioning that the data in this study were taken up to May 2021, the second year of the pandemic, which may partly explain the high level of work engagement. Also, in a Dutch study on 162 intensivists, 98 men and 64 women, burnout levels were 5.1% and 12.5%, respectively, while work engagement was assessed at low, moderate, and high levels, with men reporting 43.9% and women 31%. Although burnout values were low, women had a higher level, and women's work engagement scores were better than men's (36). In the Netherlands and Germany, similar levels were found to another study conducted in nurses in Egypt, with low levels of psychological distress were found, and moderate to high work engagement, while in Spain the levels of distress were higher with respect to the results of these countries, and work engagement was moderate. It could be deduced then that the organisational systems of each country and the allocated resources in each hospital can also influence psychological distress and, therefore, the level of work engagement, in addition to other factors such as sex, age, or being married. In Mexico, there was a prevalence of high levels of work engagement, higher than levels of burnout, but this did not imply protection against burnout (46). The results regarding work engagement were very similar to those found in the United States (42), which may be explained by the fact that these two studies were conducted in the second year of the pandemic, by which time more was already known about how to cope with the pandemic. With regard to general workers, a study conducted in Ecuador on 2,161 general workers determined that 62.72% of the population had psychological distress, with women having higher levels (69.1% vs. 55%) (43). As shown by studies on healthcare workers, sex, age, having children or not, level of education, and being married are also factors that influence the results (49). In another study conducted in Spain on nonhealthcare workers, it was found that at low levels of engagement there were higher percentages of psychological distress (77.9%), and this same trend was observed both in the group of workers who worked away from home and among those who worked from home (11). Following this, a study conducted in the UK on 1,038 general workers (44), in line with a study conducted in New Zealand on 530 social workers (10), found that work engagement was an effective predictor of reduced burnout, cynicism, and feelings of reduced professional competence.
In general, results from several countries show that psychological distress (stress or burnout) does have a significant negative effect on work engagement. However, other factors such as presenteeism may also play a role (28). On its part, meaningful work is another factor that can influence work engagement (10) and understanding the needs of healthcare workers during a pandemic is critical to attracting and retaining them (42). On the other hand, mindfulness and the quantity and quality of sleep are also factors to be considered, as indicated by a study conducted in Wuhan, China and replicated in the UK with general workers. The results revealed that there was a positive relationship between the amount of sleep and work engagement (31). Emotional intelligence is another factor to analyse, and a study conducted with Spanish workers indicated that there was evidence of a significant direct effect of emotional intelligence on individual job performance, as well as a mediating effect regarding work engagement (15).
The present study offers a number of limitations. Firstly, it should be noted that articles that were only written in English or Spanish were included, which may have left out articles that met the rest of the inclusion criteria. Secondly, it is important to stress that 13 of the 24 articles focused on healthcare workers and the rest on general workers, yet working in administrative or service areas. Therefore, the results cannot be extrapolated to professions in other sectors such as manufacturing, construction, food, etc. The generalisation of the results of this review should be considered with caution, as the main data come from studies in different countries, with different instruments and methodologies.

Conclusion
Based on the articles reviewed, it can be concluded that psychological distress or stress levels do have a significant impact on work engagement, as does burnout. However, there are other influencing factors such as presenteeism, meaningful work, mindfulness, and even emotional intelligence. On the other hand, with respect to healthcare workers and despite the COVID-19 pandemic, the results concerning work engagement have been moderate to high, while the results regarding psychological distress (stress or burnout) do differ among countries.
To minimize stress levels and encourage work engagement, organizations must take actions to ensure safety in the work environment, for example, promoting strategies that enable employees to understand their contribution to the goals of the organisation, their impact on the care and wellbeing of others, and their own personal growth. In addition, the ability of institutions to allocate the necessary resources and information to cope with a health crisis can be crucial to ensure that despite the heavy workload that healthcare workers have in such situations, specifically nurses and healthcare professionals, satisfaction can be derived from what they do and, at the same time, this may become a protective factor against physical and psychological harm.

AUTHOR CONTRIBUTIONS
All the authors have intellectually contributed to the work, met the conditions of authorship, and approved its final version. This work is original and has not been previously published and is not under review by any other journal. This manuscript conforms to the ICMJE recommendations for the conduct, reporting, editing, and publication of scholarly work in medical journals.