Article Text

Effects of interventions implemented by occupational health professionals to prevent work-related stress complaints: a systematic review
  1. Suzanne Orhan Pees1,2,
  2. Sandra van Oostrom1,
  3. Hanneke Lettinga1,2,
  4. Frederieke Schaafsma2,
  5. Karin Proper1,2
  1. 1 National Institute for Public Health and the Environment, Bilthoven, Netherlands
  2. 2 Amsterdam UMC Locatie AMC, Amsterdam, Netherlands
  1. Correspondence to Dr Suzanne Orhan Pees, National Institute for Public Health and the Environment, Bilthoven, Netherlands; suzanne.pees{at}rivm.nl

Abstract

Work-related stress complaints are a growing societal problem. Occupational health professionals often play a key role in its prevention. However, studies providing an overview of preventive interventions and their effectiveness are lacking. Therefore, the aim of this systematic review was to summarise the evidence on the effectiveness of interventions delivered by occupational health professionals to prevent work-related stress complaints.

A systematic search in PubMed, Embase, PsycInfo and Medline was performed in May 2023 based on PICO (population, intervention, control and outcomes) elements. Inclusion criteria were: peer-reviewed papers with a randomised controlled trial design, quasi-experimental design and pre-post evaluations with a control group; working populations not on sick leave; interventions delivered by occupational health professionals; and stress outcomes. Data were extracted using a predefined extraction form, risk of bias was assessed using the Cochrane risk of bias tool for randomised trials (RoB-2) and Risk of Bias in non-randomised Studies-of Interventions tool, and a narrative analysis was performed to summarise data.

Nine studies were included in this review and encompassed a diverse range of populations, interventions and professionals involved, outcome measures, and effects observed. Five studies found either mixed effects on stress outcomes, short-term positive effects, or positive effects in a subgroup of participants demonstrating high adherence to the intervention.

As the results show mixed findings, a high risk of bias, and a limited number of studies was available, more research is needed to the effectiveness of the interventions and the factors underlying this.

  • Occupational Health
  • Occupational Stress
  • Mental Health
  • Burnout
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WHAT IS ALREADY KNOWN ON THIS TOPIC

  • Work-related mental health problems are a pressing public health concern, in which occupational health professionals can play a crucial role by providing preventive interventions. Yet, the existing evidence about the effectiveness of these interventions is scarce.

WHAT THIS STUDY ADDS

  • In this systematic review assessing interventions by occupational health professionals to prevent work-related stress complaints, mixed results were found, with four studies showing no significant effects and five demonstrated mixed or short-term positive effects. These results suggest that interventions with higher intensity tend to be more effective.

HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICY

  • The review highlighted the need for longer-term assessments, a standardised outcome set for stress measures, and increased focus on organisational interventions to address workplace culture and systemic factors influencing stress and burnout.

Introduction

Work-related mental health problems are a significant and growing public health concern. In 2020, in the European Union, 18.6% of all reported work-related health problems were due to mental health problems.1 These health complaints not only affect the psychological and emotional well-being of workers, but also influence work performance and productivity, work ability and absenteeism, and healthcare costs.2 The majority of countries have contracted the services of occupational health professionals and providers in order to promote and protect workers’ health, prevent (long-term) sickness absence and improve organisational performance.3 4 Of the 58 countries active in the International Commission on Occupational Health, the majority of occupational health services (OHS) offers mixed services, with both preventive and curative occupational healthcare, while one-third only offer preventive care.3 For the protection and promotion of workers’ mental health, occupational health professionals often play a crucial role in these systems by, among others, offering health surveillance, health assessments and health consultations, identifying psychosocial risk factors, offering support and resources for workers experiencing mental health challenges, or by implementing preventive interventions.3 5 Thus, occupational health professionals have the competencies necessary to support both individual workers to remain healthy and productive at work, as well as providing advice and support to employers in organising a healthy workplace culture.5

Several previous systematic reviews have been carried out with the purpose of examining the effects of activities or interventions preventing work-related mental health complaints. However, the majority of these studies focus on interventions in which occupational risk factors (eg, job demands, work attitudes, social support6 7) are not taken into account. Examples are physical exercise interventions,8 mindfulness interventions9–11 and (preventive) care delivered outside of occupational healthcare, such as interventions carried out in primary healthcare,12 or provided online (ie, e-health interventions).13–15 While these interventions show potential in improving mental health and reducing stress symptoms, the link with the specific work context is often lacking and important causes for work-related stress and burn-out can easily be missed and sustained. Involving an occupational health professional with knowledge of both work (psychosocial risk factors) and (mental) health in the implementation of preventive interventions could therefore be valuable. Therefore, the aim of this review was to summarise the evidence on the effectiveness of preventive interventions carried out by occupational health professionals and targeting work related stress complaints.

Methods

Study design and search strategy

This systematic review is reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.16 17 A systematic literature search was developed in collaboration with a librarian and tested with two researchers. The search strategy was then finalised and applied to the online libraries PubMed, Embase, PsycInfo and Medline on 2 May 2023, and repeated on 13 August 2023. The final search strategy was based on an iterative process of scanning papers for key terms, and included the following terms: worker; employee; work; workplace; prevention; intervention; occupational; occupational health; occupational physician (OP); occupational health service; occupational health nursing; occupational medicine; physiological stress; burnout; psychological well-being; distress syndrome; job stress; mental health; randomised controlled trial (RCT); controlled study; Dutch; English, and combinations of these terms. After the initial selection of papers, the reference lists of included studies and related reviews found during the search were checked for additional studies by means of snowball sampling. Additionally, handsearching was conducted in Google Scholar and the Cochrane Library for additional articles and reviews on the topic of the current review, and relevant papers have been extracted from those.

Eligibility criteria

Papers from all publication years were taken into consideration for inclusion if published in peer-reviewed journals and written in English or Dutch. Studies were eligible in case of RCTs, quasi-experimental designs (non-randomised, but controlled) and pre-post evaluations with a control group. Eligibility of the studies was assessed according to the PICO system: population, intervention, control and outcomes.

  • Population: the study population had to involve the working population not on sick leave.

  • Intervention: the intervention had to be delivered by an occupational health professional . Because of the differences in (occupational) healthcare systems between countries, a wide variety of professionals could deliver the intervention provided that they were labelled with ‘occupational health’ or ‘occupational medicine’. Studies that evaluated an intervention aimed at universal, selective and indicated prevention were considered for inclusion, and both interventions targeting the individual worker as well as the organisation were included.

  • Control: studies with a control group, that is, workers who did not receive an intervention by occupational health professionals (no intervention or a minimal intervention, or care as usual), were included.

  • Outcomes: studies were considered for inclusion if they used (self-reported) work-related stress complaints as outcome measure. This includes distress, work-related fatigue and burnout.

Selection of studies

After the search was carried out, the EndNote library was exported into the online screening software Rayyan to screen titles and abstracts (step 1) and full text (step 2).18 Using the integrated duplication detection tool, duplicates were identified and removed. Next, the screening and selection of papers was performed based on the inclusion criteria by one researcher (SOP) and checked by a second researcher (HL). In case of doubt about eligibility based on title and abstract, the article was selected for full-text screening. For RCT protocols, associated effect evaluation papers were searched. Next, the full articles were screened to make the final selection. If it was not clear from the article who delivered the intervention, the article was excluded. When in doubt about eligibility, authors were emailed to solve any unclarity or the study was discussed with the research team until agreement was reached. The PRISMA flow diagram of the selection of studies is depicted in figure 1.

Figure 1

Preferred Reporting Items for Systematic Reviews and Meta-Analyses flow diagram depicting the flow of included and excluded studies. *Records identified from online libraries PubMed, Embase, PsycInfo and Medline. **Records were excluded by hand.

Data extraction

Relevant data were extracted from the included articles into an Excel sheet by one researcher (SOP), using a predefined extraction format. This format included the following information: study characteristics (authors, year of publication, title, country), study design, PICO elements (study population, description of the intervention and control, and outcome measures), occupational health professional involved, number of participants, data collection and unit of measurement, main results, and conclusions. Short-term outcomes were defined by the research team as outcomes measured up until 1 year after baseline, whereas long-term outcomes were measured after more than 1-year follow-up. Unclarities were discussed and solved within the research team.

Risk of bias

The risk of bias of included studies was assessed by two researchers independently (SOP and SvO) and then discussed. For randomised trials, the revised Cochrane Risk of Bias tool (RoB-2) was used.19 Five domains were assessed as either low risk, some concerns, high risk or unclear. With regard to ‘Bias due to deviations from intended interventions’, questions regarding the effect of assignment to intervention were included in the assessment to assess the ‘intention-to-treat effects’.20

For non-randomised trials, the Risk of Bias in non-randomised Studies-of Interventions tool (ROBINS-I) was used.21 Seven domain were judged as having a low, moderate, serious or critical risk of bias.22 Questions or disagreements arising from the risk of bias assessment were discussed within the research team. An explanation for the domains of bias and their signalling questions can be found in table 1.

Table 1

Domains of the RoB-2 and ROBINS-I tool used to assess risk of bias of included studies

Analysis and interpretation of results

Because of the methodological diversity of the studies and the wide variety of the effect measures used, it was not possible to pool the data and/or to perform a meta-analysis. As an alternative, a qualitative narrative analysis was employed to identify and analyse common themes and patterns across the data of the selected studies.23 This was done by describing the key findings of the studies, grouping the studies based on type of intervention (ie, universal, selective or indicated), identifying consistencies and differences between findings, and summarising insights gained from this.23

Results

Selection of studies

The systematic literature search in online databases yielded a total of 972 papers (figure 1). After removing duplicates, titles and abstracts of 921 papers were screened and 878 papers were excluded since they did not fulfil the inclusion criteria. A total of six papers met the inclusion criteria and were included in the analysis of results. After performing additional handsearching and snowball sampling, three more papers were included, resulting in a total of nine studies included in our review.

Study characteristics and synthesis of findings

The included studies consisted of five RCTs24–28 and four studies with a quasi-experimental design (controlled, non-randomised).29–32 Interventions under study consisted of (combinations of) cognitive behavioural interventions or stress management training (N=4), consultations with or screening performed by occupational health professionals (N=3), e-health (online) interventions (N=3) and peer support (N=1). These were implemented by one or more of the following occupational health professionals: OPs,24 25 27–30 32 occupational nurses,29 30 occupational physiotherapists,27 31 occupational psychologists,30 31 social workers from OHS27 and trainers in the field of occupational medicine.26 A full overview of the study characteristics can be found in online supplemental table 1.

Supplemental material

Role of occupational health professionals and effects of interventions

Universal preventive interventions

Three studies involved universal preventive interventions, since the interventions in these studies were offered to a broad group of workers without specific risks. One study found statistically significant positive effects of the intervention,31 one found positive effects for the high-compliance group,30 and one found no significant effects.29

In the non-randomised trial by Ojala et al, municipal employees participated in a cognitive behavioural intervention programme. The two weekly sessions were facilitated by a multi-professional team, including an occupational physiotherapist, occupational psychologist and a nurse. Participants in the intervention group were found to have significantly lower scores on burnout and exhaustion than those in the control group at 9 months after baseline.31 Umanodan et al evaluated an on-site stress-management training (SMT) for employees from various sectors in a non-RCT. The intervention consisted of six sessions and the team offering the interventions consisted of, among others, an OP and occupational nurses. The authors did not report a significant effect on psychological distress based on intention-to-treat analysis at 6-month follow-up (N=149). However, when including only the 44 participants who participated in all six sessions (per-protocol analysis), significant favourable effects were found for the intervention group with regard to psychological distress.30 However, at baseline, the intervention group had significantly lower scores on quantitative and qualitative demand, psychological distress and physical complaints, compared with the control group. The study by Kawaharada et al, did not find significant reductions in response to stress.29 In this non-randomised study, public organisation office workers participated in three SMT sessions led by an OP and occupational nurse at the workplace. No significant differences were found between the intervention and waiting list control group with regard to stress and burnout outcomes at 1-month follow-up.29

Selective preventive interventions

Three studies evaluated interventions offered to high-risk occupational groups, of which one study found significant effects,26 one found partial positive effects28 and one found no effects.32

In the RCT by Limm et al, lower and middle level managers were offered several stress management interventions addressing their needs and focusing on organisational sources of stress. Statistically significant differences between the intervention and control condition in favour of the intervention group were found for self-reported stress measures but not for biological stress measures (eg, cortisol).26 Gärtner et al evaluated the effects of online screening followed by voluntary preventive consultations with OPs among nurses and allied healthcare professionals. In this study, no effects were found on distress and fatigue outcomes at 3- and 6-month follow-up.28 However, participants in the intervention group showed significant improvements in work functioning (eg, lack of energy and motivation) compared with those in the control group.28 In their quasi-RCT, Steel et al included hospital employees who were eligible for periodic health screenings.32 Participants in the intervention group received an electronic health survey with selective follow-up, which means that 20% of the participants who mostly needed it, were invited for a consultation with the OP. Those in the control group received a yearly screening (care as usual). Burnout and stress outcomes were measured at 19-month follow-up, but no significant effects were found between the intervention and control group.32

Indicated preventive interventions

Three studies fall under indicated prevention, because the interventions focused specifically on individuals who are already showing symptoms. Two studies found significant (short-term) results in favour of the intervention group25 27 and one study did not find effects.24

The study by de Boer et al evaluated an occupational health programme including consultations with supervisors and/or managers, and design of an individual action plan.25 In this RCT, significant effects in favour of the intervention group were found for emotional exhaustion and emotional distance at 6 months after finishing the intervention. However, these effects disappeared over time: 2 years after baseline no significant differences were observed between the intervention and control condition.25 Moreover, these results should be interpreted with caution, because the intervention group had statistically significant worse emotional well-being and social isolation at baseline compared with the control group. The study by Peterson et al evaluated a peer support group intervention for workers with high levels of exhaustion.27 The intervention consisted of 10 working group meetings led by physicians, social workers and physiotherapists recruited from the OHS. In this RCT, less exhaustion in the intervention group compared with the control group was observed at 1-year follow-up.27 In the RCT study by Notenbomer et al, in which an e-health intervention and OP care were offered to employees with frequent sickness absence, no significant effects were found for burnout.24 Additional data about the effects of the interventions in the included studies can be found in table 2.

Table 2

Intervention effects of included studies

Risk of bias

Figure 2 displays the results of the risk of bias assessment of the RCTs. All of the included RCTs were assessed with a high risk of bias in one or more of the domains, resulting in an overall high risk of bias. This is mainly due to the fact that blinding of participants in occupational health interventions is not possible and that outcomes are self-reported.

Figure 2

Risk of bias of randomised studies based on the Cochrane risk of bias tool for randomised trials (RoB-2) tool, depicted using traffic light plots and weighted bar plots according to the Risk-of-bias VISualization (Robvis) tool.

Figure 3 shows an overview of the risk of bias of the four non-randomised studies, with all studies scoring a serious risk of bias. With regard to potential confounding, only one study was assessed with a moderate risk of bias. The other three studies were scored with a serious risk of bias, due to participants being allocated to groups based on preference29 30 or based on selection by the occupational health service professionals.31 For missing data, one study was assessed as having a moderate risk of bias due to high proportions of missing data (>30%).32

Figure 3

Risk of bias of non-randomised studies based on the Risk of Bias in non-randomised Studies-of Interventions tool, depicted using traffic light plots and weighted bar plots according to the Risk-of-bias VISualization (Robvis) tool.

Discussion

This systematic review aimed to summarise the effectiveness of interventions delivered by occupational health professionals in preventing work-related stress complaints. Among the nine included studies, four studies did not report any significant effects, whereas the remaining five studies found either mixed effects, short-term positive effects or positive effects in a subgroup of participants demonstrating high adherence/compliance.

These findings can be explained by several underlying reasons. First of all, the majority of the interventions examined in the included studies were of short duration or low intensity. Three studies focused on a one-time intervention, but none of these yielded statistically significant positive effects.24 28 32 On the other hand, six studies investigated interventions consisting of multiple sessions or components, with four studies reporting statistically significant positive effects.25–27 31 This suggests that interventions with a higher intensity or frequency tend to yield more favourable results. This is in line with findings in a previous systematic review on burnout interventions for employees, in which the results suggested that a longer duration of interventions leads to more positive results.33

Second, our analysis revealed a substantial diversity in the outcome measures used across the included studies, both in terms of outcomes as units of measurement, as questionnaires used. This diversity underscores the complex and multifaceted nature of work stress. It is therefore recommended to develop a core outcome set for work-related stress measures and burnout. Such a unified set of outcomes would promote consistency and comparability across different studies, allowing for more comprehensive comparisons of studies and interventions.

Third, the included studies mainly evaluated individual focused interventions and not organisational focused interventions. This could be partially due to only including interventions with the involvement of occupational health professionals, who usually focus more on individual health, and that in general, controlled interventions at the organisational level targeting stress and burnout are scarce in literature.33 However, previous studies have shown that organisational stress interventions were more effective than individual interventions,34 and that combined interventions are more likely to result in longer lasting results than organisational interventions alone.35–37 Individual-focused interventions may not target systemic and interpersonal causes of stress sufficiently, focusing primarily on the individual’s ability to cope with stress rather than addressing the causes. Hence, without addressing the underlying organisational or environmental stressors (ie, high job demands), individuals may continue to experience high levels of stress despite their improved efforts to manage it. It is important to note that occupational health professionals possess expertise in both domains, making them ideally suited to play a more prominent role in prevention. By bridging the gap between individual challenges and needs, and organisational factors, occupational professionals should contribute to both a healthier workplace culture and workers’ (mental) well-being. It is therefore recommended to involve them more in organisational interventions.

Finally, the effectiveness of occupational health interventions can be affected by the sometimes poor implementation of these interventions. Factors contributing to poor implementation include participants not entirely following the intended programme or OPs being reluctant to initiate interventions.24 28 30 However, the majority of studies did not report about the actual implementation of the intervention in the workplace and/or compliance of the participants. To be able to understand if the (lack of) effectiveness is due to the intervention itself or due to (poor) compliance, it is recommended that future studies are more consequent in reporting about the adherence to the intervention. Moreover, in the majority of studies excluded from this review, interventions were not implemented by occupational health professionals, but, for example, the researchers themselves or specially trained coaches. Incorporating the professionals themselves into the implementation process is however important for ensuring the implementation of interventions in the long-term.

Quality of studies included

All of the studies included in this systematic review were assessed as having a high risk of bias. While this can affect the validity and reliability of the study findings, the risk of bias assessment needs to be considered in a nuanced manner. Both the RoB and ROBINS tool were used to assess the risk of bias in included studies to determine the quality and reliability of the evidence. However, the scores in both tools cannot be directly compared with each other. A positive judgement (low risk of bias) on the ROBINS tool should be interpreted as the study being comparable to a well-performed randomised trial with regards to that domain.22 Furthermore, the high risk of bias in the studies was mainly due to the lack of blinding, because both participants and health professionals know which group participants are assigned to. This is a well-known challenge in studies evaluating occupational health interventions.38–40 In addition, the availability of high-quality studies with low risk of bias is often limited in the field of occupational health research, because occupational health interventions are conducted in a complex and often uncontrollable context.38 39 All these sources of bias are challenging to mitigate completely due to practical constraints and ethical considerations. For these reasons, several alternative research methods have been discussed in literature, including experimental and observational designs.39 41 Nevertheless, in this study, we have only included controlled trials because they still represent the gold standard when evaluating preventive interventions.

Limitations and strengths

The findings reported in this systematic review need to be considered in light of some limitations. The heterogeneity of the included studies in terms of intervention types, study designs, target groups, outcome measures and baseline values limits direct comparisons and generalisability of the findings and made it impossible to perform a meta-analysis. It must be noted, however, that the results show mixed effects across all studies, regardless of possible variation in baseline differences. To overcome this problem of heterogeneity, we have included all types of interventions as long as they were delivered or applied by a professional defined as ‘occupational health’ or related to ‘occupational medicine’. However, a large proportion of studies was excluded due to unclarity about who delivered the intervention. It cannot be ruled out that studies mistakenly have been excluded, while in fact an occupational health professional was involved.

The main strength of this review is that, to the best of our knowledge, no previous reviews have focused specifically on the execution of the intervention and the involvement of occupational health professionals in prevention of stress and burnout. Another strength of this study is the systematic and thoroughly performed search. The search in online databases was followed by extensive hand-searching and snowball sampling of the included studies. However, despite this, it cannot be guaranteed that no studies were missed.

Conclusions

The aim of this review was to summarise the evidence concerning the effectiveness of interventions for the prevention of stress complaints and delivered by occupational health professionals. Five out of the nine included studies yielded positive outcomes on the short-term, while the other four did not report significant positive effects. All of the studies were scored with a high risk of bias. The results suggest that intensity of the intervention might influence the effectiveness. However, the overall body of evidence regarding the effectiveness of preventive interventions delivered by occupational health professionals, particularly in the context of addressing work-related stress, remains limited. The mixed findings in the limited number of studies emphasise a need for further high-quality research and a more nuanced understanding of the complex dynamics surrounding such interventions and their implementation.

Ethics statements

Patient consent for publication

Ethics approval

Not applicable.

Acknowledgments

The data that support the findings of this study are openly available in online libraries PubMed, Embase, PsycInfo and Medline. This systematic review is reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

References

Supplementary materials

  • Supplementary Data

    This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.

Footnotes

  • Contributors SOP, SvO, FS and KIP were involved in the design of the study. SOP and HL performed the search, screening and selection of studies. SOP and SvO performed the risk of bias assessment. All authors have contributed significantly to the final manuscript and gave their approval.

  • Funding This study is funded by the Dutch Ministry of Social Affairs and Employment.

  • Disclaimer The funder has no role in the study in terms of the design, data collection, analysis and interpretation, nor in the design of this manuscript.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.