# Fig. 1. Interventions covered in the guidelines on mental health at work
Target audiences of these guidelines are primarily individuals or entities responsible for the planning, programming or implementation of measures for the health, safety and well-being of workers. These can include occupational health & safety and mental health providers as well as service-delivery managers, employers and workers and their unions, organizations or cooperatives, human resource services, professional bodies, and employee education, well-being or training services. The guidelines and its derivative products will also have implications for international and national policymakers, planners, programme managers and researchers in mental health, occupational health and labour. The guidelines were developed in accordance with the WHO handbook for guideline development (26) and meet international standards for evidence-based guidelines. The steps for the development of WHO guidelines include the following, with further detail provided in the relevant annexes.

# Mental health promotion

# Prevention of mental health conditions

# Guideline contributors
Identifying who will be the contributors to the guideline process (Annex 1), and how conflicts of interest will be managed (Annex 2)

# Scoping the guideline
Deciding what the guideline should be about and what it will not address; the key questions that should be asked; and what the outcomes of interest are (Annex 3)

# Certainty of evidence
Deciding how confident we are about the certainty of that evidence in answering our key questions (Annex 4)

# Formulating recommendations
Developing the recommendation statements based on the above work (Annex 5)
Drafting this guideline document, and obtaining more inputs through wide peer review (Annex 6)

# Quality check
Review for approval to publish by WHO's quality assurance body (GRC)
Publishing the guideline, and actively supporting its dissemination

# Evidence reviews
Searching for the best available evidence to answer the key questions  (Annex 4)
How the guidelines were
developed  W H O / B l i n k M e d i a -N e i l N u i a
This section includes the recommendations and key remarks, a summary of the main highlights of the evidence, the rationale for the recommendations and the evidence-to-decision considerations. For full evidence profiles and supplementary evidence, see the web Annex. To interpret the certainty of the evidence (i.e. the differences between very low, low, moderate and high certainty of evidence), see Annex 4. To interpret the strength of the recommendation (i.e. the meaning of conditional and strong recommendations), see Annex 5.
Overarching remarks across all recommendations

# Organizational interventions for health, humanitarian and emergency workers
Organizational interventions that address psychosocial risk factors, for example reductions to workload and schedule changes or improvement in communication and teamwork, may be considered for health, humanitarian and emergency workers to reduce emotional distress and improve workrelated outcomes.

# Conditional recommendation, very low-certainty of evidence
Evidence and rationale No other direct evidence was available on the harms of implementing these universally delivered organizational interventions to at-risk groups.

# Evidence-to-decision considerations
Work-related risks in the health, humanitarian and emergency sectors place this group of workers at risk of mental health conditions. Organizational interventions to address such risks are considered a priority (62,63).  Providing reasonable accommodations promotes an inclusive work environment for workers with mental health conditions by enhancing equitable access to opportunities and resources at work.

# Organizational interventions for workers with mental health conditions
Reasonable work accommodations should be implemented for workers with mental health conditions, including psychosocial disabilities, in line with international human rights principles.

# Strong recommendation, very low-certainty of evidence
Implementation remarks:  In line with UNCRPD Article 27 on Work and Employment, workers with mental health conditions should not be discriminated against. However, there are concerns that accessing or benefitting from such support will identify a worker as having a mental health condition or as being perceived as unable to cope with work, which may subject that worker to discrimination unless measures are taken proactively within an organization to mitigate mental health stigma and protect the privacy of the person.
 Organizational mitigation of stigma for mental health conditions may contribute to reducing concerns about confidentiality and stigma and can facilitate ease of access to accommodations by promoting voluntary disclosure. Accommodations can be implemented without identifying workers to wider colleagues or in accordance with the worker's preference.
 There is insufficient evidence to identify whether one category of interventions is superior to another. Workers living with mental health conditions should be accommodated to work in a person-centred manner, according to their needs, requirements and preferences. Direct supervisors play a critical role in supporting workers.
 Reasonable accommodations may be applied for any worker with a mental health condition(s) including those returning from absence associated with a mental health condition. However, they may also be utilized for workers living with mental health conditions, who have not been on absence, and who remain in work or who newly join work.
 Respect for the human rights of people living with mental health conditions or psychosocial disabilities is a necessary precondition for this recommendation; otherwise, the implementation of reasonable accommodations may risk lacking a rehabilitative approach.

# Evidence-to-decision considerations
Workers with mental health conditions and psychosocial disabilities experience significant barriers to sustaining their participation in work despite their interest, willingness, and capacity to participate in work. Work accommodations seek to ensure that the outcomes that stakeholders value are improved: sustaining time on the job (i.e. tenure) and improved mental health. However, stigma and fear of repercussions remain critical barriers to workers' confidence in feeling safe to disclose their mental health status, and consequently to access accommodations (71).
Resource requirements vary by the type of accommodation provided. In a dated national survey conducted in the USA, over half of workplaces reported no initial direct costs or maintenance costs of the accommodations they applied.
One third reported initial and maintenance costs of less than US$ 100, with a minority reporting these costs larger than US$ 500 (72). No specific study on cost-benefit or costeffectiveness analysis was identified.

# Manager training for mental health
Training managers to support their workers' mental health should be delivered to improve managers' knowledge, attitudes and behaviours for mental health and to improve workers' help-seeking behaviours.

# Strong recommendation, moderate-certainty of evidence
Evidence and rationale

# M E N D A T I O N
9A Universally delivered psychosocial interventions that aim to build workers' skills in stress management -such as interventions based on mindfulness or cognitive behavioural approaches -may be considered for health, humanitarian and emergency workers to promote positive mental health and reduce emotional distress.

# For mindfulness and other contemplative interventions,
there was moderate-certainty evidence indicating moderate effects on reducing mental health outcomes (depression, stress) and small effects on general distress and burnout.
While there was a moderate effect on anxiety, this evidence was considered very low-certainty. There was low certainty in the moderate improvements in positive mental health (self-compassion).
For psychosocial interventions for indicated at-risk workers, there was moderate certainty of effects on high reductions in levels of burnout (exhaustion).
Overall, no outcomes were reported for substance use.

# Psychosocial interventions for indicated at-risk workers
did not demonstrate the desired effect on burnout depersonalization, whereas there was a moderate effect on burnout exhaustion. No other direct harms were identified.

# Evidence-to-decision considerations
The evidence-to-decision considerations were largely identical across all individual intervention recommendations (8, 9 and 10). The additional unique considerations for indicated individual interventions (workers with emotional distress) are outlined in Recommendation 10.
In these at-risk sectors there can be a particular stigmatization regarding disclosure of mental health due to concerns about its impact on career progression (121)

# Evidence-to-decision considerations
The evidence-to-decision considerations were largely identical across all individual intervention recommendations (8, 9 and 10). Additional considerations for indicated individual interventions are outlined here.
Consideration is given to the fact that entry into such programmes is by meeting criteria for emotional distress which may be stigmatizing if care is delivered in the work setting. Therefore, in terms of sociocultural acceptability, it is unclear whether such interventions are considered acceptable at work -despite well-designed RCTs for workers with emotional distress being conducted in workplaces with no known reports of harms (such as perceptions or fears of stigma or discrimination).
No direct evidence was available on cost-effectiveness. For work-directed care plus clinical care, compared with care as usual for workers with depression, there was a low certainty in small (medium-term follow-up) to moderate (long-term follow-up) reductions in depressive symptoms.
There was a small effect in reducing the days on absence at medium-term (moderate-certainty) and long-term (low-certainty). However, there was moderate certainty of no difference in the likelihood of being absent, versus not being absent. There was very low to low certainty of evidence for small effects on improving work functioning (at medium term (not significant) and long term, respectively).
There was very low certainty that work-directed care plus clinical intervention was no more superior (i.e. equally

# Evidence-to-decision considerations
Mental health conditions are considered to be a leading cause of absence for workers (129,130).  Leisure-based physical activity was not recommended due to uncertainty for its singular effect on key outcomes since the control conditions included physical activity.

# Recommendations for gaining employment for people living with mental health conditions
Implementation remarks:  Multi-stakeholder coordination (person, family/community, workplace, representative) is required to mobilize resources and strategies which enhance vocational and economic inclusion.
Involvement of these stakeholders and selection of the intervention should be based on the prospective worker's preferences.
 It is important to include people with lived experience of mental health conditions in the design and delivery of these programmes in order to optimize person-centred approaches and to empower people in making decisions for their own well-being.
 When people start their employment, support can continue, in order to support maintaining employment.
 Such strategies should be contextualized to people's social and cultural environment, using formal and non-formal recovery-oriented interventions that may be available.   and supported employment may be resource-intensive approaches, which may not be feasible in low-income settings since there is a need for available vocational and mental health services to take an active role in delivering these programmes.

# Evidence-to-decision considerations
For health equity, equality and discrimination, it was noted that the majority of the evidence relates to severe mental health conditions. For example, in one review (135), the majority of included diagnoses were psychotic disorders and, in van Rijn (137) the majority were schizophrenia, followed by affective disorders and major depression. Fadyl As it is unclear whether the potential benefits of screening programmes outweigh potential harms, the GDG did not make a recommendation for or against screening programmes during employment.

# Key remarks:
 This statement does not apply to screening which may be required by necessity of regulation in some occupations, or screening when workers have been exposed to potential hazards to (mental) health.
Screening programmes 19 Evidence for pre-employment screening was not considered as it falls outside the scope of the guidelines.

# Evidence and rationale
Key question 13 investigated whether the use of screening programmes -i.e. programmes that are designed to identify workers with mental health problems and which are then followed by providing them with, or directing them towards, the necessary support during employment 19 -were beneficial (Annex 3). A systematic review of primary studies was conducted. Thirteen studies were identified, with seven eligible for GRADE, for screening programmes versus screening followed by care as usual, wait list control or no intervention (web Annex).
Low-certainty data indicated no impact of screening programmes on reducing mental health symptoms or improving positive mental health. Very low-certainty data found small not significant improvements in work functioning, positive effects on productivity at 5 months which were not sustained at 12-month follow-up, and no effects on job satisfaction. There was a negligible improvement in absence which was not significant, although there was evidence for a small positive effect, albeit of very low certainty, at longer-term 5-year follow-up. One trial indicated greater likelihood of absence and lower likelihood of improvement in productivity for workers in receipt of screening programmes. Small improvements from lowcertainty data suggested that screening programmes were beneficial with regard to immediate help-seeking behaviours but this was not sustained at follow-up assessments.
Adherence to the supports following positive screening was low in one trial. No other direct harms were reported.
The GDG concluded that there is a lack of clear evidence that the desirable effects of screening programmes during employment outweigh the undesirable effects (negligible or mixed change in key outcomes such as mental health symptoms and absence). Additional concerns were raisedincluding confidentiality and the risk of the likelihoods of false positives and false negatives when screening for mental health symptoms -such that one-time-screening results, if inaccurate and if misinterpreted, could lead to harms.
Reporting bias is also a concern in screening programmes where workers are likely to under-report their symptoms for fear of confidentiality breaches (139). On balance, the GDG concluded that it was not possible to provide a recommendation for or against screening programmes; therefore no recommendation was made.
The GDG highlighted that the "no recommendation" decision pertains to screening programmes conducted during employment, rather than pre-employment screening.
The GDG noted that if screening takes place at work (e.g. by necessity of regulations), then the screening programmes should at least include:

# Evidence-to-decision considerations
Improvement of mental health and work-related outcomes is valued by all stakeholders. While two included studies indicated that user satisfaction was positive, additional data indicate that workers are concerned about stigma and discrimination if they screen positive, as well as the confidentiality of their data to employers. Indeed, the lowest preference was given to screening programmes (web Annex:
Values and preferences survey). This is also reflected in wider literature where such concerns generate under-reporting of mental ill-health by workers, even if their symptoms would indicate a need for further support (139).
Resource requirements for screening alone may be small and limited to the mode of delivery (digital, paper) and to the automation or not of the interpretation of results. Whereas follow-up when screening positively will vary substantially in resources pending options available (from self-help to physician appointment). A cost-effectiveness analysis in one included study from the Netherlands identified net benefits of  651 per staff member, or for every euro invested a return of between  5 and  11 for employers.

# Research gaps
The GDG identified several gaps in the evidence included within the scope of these guidelines.

# Overall research gaps 
Across all intervention types, there is a critical need, where applicable, to increase the volume and quality of evidence for effectiveness and feasibility in under-researched populations -i.e. the informal sector, SMEs and LMICs -and for the selective at-risk workforce, such as international and national humanitarian workers, health workers not responsible for direct clinical care (e.g. workers in health administration), community health workers and other occupations at risk of negative mental health outcomes.
Across all intervention types, there is a need for sociodemographic subgroup analyses to determine whether there are differential benefits or harms associated with intervention recipients' sociodemographic (e.g. gender, age, race) or occupational status (e.g. occupational sector, contract status (formal, informal, self-employed, size of workplace). This includes clear reporting of these characteristics under study or review, and clear reporting of the mental health status of participants at baseline.
Overall, there is a need for implementation research to study the acceptability, accessibility and uptake of interventions in order to better inform implementation guidance.
Overall, there is a need for quality investigation to study the effectiveness and feasibility of delivering preventive interventions which are combined at multiple levels of delivery (e.g. combinations of organizational, managers, workers and individual interventions).
There is a need to increase the availability of high-quality research on organizational interventions (including policies), and their impact on mental health and work-related outcomes, regarding salient risk and protective factors at work (which were not encountered by the evidence reviews of these guidelines) such as bullying, parental leave etc.
There is also a need to increase high-quality research in the cost-effectiveness of interventions for mental health at work.

# Research gaps for organizational interventions

# Across organizational interventions
The guidelines are available on the WHO website in English, with the executive summary available in all six United Nations languages. National ministries responsible for mental health and occupational health will be notified of the guidelines through WHO's regional and country offices. Ministries for labour and employment, and representative bodies for workers and employers, will be notified of the guidelines through the ILO. The guidelines will be shared with a broad network of international partners, including representative organizations for persons responsible for or committed to the health, safety and well-being of workers, as well as WHO collaborating centres, universities, nongovernmental organizations and UN agencies.
To facilitate implementation of the recommendations, a policy brief will accompany the guidelines, developed jointly by WHO and ILO. The policy brief will be made available in the six United Nations languages to facilitate wide dissemination and will present policy and implementation options which will be derived from the guidelines. WHO regional and country offices will encourage implementation at country level. The implementation may also be supported locally through the adoption and implementation of the WHO Comprehensive Mental Health Action Plan (2013-2030) and the WHO global strategy for health, environment and climate change, both of which have been adopted by the World Health Assembly.
Additionally, WHO will disseminate the guidelines and the joint policy brief through a broad network of international partners, including national ministries of health, WHO collaborating centres, key stakeholder groups (which represent the target audience of these guidelines), universities, nongovernmental organizations and United Nations agencies. The ILO will promote the dissemination of the policy brief among its tripartite constituents, including ministries of labour, in addition to employer and worker organizations. This will provide policy guidance on the roles and responsibilities of actors in the world of work in preventing, protecting and promoting, and supporting mental health at work. 20 See:  (accessed 29 May 2022).
Dissemination and update of the guidelines Monitoring and evaluation of the uptake and implementation of the guidelines WHO will seek to monitor uptake and implementation of the guidelines in national policies and programmes by reviewing the number of countries that have adapted or endorsed the guidelines. WHO will use the WHO atlas  and other routine approaches (e.g. the WHO MiNDbank database 20 to assess how national policies and service delivery for workers have been adapted to integrate the recommendations. WHO will seek to continue to collect regular feedback from implementation activities and key stakeholders in order to evaluate the usefulness and impact of the guidelines.

# Future updating of the guidelines
The guidelines are expected to be valid for a period of five years. The WHO Secretariat, in consultation with technical experts, will continue to follow research development in mental health promotion, prevention and interventions for workers -particularly for questions in which the certainty of evidence was found to be of low or very low certainty. If new evidence emerges or other important considerations arise which may have an impact on the current recommendations, WHO will coordinate an update of the guidelines, following the procedures outlined in the WHO handbook for guideline development, second edition.

# Informal sector
All workers in unincorporated enterprises that produce at least partly for the market and are not registered.
For the purposes of these guidelines, a manager is a worker who is responsible for supervising, managing or leading another worker or workers -i.e. managers are employees who plan, direct, coordinate and evaluate the overall activities of enterprises or of organizational units within them. 23

# Adverse effects
For the purposes of these guidelines, adverse effects are defined as outcomes of the key questions and could include any untoward occurrence to a study participant caused by the intervention of interest, such as drop-out.
Burnout is a syndrome conceptualized as resulting from chronic workplace stress that has not been successfully managed. It has three dimensions: feelings of energy depletion or exhaustion; increased mental distance from one's job, or feelings of negativism or cynicism related to one's job; and reduced professional efficacy. 21 Burnout may be a frequently used idiom for distress in the workplace.

# Emotional distress
This constitutes, for instance, sadness, anger, anxiety, irritability, or other negative emotional states. People in emotional distress may or may not meet ICD criteria for a mental disorder.

# Evidence-todecision frameworks
These are tabular displays of relevant considerations which are used to make a decision or to formulate a recommendation.

# Formal sector
All workers in incorporated enterprises.
The Grading of Recommendations, Assessment, Development and Evaluation is a system for assessing the certainty of a body of evidence and for structuring considerations when formulating recommendations on clinical or public health guidelines.

# GRADE evidence profiles
These are tabular displays of summary measures of effect and the GRADE certainty assessments of the body of evidence for a specific question -usually defined by population, intervention, comparator and outcome (PICO) format.

# Help-seeking behaviour
For the purposes of these guidelines, help-seeking behaviour is defined as an outcome of the key questions, which includes a person taking actions to seek or access support for a given problem such as a mental health condition.

# Informal employment
This includes employees (or persons not classified by status in employment) who are not protected by national labour legislation in that job (i.e. not affiliated to a social security scheme related to the job or not entitled to certain employment benefits); employers, members of producers' cooperatives and own account workers (only if what is produced is for sale) in a unit of production that is considered informal; and contributing family workers. 22

# Managerial, leadership style and communication
For the purposes of these guidelines, managerial, leadership style and communication are outcomes of the key questions which capture the manner of communication, consideration of individual employees, justice in managerial behaviours, social support, provision of clarity, supply of information and feedback, promotion of employee participation and control, or leadership style (e.g. abusive, laissez-faire, authoritarian, participative).

# Mental disorder
As defined by the ICD-11, mental disorders are syndromes characterized by clinically significant disturbance in an individual's cognition, emotional regulation, or behaviour that reflects a dysfunction in the psychological, biological or developmental processes that underlie mental and behavioural functioning. These disturbances are usually associated with distress or impairment in personal, family, social, educational, occupational or other important areas of functioning.

# Mental health
A state of mental well-being that enables people to cope with the stresses of life, to realize their abilities, to learn well and work well, and to contribute to their communities. Mental health is an integral component of health and well-being and is more than the absence of mental disorder.

# Mental health conditions
A broad term covering mental disorders and psychosocial disabilities. It also covers other mental states associated with significant distress, impairment in functioning or risk of selfharm. It thus includes significant emotional distress.

# Mental health knowledge and attitudes, skills
For the purposes of these guidelines, mental health knowledge, attitudes and skills are outcomes of the key questions. This term captures the key target variables of interventions to reduce stigma through increasing literacy (knowledge) for mental health, changing stigmatizing attitudes, and actions or behaviours which indicate the provision of appropriate support to others

# Positive mental health
For the purposes of these guidelines, positive mental health is an outcome of the key questions.
It is intended to capture aspects of mental well-being, life satisfaction, positive self-concept, self-esteem, self-control, self-efficacy resilience (in contrast to mental health conditions).

# Psychosocial disability
Aligned with the Convention on the Rights of Persons with Disabilities, it is disability that arises when someone with a long-term mental impairment interacts with various barriers that may hinder the person's full and effective participation in society on an equal basis with others. Examples of such barriers are discrimination, stigma and exclusion. 24 England MJ, Butler AS, Gonzalez ML, editors. Psychosocial interventions for mental and substance use disorders: a framework for establishing evidence-based standards. Washington (DC): National Academies Press; 2015. 25

# Psychosocial interventions

# Quality of life
For the purposes of these guidelines, quality of life is an outcome of the key questions which captures an individual's perception of their position in life in the context of the culture and value systems in which they live and in relation to their goals, expectations, standards and concerns.
For the purposes of these guidelines, functioning is an outcome of the key questions which describes the ability to conduct activities and to participate in life domains other than work (e.g. cognition, communication, mobility, self-care, relationships, domestic life, community and civic life activities, life participation).

# Satisfaction with care
For the purposes of these guidelines, satisfaction with care is an outcome of the key questions and captures users' and families' satisfaction with care, such as their involvement in the decision-making process, quality of information provided, communication about the condition, and care providers' skills and competencies.

# Substance use
For the purposes of these guidelines, substance use is an outcome of the key questions, capturing alcohol or illicit drug use measured as alcohol use, frequency of alcohol use, alcoholrelated problems, alcohol initiation, drunkenness initiation, binge drinking and alcohol misuse.
Drug use refers to the use of cannabis, opioids and/or stimulants/misuse of prescription drugs.

# Suicidal behaviours
For the purposes of these guidelines, suicidal behaviours are an outcome of the key questions, capturing self-harm (including suicide attempt), suicidal ideation and suicide mortality.
For the purposes of these guidelines, a worker is any person above 18 years of age in paid work.
Workers (persons in employment) are usually defined as all those of working age who, during a short reference period, were engaged in any activity to produce goods or provide services for pay or profit.

# Work-related outcomes
For the purposes of these guidelines, work-related outcomes are an outcome of the key questions, capturing a broad range of variables which are indicative of a person's functioning at work, such as absenteeism (regular absence from work), presenteeism (being at, or present at, or attending work when not fully functioning and thereby reduced efficiency is assumed), productivity (effectiveness in work tasks), work engagement (perception of a fulfilling connection to work), work ability (functional capacity and competence to participate in work), absence, turnover, resignation, return to work, job retention, job satisfaction, job tenure or length, employment status (employed part-time, full-time, unemployed).

# Annex 1

# Contributors to the guidelines
The WHO Steering Group followed the current WHO Compliance, Risk Management and Ethics (CRE) policy. Prospective members of the GDG, ERG and evidence team were asked to complete the WHO Declaration of Interests (DOI) form and to provide their curriculum vitae. These documents, along with additional information (obtained through the Internet and bibliographic database searches), were reviewed by the WHO Secretariat to identify conflicts of interest related to the guideline topic.
Additionally, the names and brief biographies of potential GDG members were published on the WHO website for more than two weeks, together with a description of the objective of the meeting, for public review and comment. No concerns were received.
Interests were assessed as insignificant or minimal if they were considered unlikely to affect, or unlikely to reasonably be perceived to affect, the individual's judgement when assessing evidence or formulating recommendations. If an interest was deemed to be potentially significant, the following management options were considered: 1) limited participation of the individual in the guideline development process; and 2) full exclusion from the process.
At the beginning of the guideline meetings, the declaration of interests of each GDG member was presented. GDG members and evidence teams attending the meetings were asked to provide updates if their declarations of interests had changed.
Where changes had occurred, the WHO Steering Group considered the management options as noted above. The GDG, ERG, evidence teams and meeting observers were required to sign a confidentiality agreement.
ILO staff are subject to declarations of interest and conflict of interest management according to the policies of the ILO (Office Directive on Ethics in the Office (143) and, in the same way as WHO staff, are subject to the Standards of Conduct for the International Civil Service. WHO staff are also subject to WHO's Code of Ethics and Professional Conduct (144). Meeting observers and organization representatives were not required to complete a declaration of interests because they did not actively participate in the guideline development discussions.
All contributors declared no interests, with the exception of those listed below. A summary of declared interests and how they were managed is provided:

# Managing declarations of interest and conflicts of interest
Prior to the development of the guidelines, an initial meeting -the Landscape Forum on Workplace Mental Health was held in Geneva, Switzerland in November 2019. One key objective was to discuss the extent of evidence for interventions addressing mental health at work. Following this meeting, the WHO Steering Group performed preliminary scoping of the available evidence in preparation for a draft scope for the guidelines. With the support of the Steering Group and guideline methodologist, the scope was reviewed by the GDG at its first meeting, held virtually in April 2020, which discussed and agreed on the final scope and PICO (population, intervention, comparison, outcome) questions of the guidelines.
Background questions were additionally devised in order to scope the best available evidence sources and to provide relevant contextual information for the prospective main body of the guidelines and for prospective evidence-to-decision considerations -in particular, 1) risk factors at work and their impact on mental health outcomes; and 2) the prevalence of mental health outcomes in general working populations and specific subpopulations (such as those identified as minority groups and humanitarian and health workers).
Members of the WHO Steering Group, in consultation with the GDG and the methodologist, developed a list of outcomes that were most relevant to specific PICO questions. The GDG then rated each outcome on a scale from 1 to 9 and indicated whether it considered each outcome critical (rated 7-9), important (rated 4-6) or not important (rated 1-3) for decision-making.
The final key questions are provided in the following table which includes the critical and important outcomes. Definitions of terms can be found in the glossary. The details of the PICO format for each key question are provided in the relevant section of the web Annex: Evidence profiles.
Critical outcomes are: mental health symptoms and disorders; quality of life and functioning; work-related outcomes.
Important outcomes are: adverse effects; positive mental health; satisfaction with care.
QUESTION 13. Are screening programmes for mental health conditions at work acceptable and do they reduce symptoms of mental health conditions in workers?
Critical outcomes are: mental health symptoms and disorders; user satisfaction; work-related outcomes.
Important outcomes are: adverse effects; positive mental health; quality of life and functioning.

# Evidence and rationale

# Research priorities for manager training

# Common to all manager training for mental health
Research on manager training for mental health should include measurement of supervisees' work-related outcomes such as absenteeism, presenteeism, productivity and performance.
Increase evidence of the effectiveness of manager training for mental health on priority outcomes (e.g. workers'
suicidal behaviours and substance use, managers' leadership style).
Include a longer duration of follow-up (greater than 6 months) for key outcomes such as supervisees' mental health.
An increase in studies that identify effective components of manager training for mental health, including delivery components (e.g. duration) and content components.
An increase in better-quality studies and/or trials of leadership-oriented manager training and its impact on health outcomes.
An increase in better-quality studies on interventions that address help-seeking outcomes effectively (e.g. by mitigating stigma in the workplace).
For selective at-risk sectors  More studies to investigate the effectiveness and feasibility of manager training for mental health in health, emergency and humanitarian work settings.

# Research priorities for worker training
Common across workers' training  An increase in better-quality evidence for mental health literacy and awareness training and its effects on provision of help to colleagues in distress and on increasing help-seeking behaviours (including for the prevention of suicide).
An increase in studies which identify effective components of workers' training for mental health, including delivery components (e.g. duration) and content components.
For selective at-risk workers  An increase in higher-quality and sufficiently powered research to determine the effectiveness of training health, humanitarian and emergency personnel in knowledge, attitudes and skills for mental health.
An increase in evidence which identifies medium-to long-term follow-up duration effects to inform decisions as to how frequently training should be delivered.

# Research gaps for individual interventions

# Common across individual interventions
An increase in better-quality studies which ascertain the incidence of workers meeting the criteria for mental health diagnosis through use of diagnostic assessments at baseline and follow-up to determine the extent of prevention of mental ill-health.
An increase in better-quality studies which assess the comparative efficacy and cost-effectiveness of specific individual interventions, which include medium-to long-term follow-up to assess sustainability of effects.

# Annex 4
Reviewing the evidence and supporting evidence

# Evidence reviews for key questions
Details of the selection process, search strategies, included reviews and primary studies for each PICO question are presented in web Annex.
The Cochrane Database of Systematic Reviews, PubMed, EMBASE, PsycINFO and Global Index Medicus were searched to identify existing systematic reviews that answered the key questions. On the advice of GDG members, the methodologist and expert members of the evidence teams, where suitable reviews for specific outcomes were not available within the past 5 years, the time frame was extended to a maximum of 10 years. The reviews that were identified were then evaluated according to the following criteria:  whether they reported sufficient information to allow for an assessment of the certainty of the evidence (e.g. tables with characteristics of included studies, risk-of-bias assessments at the study level, results of meta analyses in forest plots);  the date of the most recent review to ensure that the most up-to-date evidence was used.
The evidence teams prioritized the most recent and highest-quality (based on AMSTAR II ratings) reviews for each question in relation to the population, intervention, comparison and outcomes. As many reviews as necessary were included to address each question. A search strategy was developed in collaboration with the methodologist and evidence teams to harmonize common search terms and strategy across the reviews. Reviews which included randomized designs were prioritized in all key questions; however, controlled observational designs were also considered because of existing knowledge on the common design of research in occupational settings/populations.
For two key questions (4 and 5) an update of an existing review was pursued in order to capture additional studies to better answer the specific PICO questions. Question 13 was not addressed in an existing systematic review, and a systematic review of primary studies was conducted. The evidence team, in consultation with the methodologist and the WHO Steering Group, devised a new search strategy to identify relevant primary studies (web Annex). A total of 36 systematic reviews and nine additional primary studies were included. The systematic review team also identified one network meta-analysis.

# Supporting evidence to supplement evidence-to-decision considerations
In light of global changes in the modes of working as a result of the COVID-19 pandemic, the WHO Steering Group and GDG considered areas of importance to supplement the evidence reviews, namely: the values and preferences of key stakeholders and the implementation barriers and facilitators. Additionally, in light of the dearth of literature reported by the evidence teams in relation to the informal sector, a third piece of supplementary evidence was commissioned. Full reports of all three can be found in web Annex.
A mixed-methods survey was commissioned to capture current values and preferences of key stakeholders -workers, employers, providers of mental health/occupational health services, including union representatives -in relation to the outcomes and interventions in the guidelines scope. Key data from the survey were included in the evidence-to-decision considerations.
A semi-structured interview with experts and providers of care for the informal sector was conducted in order to identify the needs and potential avenues of work and mental health service delivery for this population.
A review of qualitative research was commissioned on the barriers to, and facilitators of, implementing interventions that support workplace mental health. GRADE CerQual (Confidence in the Evidence from Reviews of Qualitative research) 27 was used to assess confidence in the findings of qualitative evidence.

# Certainty of evidence
After identifying the best available evidence to answer each key question, another step was taken to determine the certainty of this evidence -in other words, how confident could the GDG be that the evidence (estimate of effect) supported the making of any recommendations on the basis of that evidence. The GRADE system was used to assess the certainty of the body of quantitative evidence (from the evidence reviews) for each critical and important outcome (146). 27 See: /, accessed 29 May 2022.
Guidelines on mental health at work
The evidence teams, supported by the methodologist, developed evidence profiles to summarize relative and absolute estimates of effects and an assessment of the certainty of the evidence. The certainty of evidence for each question and each outcome was rated as "high", "moderate", "low" or "very low" on the basis of established criteria, namely:
 study design (e.g. randomized designs increase certainty, observational designs reduce certainty);  risk of bias (e.g. problems with how the studies were designed or conducted reduce certainty);  inconsistency (e.g. if the studies in the review are very different in their results, this reduces certainty);  indirectness (e.g. if the studies are not specific to the key PICO question (for instance, the population is slightly different) this reduces certainty);  imprecision (if there is a smaller number of participants in the studies, or the confidence intervals  are wide, this reduces certainty); and  publication bias (e.g. if there are factors that would have unfairly enhanced the likelihood of these studies being published, this reduces certainty) (147).
These assessments were presented to the GDG in GRADE evidence profiles for discussion and formulation of recommendations. Evidence profiles for each key question are shown in web Annex.

# Certainty Interpretation
We are very confident that the true effect lies close to the estimate. Further research is unlikely to change confidence in the estimate of effect.
We are moderately confident in the estimate of effect. The true effect is likely to be close to the estimate of effect, but there is a possibility that it is substantially different.
Further research is likely to have an important impact on confidence in the estimate of effect and may change the estimate.
Our confidence in the estimate of effect is limited. The true effect may be substantially different from the estimate of effect. Further research is very likely to have an important impact on confidence in the estimate of effect and is very likely to change the estimate.

# Very low
We have very little confidence in the estimate of effect.

# Developing the recommendations
The GDG met virtually for six duplicate sessions in June 2021. Graham Thornicroft and Jose Luis Ayuso-Mateos were chairs of the meetings, which were held in duplicate sessions to accommodate the differences in time zones of GDG members.
Corrado Barbui, the methodologist, was selected as vice-chair due to anticipated absences of the two chairs.
Evidence reviews, supplementary evidence and GRADE tables were shared in advance with GDG members and were presented throughout the meetings. Formulation of the recommendations and their strength ratings were facilitated by the chairs and supported by the methodologist.
The GDG benefited from a structured evidence-to-decision (EtD) framework which was developed by the evidence teams, with support from the WHO Steering Group and the methodologist, to guide the development of recommendations. The information which contributed to the EtD framework was informed by the systematic reviews, supplementary evidence, and the expertise of the GDG.
The EtD factors were: the priority of the problem, certainty of the evidence, balance of desirable and undesirable effects, values, resources required, certainty in the resources required, cost-effectiveness, feasibility, health, equity, equality and non-discrimination, human rights and sociocultural acceptability. The latter two factors were adapted from the WHO INTEGRATE EtD (148), replacing the items of equity and acceptability in the GRADE DECIDE EtD (149).
Each recommendation could be for or against a specific intervention, and either strong or conditional (150).
 A strong recommendation means the GDG was confident that the desirable effects of adherence to a recommendation outweighed the undesirable effects.
 A conditional recommendation means that the GDG concluded that the desirable effects of adherence to a recommendation probably outweighed the undesirable effects.
WHO's guideline recommendations are developed through a process that aims to achieve consensus among the GDG members.
Consensus was defined as a two-thirds majority vote. The GDG thus discussed and agreed on the recommendations, including the wording and direction (for or against the intervention) by consensus. The strength of each recommendation (strong or conditional) was agreed on by voting. Because meetings were held each day in duplicate, the progress of the first group of GDG members on a given discussion was then presented to the second group for further discussion and refinement. If the second group had major substantive disagreements with the recommendation, its revision was then presented to the first group in a final meeting.
Had there been major disagreement by the end of the final scheduled meeting, there was an agreement to reconvene the GDG if needed. This was not the case.

# Annex 6

# Drafting the guidelines and external review
Following the formulation of the recommendations by the GDG, the Responsible Technical Officer drafted the guidelines for review by the GDG and ERG. The role of the peer review was not to change the recommendations agreed by the GDG; however, if the peer reviewers had identified major concerns, these would have been brought back to the GDG for consideration. This situation did not occur.
The WHO Steering Group reviewed all peer review comments and, following discussion, revised the guidelines for clarity while making sure that the recommendations remained consistent with the original meaning as formulated by the GDG.
WHO has an internal approval and quality assurance process to ensure that all WHO publications, including guidelines, meet the highest international standards for quality, reporting and presentation. These guidelines were reviewed and approved by the WHO Guidelines Review Committee (GRC). Finally, the guidelines were prepared for publication and dissemination.