Interventions to improve occupational health in depressed people
Abstract
This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:
This review will evaluate the effectiveness of interventions aimed at reducing work disability in employees with depressive disorders. The effectiveness of two types of interventions will be considered:
(1) Interventions directed at the workplace (e.g. modified work)
(2) Interventions directed at the individual worker (e.g. treatment of depressive disorder or occupational therapy).
Background
Depression is a major public health problem, affecting about 121 million people worldwide. The lifetime prevalence of depression is estimated at 15% to 16% (Bijl 1998;Kessler 2003), while the prevalence rate of depression is estimated to be 9% to 10% (Greenberg 2003; Kessler 1994). The symptoms of a depressive disorder include the presence of one or two core symptoms of low mood and/or loss of interest, coupled with other symptoms such as feelings of inadequacy and hopelessness, sleep disturbance, weight change, fatigue, impaired concentration, agitation or slowing down of movement and thought and suicidal ideation (APA 1994). Depressive disorders can be classified along a continuum by levels of symptom severity, number of mental or physical symptoms and duration. Corresponding diagnostic categories range from mild fluctuating depression (dysthymia) and sub clinical states (minor depressive disorder) to major depressive disorder (APA 1994).
Besides the serious consequences in terms of individual suffering, depression also has a large impact on social functioning, social relationships and work functioning of patients (Hirschfeld 2000). The high prevalence of depression, combined with its impact on work functioning, results in extensive societal consequences. As a result, depression is the leading cause of disability as measured by years lived with disability (YLDs) (WHO 2001). In 2000, depressive disorders were the fourth leading contributor to the global burden of disease in terms of Disability Adjusted Life Years (DALYs), which is the sum of years of productive life lost due to premature mortality and the years of productive life lost due to disability (Ustun 2004). By the year 2020, depression is projected to reach second place in the ranking of DALYs, calculated for all ages (Murray 1997). Today, depression is already the second cause of DALYs in the age category of 15 to 44 years. The annual costs of depression are estimated to be about $83 billion in the United States (Greenberg 2003) and a substantial part (75% to 80%) is related to indirect costs due to loss of productivity at work, sickness absence and work disability (Goetzel 2002; Goetzel 2003; Stewart 2003).
From an individual point of view, prevention of work disability is essential because employment is an important component of quality of life. A study in the UK revealed that being able to work was viewed as the sixth most important aspect of quality of life by healthy persons. For persons suffering from an illness, being able to work was even judged to be the third most important aspect of quality of life (Bowling 1995). Moreover, depression is more highly prevalent in unemployed or work disabled persons compared to employed individuals.
Depression can be reliably diagnosed and effectively treated. Current practice guidelines for the treatment of major depressive disorder recommend pharmacotherapy, psychotherapy or a combination of both. Pharmacologic treatment for major depressive disorder includes tricyclic antidepressants, selective serotonin reuptake inhibitors (SSRI), monoamine oxidase inhibitors (MAO‐inhibitors) and selective norepinephrine reuptake inhibitors (Hansen 2005). With regard to psychotherapy, a wide range of psychotherapeutic models are now being used including cognitive behavioural therapy (CBT) and interpersonal therapy (Churchill 2001). These interventions are all directed at the individual worker and target the depressive symptoms. However, effective treatment of depressive symptoms does not always have an immediate effect on work functioning. In general, work functioning often lags after symptom reduction (Simon 2001; Mintz 1992; Hirschfeld 2000).
Prevention of work disability associated with disease falls within the scope of occupational health. Interventions aimed at improving occupational health can be classified into three strategies: (i) elimination or control of health hazards at work, (ii) changing health‐related and disability‐related behaviour and skills among workers, and (iii) prevention or better treatment of disease and related disabilities (Verbeek 2004). The second and third strategy are both directed at the individual worker. In addition, interventions can be either carried out at the workplace or in general health‐care settings. According to this view, any intervention that prevents work disability of depressive workers is an occupational health intervention.
Applied to workers who already have a depressive disorder, the first strategy would be limited to work‐directed interventions such as modified work. Modified work can include light duty, graded work exposure, or work trial (Krause 1998). The second strategy would be interventions aiming to support the individual worker with his or her ability to cope with depression in the workplace. The third strategy would include both studies of treatment interventions which encompass work outcomes as well as studies evaluating the effect of addressing work issues as part of the treatment. Several examples are known for the first category, such as studies comparing the differential effects of pharmacotherapy on work disability in terms of workdays lost (e.g. Simon 2000). Moreover, there is only one study known to the authors that determined the effectiveness of the addition of occupational therapy to care as usual (de Vries 2003).
For depressive disorders, as opposed to physical disorders such as coronary heart disease, it is hard to distinguish enhancement of coping in the workplace (second strategy) from addressing work issues as part of the treatment (third strategy). It remains unknown whether any of these occupational health interventions are effective in reducing work disability in workers with depressive disorders. Up until now, to our knowledge, no such systematic review has been published. Therefore, we aim to evaluate the effectiveness of these interventions in employees with depressive disorders. We will only differentiate between work‐directed interventions and interventions directed at the individual worker.
Objectives
This review will evaluate the effectiveness of interventions aimed at reducing work disability in employees with depressive disorders. The effectiveness of two types of interventions will be considered:
(1) Interventions directed at the workplace (e.g. modified work)
(2) Interventions directed at the individual worker (e.g. treatment of depressive disorder or occupational therapy).
Methods
Criteria for considering studies for this review
Types of studies
All randomised controlled trials (RCTs), including cluster‐randomised trials, will be included in this review. No language restrictions will be used.
Types of participants
The population will be limited to adult (i.e. over 17 years old) workers (employees or self‐employed) with a depressive disorder. Depression as a main diagnosis will be defined as fulfilling the criteria of the Diagnostic and Statistical Manual (DSM‐IV, APA 1994), the Research Diagnostic Criteria (RDC, Spitzer 1979), or the International Classification of Disease (ICD‐10, WHO 1992) for one of the following disorders: dysthymic disorder, minor depressive disorder or major depressive disorder. Depression may also be defined as a level of depressive symptoms assessed by validated self‐report instruments, such as the Beck Depression Inventory (BDI, Beck 1987) or clinician‐rated instruments such as the Hamilton Depression Rating Scale (HDRS, Hamilton 1967), which have been published in peer‐reviewed journals. Workers with adjustment disorders will not be included in this study as this topic will be dealt with in another concurrent review (Bruinvels 2006). Comorbidity of other common mental disorders (such as anxiety disorders) may be present, although workers with bipolar disorders or depressive disorders with psychotic features will be excluded. Participants from occupational health settings, primary care or outpatient care will be included.
Types of interventions
All interventions aimed at reducing work disability will be included in this review, but interventions aimed at the workplace will be considered separately from interventions aimed at the individual. The reason for this is that the aim of the first type of intervention is to reduce work disability directly, while the aim of the second is to enhance work functioning by diminishing depressive symptoms. Examples of interventions aimed at the workplace are light duty, graded work exposure, or work trial. Workplace interventions will be categorised as:
(1) Modified working hours.
(2) Modified job tasks.
(3) A combination of modified working hours and job tasks.
Interventions aimed at the individual can be divided into:
(1) Pharmacological. Pharmacological interventions embrace any type of antidepressant medication at any dose.
(2) Psychological. Psychological interventions are restricted to cognitive‐behavioral interventions (CBT), interpersonal therapy (IPT), problem solving therapy (PST), psychodynamic therapy, counselling and occupational therapy, undertaken by qualified trained therapists.
(3) A combination of pharmacological and psychological interventions.
The comparisons necessary to achieve the review's objectives are:
(1) Intervention directed at the workplace versus no treatment or alternative intervention.
(a) Any workplace intervention versus no intervention.
(b) Any workplace intervention versus care as usual.
(c) Any workplace intervention plus care as usual versus care as usual.
(d) Workplace intervention with modified hours versus workplace intervention with modified job tasks.
(2) Intervention directed at the individual worker versus no treatment or "alternative intervention".
(a) Any antidepressant medication versus any other antidepressant medication.
(b) Any antidepressant medication versus placebo.
(c) Any antidepressant medication versus any psychological intervention.
(d) Psychological intervention combined with antidepressant medication versus psychological interventions alone.
(e) Psychological intervention combined with antidepressant medication versus antidepressant medication alone.
(f) Psychological intervention combined with antidepressant medication versus care as usual.
(g) One psychological intervention versus other psychological intervention.
(h) Psychological intervention versus no treatment or waiting‐list condition.
(i) Psychological intervention versus care as usual.
Types of outcome measures
Primary outcome
In this review, prevention of work disability is operationalised as reducing sickness absence and enhancing work functioning. The main outcome measure in this review will be days of sickness absence during the follow‐up period. Sickness absence may be extracted from the employee attendance records, the files of a compensation board, or may be self‐reported.
Secondary outcomes
(1) Employment status after a period of time (categories being "not working", "working less hours than the contract hours or having modified duties" or "working the amount of hours and having the duties as the contract hours".
(2) Work functioning or productivity. Examples of work functioning or productivity measures are the Endicott Work Productivity Scale (EWPS, Endicott 1997) and the Sheehan Disability Scale (SDS, Sheehan 1996). Only instruments that separately measure work functioning (instead of work and other activities combined) will be included.
(3) Reduction in depression (either dichotomously or continuously measured).
For the purpose of the review other outcomes such as employee satisfaction, general social functioning (not work‐specific) or quality of life scales will not be included.
Search methods for identification of studies
The first step will be to search the two CCDAN specialised registers (study‐based and reference‐based) to identify all potentially eligible studies. Both work terms as well as terms relating to depression will be used to identify these studies.
CCDANCTR‐Studies
Diagnosis = Depress* or Dysthymi* or "Mood Disorder*" or "Affective Disorder" or "Affective Symptoms"
and
Setting = work*
or
Outcomes = Work* or employ* or vocation* or occupat* or "sick days" or "Sick Leave" or "Sick Absence" or "Time Off"
CCDANCTR‐References
Keyword = Depress* or Dysthymi* or "Mood Disorder*" or "Affective Disorder" or "Affective Symptoms"
and
Free‐text = ("occupational" and (intervention* or therap* or treatment*)) and (work* or employe* or employment* or vocation* or "sick leave" or disabil* or absentee*)
The second step will be the searching of the following electronic databases: Cochrane Library CENTRAL register, MEDLINE (1966 to present), EMBASE (1988 to present), CINAHL (1982 to present) , PsycINFO (1983 to present), OSH‐ROM (Occupational Safety and Health; all databases except for MEDLINE), NHS‐EED (1994 to present), and the database of Abstracts of Reviews of Effectiveness (DARE).
In MEDLINE (Table 1), PsycINFO (Table 2), EMBASE (Table 3) and CINAHL (Table 4) and OSH‐ROM two types of terms will be used: depression‐related words (see CCDAN search strategy) combined with work‐related words and database‐specific methodological filers (see CCDAN search strategy).
| Medline: |
| Medline: |
| Embase: |
| 1 exp depression/ |
| Psycinfo |
| #62(#55 not #59) and ((explode neurotic depressive reaction/) or (explode dysthymic disorder) or ("depression (emotion)") or (explode major depression) or (explode affective disorders) or (explode recurrent depression) or (explode reactive depression)) and (#9 or #10 or #11 or #12 or #13 or #14 or #15 or #16 or #17 or #18 or #19 or #20 or #21 or #22 or #23 or #24 or #25 or #26 or #27 or #28 or #29 or #30 or #31 or #32 or #33 or #34 or #35 or #36 or #37 or #38 or #39 or #40 or #41 or #42) |
| CINAHL: |
| 1. depression/ |
Work‐related terms: work* and occupation* are sensitive single terms used to locate occupational health studies as advocated by Verbeek (Verbeek 2005). Furthermore, we selected database‐specific terms relevant to our objective from a study (Haafkens 2006) on suitable work‐related terms in searching for literature on chronic disease (rheumatoid arthritis, diabetes mellitus, hearing problems and depression) and work.
The third step will be to check the reference lists of all articles that are retrieved as full papers and of all retrieved systematic and narrative reviews in order to identify potentially eligible studies.
The fourth step will be handsearching the Journal of Occupational Rehabilitation published before 2001.
The last step will be to write to the corresponding authors of all studies that fulfil the inclusion criteria to inquire after any additional published or unpublished study that may be relevant to this review.
Data collection and analysis
Selection of studies
Identification of eligible studies will be conducted independently by two reviewers. Any disagreement about the inclusion of studies will be followed by a discussion until consensus is reached between the two reviewers. If the difference of opinion cannot be resolved, a third reviewer will be consulted. If the title and abstract provide sufficient information to decide that it does not satisfy the criteria for selection, the study will be excluded. We will exclude studies in this phase only if the study does not include patients with depressive disorders or was not a controlled intervention study. Whenever we are unsure whether sickness absence is measured, we will retrieve the full article before deciding on exclusion. The full articles of the remaining studies will then be examined by the two reviewers in order to decide which studies fulfil all inclusion criteria. The reason for exclusion at this stage will be documented. All articles in languages other than English will be translated or reviewed by a native speaker.
Data extraction and management
A data extraction form will be constructed that will enable two reviewers to extract the following data from the articles:
Methods (including concealment of allocation), participants (diagnosis and contextual information, including type of work), intervention (content, dose, duration, provider, context), outcome measures used and results for each outcome measure. Concealment of allocation will be considered adequate for psychological interventions if allocation is concealed from staff. In contrast, for pharmacological intervention, blinding of patients will be a criterion for adequacy of concealment. A small sample of the articles will be used to test whether the form is feasible according to the two reviewers.
Assessment of methodological quality of included studies
The quality of the included studies will be independently assessed by two reviewers. The procedures described in the Cochrane Collaboration Handbook will be used to assess quality (Alderson 2004). The Downs and Black checklist will be used (Downs 1998). Where necessary, authors will be contacted for more detailed information. A small sample of the articles will be used to test whether the assessment criteria are applied consistently between the two reviewers. Any disagreement about the criteria will be followed by a discussion until consensus is reached. If the difference of opinion cannot be resolved, a third reviewer will be consulted.
Data synthesis
Measures of treatment effect
Days of sickness absence during follow up will be transformed into a percentage of sickness days during follow up. Since this event will be relatively common this count data will be treated as a continuous variable. Ordinal variables using a scale of more than five categories will also be treated as a continuous variable (depression, work functioning, or productivity). For continuous variables difference in means will be presented. If meta‐analysis is appropriate, then for continuous data the standardised mean difference (with a 95% confidence interval (CI)) will be used as the summary effect measure since these outcomes are likely to be measured with different scales in the varying studies. Scales with less than five categories will be dichotomised. For dichotomous data, such as employment status and reduction in depression, risk ratios (RR, including a 95% CI) will be presented. With regard to cluster‐randomised trials, the effect measure presented in the publication will only be used if appropriate analyses are used, such as multilevel analysis, a variance components analysis, or generalised estimation equations (GEE). If this information is unavailable, then the standard error of the effect estimate will be multiplied by the square root of the design effect.
Meta‐analysis will only be considered when a group of trials is sufficiently homogeneous in terms of participants, interventions and outcomes to provide a meaningful summary. If so, then heterogeneity will be formally tested using the chi‐squared test with the P value set at 0.1. If heterogeneity is observed according to this test then the following subgroup analyses will be conducted.
(1) Subgroups of diagnosis: dysthymic disorder, minor depression, high level of depressive symptoms versus major depressive disorder.
(2) Subgroups of gender.
(3) Subgroups of co‐morbidity: present versus not present.
(4) Type of work.
Furthermore, a random effects model will be used in the meta‐analysis. Available case analysis will be used in the meta‐analysis. If the numbers of outcomes for each group (dichotomous data) or the standard deviations (continuous data) are not presented in the publication, then the authors will be contacted with a request to provide these figures. Should they be unwilling or unable to provide this information, then the standard deviations will be calculated from available information. Skewness of the primary outcome measure will be checked using the check advised in the Cochrane Handbook (section 8.5.2.11) as the highest and lowest outcome for this variable is known to exist (0% to 100%). Sensitivity analysis will be conducted to assess the robustness of the results when excluding the following:
(1) Low quality studies.
(2) Studies with skewed data.
(3) Cluster‐randomised trials
(4) Studies in which workers were a small subgroup of the study population.
Finally, a funnel plot will be produced and visually inspected by the reviewers to assess possible publication bias. If asymmetry is observed, this will be reported in the review.
| Medline: |
| Medline: |
| Embase: |
| 1 exp depression/ |
| Psycinfo |
| #62(#55 not #59) and ((explode neurotic depressive reaction/) or (explode dysthymic disorder) or ("depression (emotion)") or (explode major depression) or (explode affective disorders) or (explode recurrent depression) or (explode reactive depression)) and (#9 or #10 or #11 or #12 or #13 or #14 or #15 or #16 or #17 or #18 or #19 or #20 or #21 or #22 or #23 or #24 or #25 or #26 or #27 or #28 or #29 or #30 or #31 or #32 or #33 or #34 or #35 or #36 or #37 or #38 or #39 or #40 or #41 or #42) |
| CINAHL: |
| 1. depression/ |
