Exploring expected and perceived facilitators and barriers of an indicated prevention strategy to prevent future long-term sickness absence; a qualitative study among employers and employees.

BACKGROUND: An indicated prevention strategy (IPS), consisting of a screening questionnaire and early treatment, was found to be effective for the prevention of future long-term sickness absence (LTSA) in two large Dutch RCT's. This IPS aims to detect employees who have a high risk to become absent, and subsequently offer them early treatment. Despite the overall effectiveness, only a few companies have implemented this strategy so far. This suggests that companies may not be convinced of the (cost) effectiveness of this strategy yet. In companies where IPS has been implemented, screenings uptake and adherence to early treatment appeared to be moderate, indicating that both employees and employers might perceive barriers. METHODS: The aim of this qualitative study was to explore the expected and perceived facilitators and barriers for the implementation of the IPS. Semi-structured interviews were conducted with 9 employers and 11 employees (acquainted and unacquainted with IPS) from large companies. Purposive sampling was used to recruit participants. All interviews were transcribed and analyzed thematically. RESULTS: The employers believed they were primarily responsible for psychological and work-related health complaints and SA, while the employees felt responsible for health complaints related to their lifestyle. According to the employees, the responsibility of the employer was solely related to work-related health. This finding exposed a relation with the health culture, which was solely based on creating a safe work environment, omitting psychological health issues. The efficacy of this IPS regarding reducing SA was estimated positive, however, the efficacy regarding LTSA was questioned. Fear of a privacy breach was often mentioned by the respondents as an important barrier. CONCLUSIONS: This study showed that the health culture within a company may be important for the perceived responsibility towards SA and health. A health culture which primarily focuses on physical complaints may raise barriers for the adoption and implementation of this preventive strategy. Participant' perceptions of the nature of LTSA and the fact that not all participants were familiar with the exact content and phasing of IPS may have doubted the efficacy regarding LTSA. This study provides important clues for future and improved implementation of IPS.

Cardiovascular Morbidity and Mortality Among Working Individuals With Rheumatic Disease: Results From a Large Prospective Cohort Study.

BACKGROUND: Cardiovascular comorbidities are common in rheumatic diseases and are associated with an increased mortality risk but have not been studied in a working population, with less severe disease. Also, the impact of premature cardiovascular mortality on work participation has been neglected until now. OBJECTIVES: The objectives of this study were to evaluate the cardiovascular risk in working individuals with inflammatory rheumatic diseases and to explore whether cardiovascular morbidity and mortality are associated with decreased work participation in this population. METHODS: Employees from 45 companies in The Netherlands (n = 12,140) were prospectively followed up from 1998 onward by annual questionnaires. Data covering 10 years of follow-up was available (1998-2008) for rheumatic and cardiovascular morbidities. Self-reported rheumatic and cardiovascular diseases were verified by clinical review in hospital records in a subsample living in 1 specific region of The Netherlands. Information on the vital status was obtained by linking our records to national registries. Cox proportional hazards models were used to determine the contribution of cardiovascular comorbidity on mortality, with adjustment for confounders. RESULTS: In the sample verified by clinical review, the 10-year risk of developing cardiovascular diseases tended to be increased in workers with inflammatory rheumatic diseases (n = 17) at baseline (relative risk, 2.30; 95% confidence interval [CI], 0.91-5.81) and was significantly increased in those with gout (n = 18) at baseline (relative risk, 3.64; 95% CI, 1.64-8.09) as compared with those without inflammatory rheumatic diseases or gout, respectively. Gout (n = 31; hazard ratio, 4.19; 95% CI, 1.33-13.25) and cardiovascular diseases (n = 206; hazard ratio, 2.19; 95% CI, 1.24-3.84) were significantly related to 10-year mortality. No deaths had occurred in individuals with inflammatory rheumatic diseases during follow-up. CONCLUSIONS: In this study, gout was significantly associated with cardiovascular comorbidity and mortality, but inflammatory rheumatic diseases were not. Decreased work participation in workers with gout and potentially inflammatory rheumatic diseases can be expected because of an increased morbidity but not mortality risk.

Cancer risk among tetrafluoroethylene synthesis and polymerization workers.

Tetrafluoroethylene (TFE), a compound used for the production of fluorinated polymers including polytetrafluoroethylene, increases the incidence of liver and kidney cancers and leukemia in rats and mice. This is the first time the cancer risk in humans has been explored comprehensively in a cohort mortality study (1950-2008) that included all polytetrafluoroethylene production sites in Europe and North America at the time it was initiated. A job-exposure matrix (1950-2002) was developed for TFE and ammonium perfluoro-octanoate, a chemical used in the polymerization process. National reference rates were used to calculate standardized mortality ratios (SMRs) and 95% confidence intervals. Among 4,773 workers ever exposed to TFE, we found a lower rate of death from most causes, as well as increased risks for cancer of the liver (SMR = 1.27; 95% confidence interval: 0.55, 2.51; 8 deaths) and kidney (SMR = 1.44; 95% confidence interval: 0.69, 2.65; 10 deaths) and for leukemia (SMR = 1.48; 95% confidence interval: 0.77, 2.59; 12 deaths). A nonsignificant upward trend (P = 0.24) by cumulative exposure to TFE was observed for liver cancer. TFE and ammonium perfluoro-octanoate exposures were highly correlated, and therefore their separate effects could not be disentangled. This pattern of findings narrows the range of uncertainty on potential TFE carcinogenicity but cannot conclusively confirm or refute the hypothesis that TFE is carcinogenic to humans.

Prevention of long-term sickness absence and major depression in high-risk employees: a randomised controlled trial.

OBJECTIVES: To examine the efficacy of early intervention on the prevention of long-term sickness absence and major depression among employees at high risk of future sickness absence and with mild to severe depressive complaints. METHODS: Randomised controlled trial conducted among employees working in an office environment. 139 employees were identified both at high risk of future sickness absence and with mild to severe depressive complaints through screening. Subsequently, they were randomly assigned to the intervention group (n = 69) or the control group (n = 70). Objective sickness absence was analysed at 12 and 18 months of follow-up. Depressive complaints were assessed by the Beck Depression Inventory (BDI-II) at baseline, and at 6 and 12 months of follow-up. RESULTS: Intention-to-treat analyses showed a significant difference in total sickness absence duration between the intervention (27.5 calendar days (SD 44.7)) and control group (50.8 days (SD 75.8)) over 12 months of follow-up, a reduction of 46% (p = 0.017). The intervention group showed a non-significantly lower proportion of long-term sickness absence spells compared with the control group (p = 0.127). Statistically significant and clinically relevant differences in depressive complaints were found after both 6 months (p = 0.001) and 12 months (p = 0.005) of follow-up, in favour of the intervention group. Relative risk reductions (RRR) were 19.2% and 19.8% respectively. Sickness absence data were available for all participants over 18 months of follow-up. Questionnaire data were available for 99 (at 6 months) and 90 participants (at 12 months). No adverse events or side effects occurred. CONCLUSIONS: Early intervention in employees with mild to severe depressive complaints and high risk of future long-term sickness absence proved to be effective in preventing/reducing both sickness absence and depressive complaints.

Improving measurement models in clinical epidemiology: time to move beyond the inherent assumption of an underlying reflective measurement model.

OBJECTIVES: The nature of a construct's measurement model, most decisively being predominantly reflective or formative, is essential for its development, validation, and use. Differentiating between these types of measurement models cannot be done based on statistics alone, but has to rely on expert judgment, preferably guided by checklists and theoretical assumptions. However, consideration and substantiation of the choices of the measurement models is lacking in most studies describing the validation of measurement instruments in the field of clinical epidemiology. STUDY DESIGN AND SETTING: A convenience sample of 96 clinimetric studies, published from 2017 up until May 17th, 2018 was scored on model use and (mis)specification. RESULTS: In over 50% of the identified studies in this sample, formative measurement models are considered and/or analyzed as reflective. CONCLUSION: Misspecification of formative measurement models as reflective was found to be more rule than exception. It is therefore recommended that model selection and considerations on the theoretical nature of the measurement model should be classified, motivated, and discussed, for example, by using available checklists. Hereby, it can be ensured that the appropriate measurement models and corresponding statistics are used.

The incidence of anxiety and depression among employees--the role of psychosocial work characteristics.

BACKGROUND: Anxiety and depression are prevalent among employees and are associated with functional disability and work impairment. To date, little is known about the incidence and possible risk factors for developing anxiety and depression in the working population. Study aims were to (a) determine the incidence of subclinical anxiety and depression in a general working population and (b) identify the psychosocial work characteristics associated with the onset of subclinical anxiety and depression. METHODS: This prospective study is based on 3,707 employees participating in the Maastricht Cohort Study on Fatigue at Work. Psychosocial work characteristics were measured in May 2000; anxiety and depression were measured with the Hospital Anxiety and Depression Scale in April 2002. RESULTS: The cumulative 23-month incidence for subclinical anxiety and depression was 4.6 and 3.3%, respectively. High psychological job demands increased the risk for both subsequent anxiety and depression. Moreover, low social support was predictive for the onset of anxiety, whereas job insecurity increased the risk for the onset of depression. These prospective associations were independent of potential confounding variables and the other psychosocial work characteristics. CONCLUSIONS: Adverse psychosocial work characteristics are significant predictors for the onset of subclinical anxiety and depression in the general working population. These findings encourage intervention studies testing whether modifying the psychosocial work environment reduces both anxiety and depressive symptoms among employees.

Cancer mortality in workers exposed to dieldrin and aldrin: over 50 years of follow up.

OBJECTIVE: Dieldrin and aldrin, pesticides widely used until the 1970s, have been under suspicion of being carcinogenic. In this study, overall and cause-specific mortality was assessed in a cohort of 570 employees occupationally exposed to the pesticides dieldrin and aldrin to investigate the long-term health effects, in particular carcinogenic effects. METHODS: All of the employees worked in the production plants between January 1954 and January 1970 and were followed for cause-specific mortality until 30 April 2006. Based on dieldrin levels in blood samples taken from 343 workers during the exposure period, the total intake of dieldrin was estimated for each individual subjects in the cohort. The estimated total intake ranged from 11 to 7,755 mg of dieldrin, with an average of 737 mg. RESULTS: Two hundred and twenty-six workers had died before 30 April 2006 compared with an expected number of 327.3, giving a standardized mortality ratio (SMR) of 69.0 (95% confidence interval (CI): 60.3-78.7). Overall cancer mortality was also significantly lower than expected (SMR: 76.4, 95% CI: 60.8-94.9). Also, none of the specific cancer sites showed a significant excess mortality and no association between exposure level and cancer mortality was found. CONCLUSION: The results from this study support findings from other epidemiological and recent animal studies concluding that dieldrin and aldrin are not likely human carcinogens.

Time takes us all? A two-wave observational study of age and time effects on sustainable employability.

Objectives Various cognitive and physical abilities decline with age. Consequently, sustainable employability research has focused on the labor market participation of older employees. However, it remains unclear whether age actually affects employees' work and labor-market functioning. A major complicating factor is that age effects can be distorted by time effects. That is, changes over time may not be due to aging but to some structural difference between the times of measurement. The present article aims to provide clarity by estimating age effects on sustainable employability while controlling for potential time effects. Methods Based on two-wave survey data from a sample of 2672 employees (ages 35‒65 years) multilevel regressions are estimated to analyze the effects of age and time on sustainable employability. Here, sustainable employability is operationalized as a formative construct consisting of nine dimensions, each capturing a different facet of an individual's ability to function at work and in the labor market. Results The analyses reveal that age has small effects on only two dimensions (employability and perceived health) while time affects three dimensions (fatigue, job performance, and skill gap) of sustainable employability. Moreover, for all dimensions of sustainable employability most variance exists between (61.43-84.96%) rather than within (15.04-38.57%) subjects. Conclusions These findings suggest that the process of aging has a limited effect on working individuals' capacities to function in their job and the labor market. Consequently, the focus on age in the context of sustainable employability policies and research may require reconsideration.

Handling the reflective-formative measurement conundrum: a practical illustration based on sustainable employability.

OBJECTIVES: Constructs capturing health or functioning can have reflective and/or formative measurement models. Although a construct's measurement model has extensive implications on the construction, validation, and use of a measurement instrument, measurement models are frequently wrongly or not explicitly specified. As this is likely due to a lack of guidelines, this study uses sustainable employability as an example to demonstrate a) the applicability of an adapted checklist for establishing a construct's measurement model; and b) the use of structural equation modeling to handle formative constructs. STUDY DESIGN AND SETTING: First, the checklist is applied to sustainable employability to establish its measurement model. Second, using observational self-report data from 2,544 employees, structural equation models are estimated to evaluate the structural and criterion validity of sustainable employability as a formative construct. RESULTS: The checklist demonstrates strong applicability, identifying sustainable employability as a formative construct. Model fit indices (Comparative fit indices ≥ 0.932, Tucker-Lewis indices ≥ 0.925, root mean square errors of approximation ≤ 0.034) suggest the formative measurement model for sustainable employability is valid. CONCLUSION: The checklist and structural equation modeling facilitate handling formative constructs. By establishing sustainable employability as a formative construct, individuals' long term ability to function at work can be more adequately studied and intervened upon.

Associations of fatigue and depression among fatigued employees over time: a 4-year follow-up study.

OBJECTIVE: The objective of this study was to investigate how unexplained fatigue and depression are associated over time in a sample of employees with advanced fatigue, taking physical functioning and work status into account. METHODS: Data come from a randomized trial in which 151 fatigued employees on sick leave participated. Using repeated-measures analysis, we assessed associations between fatigue and depression scores over the course of 4 years, controlling for physical functioning and work status. RESULTS: Many participants suffered from fatigue and depression that persisted in time. Depression had a strong impact on fatigue in the course of follow-up, and fatigue had a strong impact on depression. The impact of depression on fatigue increased significantly in time, but not vice versa. Physical functioning and work status did not confound the association of fatigue and depression. CONCLUSION: Fatigue and depression are strongly associated in time and might become more intertwined as time persists. One possible explanation is that depression reinforces fatigue, which suggests that treatment should be focused on all aspects of emotional well-being.

Experiences of occupational physicians with the implementation of indicated prevention for long term sickness absence.

BACKGROUND: Functioning including work participation, is an emerging challenge in occupational health. The prevention of long term sickness absence (LTSA) through a strategy involving screening and structured early consultation (preventive strategy) was proven effective and can address participation issues. Implementation of this strategy has proven difficult. OBJECTIVE: The aim of this study is to investigate the experiences of occupational physicians (OPs) delivering a structured early consultation to office workers, in order to enhance implementation of the strategy. METHODS: In this case study, a mixed method design was used. Interviews and surveys were conducted to obtain an in-depth picture of OPs experiences. RESULTS: Factors hindering implementation in relation to the OPs were difficulties in communicating the risk of future sick leave, prioritization of other tasks, maintaining a reactive approach due to work pressure, preference for prevention on the level of the work environment, privacy issues related to labeling workers to have mental or psychosocial issues, and the biomedical model being the mental model in use. CONCLUSIONS: Implementation of the preventive strategy seems to require a more profound focus on the biopsychosocial approach. Training of relevant skills is important to achieve a focus on prevention and fostering health over the lifespan.

Fostering functioning of workers: A new challenge for prevention in occupational health.

Given large changes in working conditions and society, occupational health care has to prioritize its efforts towards fostering health and functioning of workers and as such promote work participation. This requires that more emphasis is given on the application of biopsychological models in the care of workers. Although a biopsychological approach is often mentioned as essential part of occupational health care, it's application is often hampered in practice, by practical barriers and lack of practical knowledge. This is illustrated by a study that uncovered facilitating and hindering factors in the implementation process of a preventive strategy, proven effective in reducing the risk of long term sickness absence. To facilitate the use of biopsychological models in occupational health care, it is shown that setting up a training curriculum is possible, based on the International Classification of Functioning, Disability and Health (ICF) grafted on available training in evidence based practice skills is possible. Furthermore, there is a need for elaboration of the personal factors relevant for workers and the relevant work-related environmental factors to support practical application of ICF in occupational health care. A paradigm shift in occupational health care can facilitate widespread implementation of the biopsychosocial approach in occupational health and may stimulate occupational health professionals to further integrate this approach in their daily practice.

Implementing the ICF in Occupational Health; building a curriculum as an exemplary case.

BACKGROUND: This paper addresses the need for a paradigm shift from post-diagnosis tertiary care towards maintenance and promotion of health across the lifespan, for healthcare in general and in occupational healthcare specifically. It is based on the assumption that the realization of this paradigm shift may be facilitated by teaching (future) occupational health professionals to use the International Classification of Functioning, Disability and Health (ICF). OBJECTIVE: Describing the development of a an ICF based occupational health curriculum. METHODS: Grafting a training trajectory in the ICF for educating the biopsychosocial health paradigm, onto a training trajectory in the Critical Appraisal of a Topic (CAT), a method for teaching evidence based practice skills. RESULTS: The development process of the training trajectories in the master program Work, Health, and Career at Maastricht University is described as an example of an intervention for shifting the paradigm in healthcare curricula. The expected results are a shift from the biomedical towards the biopsychosocial paradigm, a reductionist approach towards a more holistic view on cases, a reactive way of working towards a more proactive work style, and from using a merely quantifiable evidence base towards using a broad evidence base. CONCLUSIONS: Incorporating the biopsychosocial paradigm into the assessment and scientific reasoning skills of students is not only valuable in occupational healthcare but might be a valuable approach for all disciplines in healthcare for which contextual factors are important e.g. rehabilitation, psychiatry and nutritional science.

Long-term efficacy of cognitive-behavioral therapy by general practitioners for fatigue: a 4-year follow-up study.

OBJECTIVE: In an earlier study, we found that cognitive-behavioral therapy (CBT) delivered by general practitioners (GPs) for fatigue among employees on sick leave was not effective after 12 months. In this study we aim to assess the long-term efficacy of CBT by GPs for fatigue. It was hypothesized that the intervention could prevent deterioration as well as relapse of fatigue complaints and relapse into absenteeism in the long term. METHODS: Patients who participated in the original randomized controlled trial were followed up 4 years later. Fatigue and absenteeism were the main outcomes. RESULTS: Fatigue and absenteeism were high in the intervention and control groups at the 4-year follow-up. There was no significant difference between the intervention group and the control group on fatigue and absenteeism. The intervention group however tended toward less-favorable outcomes as compared with the control group. CONCLUSIONS: Like that of chronic fatigue syndrome, the prognosis of less-advanced fatigue is rather poor. CBT delivered by GPs is not effective in the long term.

Vital working hour schemes: The dynamic balance between various interests.

"Balancing Interests", the theme of the 17th International Symposium on Shift Work and Working Time held in Hoofddorp, The Netherlands (September 2005), refers to the ambition to reach an optimal balance between the various aspects of shift work. Economic, ergonomic, physical, and psychosocial factors all interact in determining the impact of shift work at the individual, organizational, and societal level. It is the challenge of this multidisciplinary field of research to model all relevant factors in such a way that it will allow us to optimize the dynamic trade-off between the yield and the risk of shift work. The organizers of the 17th International Symposium and the co-editors of these proceedings are convinced that the high quality of the contributions will bring us closer to this ultimate goal.

Smoking among shift workers: More than a confounding factor.

In studies on the cardiovascular disease risk among shift workers, smoking is considered to be a confounding factor. In a study of 239 shift and 157 daytime workers, it was found that shift work was prospectively related to increased cigarette consumption, indicating that smoking might be in the causative pathway; however, the number of study subjects was too low to warrant sound conclusions. Therefore, data from the Maastricht Cohort study were used to investigate the longitudinal relation between smoking and shift work in a much larger population. In this study, a total of 12,140 employees were followed for two years by means of self-administered questionnaires. The authors compared workers who normally worked during daytime hours only (74%) with those who worked other than day shifts (26%). Logistic regression analyses were performed, adjusting for demographic factors of age, gender, and educational level to evaluate the risk of starting to smoke (n = 25) in the group of non-smoking workers and the risk of quitting (n = 318) in the group of smoking workers. Logistic regression analysis showed a significant association between shift work and taking up smoking during the two-year follow-up (odds ratio: 1.46, p = 0.03). The risk to stop smoking was somewhat lower in shift workers (odds ratio: 0.91) but not statistically significant (p = 0.5). To conclude, this study showed that, independent of educational level, shift workers are more prone to start smoking. This finding might have important implications for studies on the health effects of shift workers and for possible interventions aimed at the reduction of the excess health risk among shift workers.

Chronic bronchitis, cigarette smoking, and the subsequent onset of depression and anxiety: results from a prospective population-based cohort study.

OBJECTIVE: The authors used data from a prospective, population-based cohort study to examine: (a) whether the presence of chronic bronchitis predicts the subsequent onset of depression or anxiety, and (b) if the incidence of depressed or anxious cases was different for smokers compared with nonsmokers. MATERIALS AND METHODS: For studying the relation between chronic bronchitis and anxiety or depression, we used data from respectively 4468 and 4520 respondents. RESULTS: The number of incident anxious (19.1%, n = 17) and depressed (14.0%, n = 13) cases was highest in employees with chronic bronchitis compared with employees without respiratory complaints (4.3%, n = 189 and 3.3%, n = 145, respectively). The presence of chronic bronchitis was associated with a significant increase in anxious and depressed cases (odds ratio (OR) for anxiety = 5.09, 95% confidence interval (CI) 2.91, 8.89; OR for depression = 4.38, 95% CI 2.35, 8.16). The incidence of anxiety as well as depression was strongest in the smokers group (OR for anxiety = 8.94, 95% CI 4.08, 19.59; OR for depression = 7.56, 95% CI 3.37, 16.96). CONCLUSIONS: This prospective study shows significantly higher levels of anxiety as well as depression in employees with chronic bronchitis. Results also seem to indicate that smoking cigarettes modifies this association, resulting in an increased risk of depression and anxiety in employees with chronic bronchitis who smoke.

The impact of a nationwide introduction of new drugs and a treatment protocol for glaucoma on the number of glaucoma surgeries.

PURPOSE: To study the trend in number of glaucoma surgeries, and the influence hereon of the introduction of new glaucoma medication, reimbursement of its costs, and the introduction of a treatment protocol. METHODS: Out of the Dutch Health Care Registration, all open angle glaucoma and ocular hypertension patients aged 20 years and older, who underwent glaucoma surgery were selected. Over the period 1995 until 2003 the trend in the number of monthly performed glaucoma surgeries was described by LOESS spline procedure. RESULTS: From 1995 until 2003, 15,888 surgeries were included. Overall mean age was 67.5 years (SD 13.0). Mean age declined by 0.29 year per year (95% CI, 0.21-0.37). In 1995 and 1996 the number of yearly performed glaucoma surgeries was approximately 2400. From 1997 onwards this number started to decrease, resulting in a 45% decrease in the year 2000. From 2000 on the number of surgeries stabilized at approximately 1350 per year. In 1999 the total number of prescriptions rose by 20% compared with 1998, and then stabilized. In 2002, 48% of the prescriptions were prescriptions for new medication. CONCLUSION: The number of glaucoma surgeries in the Netherlands almost halved over a 3.5-year period, most likely due to the introduction of new medications. In the remaining study period the number leveled off. From the present data a substitution effect and not merely a postponement of glaucoma surgeries may be suggested, providing additional evidence that a sustained reduction in the number of glaucoma surgeries was reached in the studied period.

Approaches for predicting long-term sickness absence. Re: Schouten et al. "Screening manual and office workers for risk of long-term sickness absence: cut-off points for the Work Ability Index".

We read with much interest the article of Schouten et al (1) on identifying workers with a high risk for future long-term sickness absence using the Work Ability Index (WAI). The ability to identify high-risk workers might facilitate targeted interventions for such workers and, consequently, can reduce sickness absence levels and improve workers' health. Earlier studies by both Tamela et al (2), Kant et al (3), and Lexis et al (4) have demonstrated that such an approach, based on the identification of high-risk workers and a subsequent intervention, can be effectively applied in practice to reduce sickness absence significantly. The reason for our letter on Schouten et al's article is twofold. First, by including workers already on sick leave in a study predicting long-term sick leave will result in an overestimation of the predictive properties of the instrument and biased predictors, especially when also the outcome of interest is included as a factor in the prediction model. Second, we object to the use of the term "screening" when subjects with the condition screened for are included in the study. Reinforced by the inclusion of sickness absence in the prediction model, including workers already on sick leave will shift the focus of the study findings towards the prediction of (re)current sickness absence and workers with a below-average return-to-work rate, rather than the identification of workers at high risk for the onset of future long-term sickness absence. The possibilities for prevention will shift from pure secondary prevention to a mix of secondary and tertiary prevention. As a consequence, the predictors of the model presented in the Schouten et al article can be used as a basis for tailoring neither preventive measures nor interventions. Moreover, including the outcome (sickness absence) as a predictor in the model, especially in a mixed population including workers with and without the condition (on sick leave), will result in biased predictors and an overestimation of the predictive value. A methodological approach of related issues is provided in the works of Glymour et al (5) and Hamilton et al (6). This phenomenon is even more clearly illustrated by the predictive properties of the workability index, as described by Alavinia et al (7, page 328), which reported that "when adjusted for individual characteristics, lifestyle factors, and work characteristics, two dimensions of the WAI were significant predictors for both moderate and long durations of sickness absence: (i) the presence of sickness absence in the past 12 months prior to the medical examination and (ii) experienced limitations due to health problems." So, when applied to the study by Schouten et al (1), this means that most of the predictive value would be related to the factors "sickness absence in the past 12 months". In addition, we object to the use of the term "screening" in the Schouten et al study as it includes workers with the intended outcome (long-term sickness absence). One can identify three separate aims to study the longitudinal association between risk factors and subsequent long-term sickness absence: (i) to establish causal risk factors for long-term sickness absence, often to find clues for primary preventive strategies (beyond the scope here); (ii) to identify high-risk workers who are still at work and might benefit from an intervention before sickness absence occurs (secondary prevention); and (iii) to identify workers on sick leave who might suffer a below-average return-to-work rate or have a high risk for the recurrence of (long-term) sickness absence and might benefit from intensification or optimization of the return-to-work process (tertiary prevention). In this light, one needs to separate screening instruments from predictive instruments and reserve the term "screening" for the situation as defined by Wilson and Junger (8, page 7): "The object of screening for disease is to discover those among the apparently well who are in fact suffering from disease" (ie, situations of secondary prevention). This means that, when applying this definition on long-term sickness absence under the precondition that the individuals are still at work, screening enables the identification of high-risk individuals in the early "stages" of a "disease" that can progress into long-term sickness absence. In the case of the Schouten et al study, the population at risk, as derived from their predictive instrument, consists of workers with and without sickness absence, and as such excludes the use of the term "screening" in this case. To conclude, we have substantiated that, in addition to correct usage of the term "screening", careful selection of the study population, predictors and most importantly the aim of the predictive model are essential in the process of developing predictive instruments aimed at identifying workers at high risk of long-term sickness absence. Two fundamentally different approaches are possible. One approach aims at identifying workers on sick leave with either a below-average chance to return to work an/or a high risk for a successive episode of long-term sickness absence. From a methodological and practical point of view, such an instrument should be developed and validated among workers already on sick leave. A second approach aims at identifying workers who are still at work but at high risk for future long-term sickness absence. To develop and validate such an instrument, a study sample where workers already on sick leave are excluded is a prerequisite. Such instruments fit in a pro-active approach of preventing future sickness absence, where an early intervention can be offered to those workers with an increased risk for future sickness absence.