Development and internal validation of prediction models for colorectal cancer survivors to estimate the 1-year risk of low health-related quality of life in multiple domains.

BACKGROUND: Many colorectal cancer (CRC) survivors experience persisting health problems post-treatment that compromise their health-related quality of life (HRQoL). Prediction models are useful tools for identifying survivors at risk of low HRQoL in the future and for taking preventive action. Therefore, we developed prediction models for CRC survivors to estimate the 1-year risk of low HRQoL in multiple domains. METHODS: In 1458 CRC survivors, seven HRQoL domains (EORTC QLQ-C30: global QoL; cognitive, emotional, physical, role, social functioning; fatigue) were measured prospectively at study baseline and 1 year later. For each HRQoL domain, scores at 1-year follow-up were dichotomized into low versus normal/high. Separate multivariable logistic prediction models including biopsychosocial predictors measured at baseline were developed for the seven HRQoL domains, and internally validated using bootstrapping. RESULTS: Average time since diagnosis was 5 years at study baseline. Prediction models included both non-modifiable predictors (age, sex, socio-economic status, time since diagnosis, tumor stage, chemotherapy, radiotherapy, stoma, micturition, chemotherapy-related, stoma-related and gastrointestinal complaints, comorbidities, social inhibition/negative affectivity, and working status) and modifiable predictors (body mass index, physical activity, smoking, meat consumption, anxiety/depression, pain, and baseline fatigue and HRQoL scores). Internally validated models showed good calibration and discrimination (AUCs: 0.83-0.93). CONCLUSIONS: The prediction models performed well for estimating 1-year risk of low HRQoL in seven domains. External validation is needed before models can be applied in practice.

The Impact of Physical Work Demands on Need for Recovery, Employment Status, Retirement Intentions, and Ability to Extend Working Careers: A Longitudinal Study Among Older Workers.

OBJECTIVE: Prospectively investigating whether different approaches of physical work demands are associated with need for recovery (NFR), employment status, retirement intentions, and ability to prolong working life among older employees from the industry and health care sector. METHODS: A subsample from the Maastricht Cohort Study was studied (n = 1126). Poisson, Cox, and logistic regression analyses were performed to investigate outcomes. RESULTS: Perceiving physical work demands as strenuous was associated with higher NFR. Continuous physical strain was associated with being out of employment 4 years later. Employees with the highest amount of physical work demands perceived they were less able to prolong working life, although no significant associations between physical work demands and retirement intentions were found. CONCLUSIONS: Overall, physical work demands were associated with adverse outcomes, with divergent insights for the different approaches of physical work demands.

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.

The applicability of the international classification of functioning, disability, and health to study lifestyle and quality of life of colorectal cancer survivors.

BACKGROUND: Well-designed studies on lifestyle and health-related quality of life (HRQoL) in colorectal cancer survivors based on a biopsychosocial instead of a traditional biomedical approach are warranted. We report on the applicability of the International Classification of Functioning, Disability, and Health (ICF) as useful biopsychosocial framework to improve research on how lifestyle influences colorectal cancer survivors' HRQoL, using the Energy for life after ColoRectal cancer (EnCoRe) study as an example. METHODS: The ICF was used to develop a conceptual model for studying lifestyle and colorectal cancer survivors' HRQoL, by identifying relevant factors from literature and mapping them within the ICF. Subsequently, this model was used for selection of measurement instruments and biomarkers. By linking meaningful concepts within selected measures to the ICF, we could assess the ICF coverage of our developed conceptual model. RESULTS: Within selected measures, 450 meaningful concepts were identified, of which 88% were linked to the ICF. The linking process resulted in 132 distinctive ICF categories assigned (38% within "Body Functions," 2% within "Body Structures," 46% within "Activities and Participation," and 14% within "Environmental Factors"). CONCLUSIONS: The selected EnCoRe study measures broadly cover ICF domains relevant to colorectal cancer survivors, stressing the relevance of using a biopsychosocial approach for studying this population's HRQoL. IMPACT: The developed conceptual model will guide data analyses and interpretation, and facilitate early transfer of results for development, evaluation, and implementation of personalized multidisciplinary lifestyle interventions. We recommend the ICF as an invaluable framework for improving the quality and scope of HRQoL studies.

Different approaches to estimate exposure to work stressors, using repeated measurements, and the association with cardiovascular disease.

OBJECTIVE: To explore the stability of exposure to work stressors over time and to examine the impact of different approaches of estimating exposure on the cardiovascular disease (CVD) risk estimation. METHODS: The Maastricht Cohort Study-Work Stressor Score was used to assess work stressors at three consecutive time points among 6154 employees participating in the Maastricht Cohort Study. Incident CVD was assessed with questionnaires. Five approaches were used to estimate exposure as, for example, cumulative exposure above a cutoff point, total exposure, and average exposure. RESULTS: The correlation between the work stressor scores assessed at the first and third time point was 0.58. Employees with a stable exposure above the highest quartile had a fully adjusted hazard ratio of 1.58 (95% confidence interval, 0.93 to 2.72). CONCLUSION: Employees with a stable exposure above the highest quartile score during a minimum of 2 years might have the highest relative CVD risk.

Screening questionnaire Balansmeter proved successful in predicting future long-term sickness absence in office workers.

OBJECTIVE: To develop and validate a screening instrument to identify employees at high risk for future long-term sickness absence. STUDY DESIGN AND SETTING: The instrument was developed (n=5,601) and internally validated (n=3,383) through data analyses of the Maastricht Cohort Study, among a group of office workers not absent from work. External validation was performed in a cohort of 3,895 bank employees. RESULTS: The screening instrument, Balansmeter, captures 34 questions on demographics, work environment, private situation, (mental) health, and sickness absence history. The Balansmeter showed good predictive values for future sickness absence (>28 days) in men (internal validation relative risk [RR] 4.69 [95% confidence interval (CI): 2.74, 8.02]; external validation RR 3.90 [95% CI: 2.35, 6.45]) and women (internal validation RR 4.16 [95% CI: 2.05, 8.43]; external validation RR 2.62 [95% CI: 1.44, 4.77]). CONCLUSION: It is possible to predict future sickness absence. The Balansmeter can be considered a valuable screening instrument.

Mortality patterns among workers exposed to acrylamide: updated follow up.

OBJECTIVE: The objective of this study was to update the mortality experience of a cohort of workers with and without potential exposure to acrylamide (AMD) at three U.S. plants (n = 8508) and one plant in The Netherlands (n = 344). METHODS: We computed standardized mortality ratios (SMRs) using national and local rates and modeled internal cohort rates to assess site-specific cancer risks by demographic and work history factors and several exposure indicators for AMD. RESULTS: For the 1925-2002 study period, we observed both deficit and excess overall mortality risks among the U.S. cohort for cancer sites implicated in experimental animal studies: brain and other central nervous system (SMR = 0.67, confidence interval [CI] = 0.40-1.05), thyroid gland (SMR = 1.38, CI = 0.28-4.02), testis and other male genital organs (SMR = 0.64, CI = 0.08-2.30); and for sites selected in earlier exploratory analyses of this cohort: respiratory system cancer (RSC) (SMR = 1.17, CI = 1.06-1.27), esophagus (SMR = 1.20, CI = 0.86-1.63), rectum (SMR = 1.25, CI = 0.84-1.78), pancreas (SMR = 0.94, CI = 0.70-1.22), and kidney (SMR = 1.01, CI = 0.66-1.46). Except for RSC, attributed earlier to muriatic acid exposure, none of the mortality excesses was statistically significant. In the Dutch cohort, we observed deficits in deaths for all sites of a priori interest. An updated analysis of our previous exploratory findings for pancreatic cancer in the U.S. cohort revealed much less evidence of a possible exposure-response relationship with AMD. CONCLUSION: AMD exposure at the levels present in our study sites was not associated with elevated cancer mortality risks.

Development of the chronic fatigue syndrome in severely fatigued employees: predictors of outcome in the Maastricht cohort study.

STUDY OBJECTIVE: To identify risk factors of the development of the chronic fatigue syndrome (CFS), the persistence or recurrence of fatigue, or recovery from fatigue in a large sample of fatigued employees. DESIGN: Analyses were based on the Maastricht cohort study (MCS), a prospective population based cohort study among more than 12 000 employees. Multiple regression models were used to identify predictors of CFS-like caseness (meeting research criteria for CFS), non-CFS fatigue caseness, or no fatigue caseness. SETTING: The working population in the Netherlands. PARTICIPANTS: 1143 employees with medically unexplained fatigue were followed up prospectively for 44 months. MAIN RESULTS: At 44 month follow up, 8% of the employees were CFS-like cases (none of who reported to have received a CFS diagnosis), 40% were non-CFS fatigue cases, and 52% were no longer fatigue cases. Factors that predicted CFS-like caseness compared with non-CFS fatigue caseness were high age, exhaustion, female sex, low education, and visits to the general practitioner. Factors that predicted CFS-like caseness compared with no fatigue caseness were fatigue, exhaustion, low education, visits to the GP and occupational physician, and bad self rated health. Factors that predicted non-CFS fatigue caseness compared with no fatigue caseness were fatigue, low self perceived activity, exhaustion, anxious mood, and bad self rated health. CONCLUSIONS: Unexplained fatigue among employees in some instances is a precursor of the development of CFS. The prognostic role of self rated health suggests that prevention and treatment of chronic fatigue should be aimed at changing the perception of health or illness. Less clear is the role of health care seeking or receiving a CFS diagnosis.

An alternative trial design to overcome validity and recruitment problems in primary care research.

BACKGROUND: Although the randomized controlled trial is widely accepted as the best design to investigate new interventions, conducting a trial in primary care may present researchers with many methodological problems. OBJECTIVE: Our aim was to present an alternative trial design to overcome internal validity and recruitment problems. METHODS: In a randomized controlled trial, fatigued employees absent from work were selected among the population of an occupational health service in the South of The Netherlands. Patients randomly assigned to the experimental condition received cognitive behavioural therapy by a research GP near their home address, whereas patients in the control group received no intervention. We describe our considerations for building an alternative design. Research GPs and patients were recruited separately for the study. The pre-randomization design was applied. RESULTS: Nine research GPs performed all the interventions. Seventy-six experimental patients and 75 control patients were selected for study participation. Of these, only six patients in the experimental group and seven patients in the control group withdrew from the study at some point during follow-up. CONCLUSION: Results suggest that recruitment and randomization procedures in the alternative design served their purpose well. The alternative design proposed here might have several advantages compared with conventional trial procedures. However, our design is not widely applicable and there are ethical aspects involved that should be considered. Researchers should address their creativity when trying to minimize the problems they may encounter in designing a study.

Common infections and the role of burnout in a Dutch working population.

OBJECTIVE: To determine if burnout is a risk factor for common cold, flu-like illness and gastroenteritis. METHODS: We conducted a prospective cohort study among 12,140 employees at baseline, using three consecutive self-administered questionnaires. The Maslach Burnout Inventory-General Survey (MBI-GS) was used to define employees with burnout complaints (Level 1) and clinical burnout (Level 2). The cross-sectional relationship between burnout and the occurrence of common infections was assessed at baseline, using logistic regression analysis. Survival analysis with Cox regression was performed to study the longitudinal relationship between burnout and the subscales of the MBI-GS as risk factors for common infections. RESULTS: For both levels of burnout, an increased incidence of common infections was found at baseline. The largest effect was found for the relationship between burnout and gastroenteritis (OR: 1.86, CI: 1.57-2.21 for Level 1 and OR: 3.59, CI: 2.09-6.17 for Level 2). The longitudinal analyses showed comparable results, although less pronounced. The largest effect was again found for gastroenteritis (RR: 1.55, CI: 1.28-1.86 for Level 1 and RR: 2.09, CI: 1.09-3.98 for Level 2). For flu-like illness and common cold, we found smaller but significant effects at Level 1, but not at Level 2. The subscale "Exhaustion" was found to be the strongest predictor for infections at both levels of burnout. CONCLUSIONS: This study provides evidence for burnout as a risk factor for common infections in a large heterogeneous population. Taking into account that burnout or its subscales are not primary etiological agents for these common infections, the observed effects are large.

Prevalence of common infections among employees in different work schedules.

This study examined the prevalence of common infections among employees in different work schedules. Self-administered questionnaire data from the Maastricht Cohort Study on "Fatigue at Work" (n = 12,140) were used. Job title was used as a matching variable between day and shift workers to control for their different work environment. We used a multilevel analysis of a two-level structure, in which the individual employees (level 1) were nested within job titles (level 2), adjusted for demographics, longstanding disease, health behavior, work-related factors, fatigue and sleep quality. Results from the multilevel analyses showed that, compared to day work, shift work was associated with a higher risk for common infections, with the highest risk in three-shift workers. Compared to day work, shift work was further associated with differences in health, health behavior, sleep, fatigue and perceived job characteristics, factors that may influence the occurrence of infections and should be taken into account in future studies as well.

Job mobility, its determinants, and its effects: longitudinal data from the Maastricht Cohort Study.

This prospective study of 12,140 employees examined the effects of work characteristics and situational, psychological, and health aspects on job mobility. Before job change, the mobility group reported significantly more conflicts with the supervisor, higher physical and emotional strain, higher degree of job insecurity, lower job satisfaction, and lower degree of commitment compared with employees who did not change jobs. After job change, the mobility group reported improved autonomy, task diversity, decreased occurrence of conflicts with the supervisor, decreased physical and emotional strain, and improved training possibilities and job security than before the change. Changing jobs had a positive effect on employees with respect to job perception and job satisfaction and led to reduced fatigue and need for recovery.

Lifestyle factors as risk factors for fatigue and psychological distress in the working population: prospective results from the Maastricht Cohort Study.

We examined potentially modifiable lifestyle factors as possible risk factors for the onset of fatigue and psychological distress after 1-year follow-up among 8833 employees who participated in the prospective Maastricht Cohort Study of "Fatigue at Work." Results showed, even after adjustment for demographics, presence of disease, other lifestyle factors, psychosocial work characteristics, and psychological distress, that overweight (body mass index, 25 to 29.9) and being physically inactive during leisure time were strongly related to onset of fatigue in men, whereas underweight (body mass index, < 18.5) in women increased the risk for future fatigue. In addition, the study suggests some differential effects of lifestyle factors in the onset of psychological distress. Certainly, these modifiable factors can be targeted in interventions, either on an individual or group level, to prevent or at least reduce the risk of developing fatigue and psychological distress in the working population.

Need for recovery in the working population: description and associations with fatigue and psychological distress.

This study examined the concept of need for recovery, that is the need to recuperate from work-induced fatigue, experienced after a day of work. The study explored the relationship between need for recovery from work, prolonged fatigue, and psychological distress in the working population. A cross-sectional study was carried out. Data of the Maastricht Cohort Study on fatigue at work were used (n = 12,095). Some degree of need for recovery was found in nearly all employees. Need for recovery from work was associated with demographic, work-related, and health factors. Principal Components Analysis revealed obvious separation between need for recovery items and both fatigue items and psychological distress items, supporting the notion that need for recovery, fatigue, and psychological distress represent different underlying concepts. Although need for recovery, fatigue, and psychological distress were frequently comorbid, they also clearly occurred as separate entities.