BongKyoo Choi

Sedentary work, low physical job demand, and obesity in US workers

BACKGROUND Little is known about the role of low physical activity at work (sedentary work or low physical job demand) in the increasing prevalence of obesity of US workers. METHODS This cross-sectional and secondary data analysis included 1,001 male and 1,018 female workers (age range: 32-69) from the National Survey of Midlife Development in the United States (MIDUS) II study (2004-2006). Sedentary work and physical job demand were measured by questionnaire items. Total obesity (based on body mass index) and central obesity (based on waist circumference) were defined using WHO criteria. RESULTS After controlling for covariates (socio-demographic, psychosocial working conditions, health status, and health behaviors), sedentary work, low physical job demand, or their combination increased the risk for total and central obesity in male workers, particularly when they worked longer than 40 hr per week. Sedentary work marginally increased the risk for total and central obesity in female workers. CONCLUSIONS Low physical activity at work is a significant risk factor for total and central obesity in middle-aged US male workers.

Sleeping problems as a risk factor for subsequent musculoskeletal pain and the role of job strain: Results from a one-year follow-up of the Malmö shoulder neck study cohort

Background: The role of sleeping problems in the causal pathway between job strain and musculoskeletal pain is not clear.Purpose: To investigate the impact of sleeping problems and job strain on the one-year risk for neck, shoulder, and lumbar pain.Method: A prospective study, using self-administered questionnaires, of a healthy cohort of 4,140 vocationally active persons ages 45–64, residing in the city of Malmö.Results: At follow-up, 11.8% of the men and 14.8% of the women had developed pain. The odds ratios (OR) for pain at follow-up and sleeping problems at baseline were 1.72 (95% CI: 1.13–2.61) in men and 1.91 (1.35–2.70) in women. Regarding exposure to job strain, ORs were 1.39 (0.94–2.05) for men and 1.63 (1.18–2.23) for women. These statistically significant risks remained so when controlled for possible confounding. A modest synergistic effect was noted in women with concurrent sleeping problems and job strain, but not in men.Conclusion: One in 15–20 of all new cases of chronic pain in the population could be attributed to sleeping problems. No evidence was found for a causal chain with job strain leading to musculoskeletal pain by the pathway of sleeping problems.

Exploring Occupational and Health Behavioral Causes of Firefighter Obesity: A Qualitative Study

BACKGROUND Firefighters, as an occupational group, have one of the highest prevalence rates of obesity. A qualitative study investigated occupational and health behavioral determinants of obesity among firefighters. METHODS Four focus groups were conducted with firefighters of every rank as Phase I of the FORWARD study which was designed to assess health behavioral and occupational characteristics related to obesity in firefighters. RESULTS Analysis revealed five main themes of central importance to firefighters: (1) fire station eating culture; (2) night calls and sleep interruption; (3) supervisor leadership and physical fitness; (4) sedentary work; and (5) age and generational influences. CONCLUSION The results showed a strong interrelationship between occupational and health behavioral causes of obesity in firefighters. The relevance of these qualitative findings are discussed along with the implications for future obesity interventions with firefighters.

Psychosocial working conditions and exhaustion in a working population sample of Swedish middle-aged men and women

BACKGROUND Exhaustion is a concept of interest for both occupational health research and stress-disease theory research. The aim of the present study was to explore associations between chronic stressors, in terms of psychosocial working conditions, and exhaustion in a Swedish middle-aged population sample. METHODS A vocationally active population sample of the Malmö Shoulder and Neck Study cohort, comprising 2555 men and 2466 women between 45 and 64 years of age, was used. Psychosocial working conditions, assessed by means of the demand-control-support model, were measured longitudinally with a 1-year interval. Exhaustion was assessed by the SF-36 vitality scale and measured at follow-up, yielding a cross-sectional study design. RESULTS Exhaustion was twice as common in women as in men. High psychological job demands, low job control and low job support were independently associated with exhaustion in both men and women. These associations remained after controlling for a variety of potential confounders and mediators, including socio-demographic factors, lifestyle factors, musculoskeletal pain, disease, other work-related factors (including physical workload) and non-work-related factors. High demands in combination with low control (job strain), and job strain combined with low job support (iso-strain), increased the risk for exhaustion. CONCLUSION Psychosocial working conditions seem to contribute to exhaustion in middle-aged men and women. Future research should include exploration of exhaustion as a possible mediator between work stress and disease, as well as exploration of other chronic stressors, including non-work-related stressors, regarding their effects on exhaustion in men and women.

Synergistic interaction effect between job control and social support at work on general psychological distress

PurposeLittle is known about the interaction between job control and social support at work on common mental disorders. To examine whether there is a synergistic interaction effect between job control and social support at work on general psychological distress and whether it differs by the level of job demands.MethodsAbout 1,940 male and female workers from the Malmö Shoulder and Neck Study were chosen for this cross-sectional study. Job control, social support at work, and job demands were measured by the Swedish version of the Job Content Questionnaire, and general psychological distress was assessed by the General Health Questionnaire.ResultsA significant excessive risk increase for general psychological distress was observed when workers had both low job control and low social support at work in both men and women. The synergistic effect was stronger in women, when job demands were low (Rothman’s synergy index was 2.16 vs. 1.51 when job demands were high). However, in male workers, while a strong synergistic effect between job control and social support at work was found when job demands were low (synergy index was 9.25), there was an antagonistic effect when job demands were high (synergy index was 0.52).ConclusionsThere was a synergistic interaction effect between job control and social support at work on general psychological distress, but the synergistic effect or its effect size differed by the level of job demands and gender. An atomic, additive approach to the risk assessment of the psychosocial work characteristics on common mental disorders could be misleading or lead to a risk underestimation.

A cross-national study on the multidimensional characteristics of the five-item psychological demands scale of the job content questionnaire

Background: The five-item psychological demands scale of the Job Content Questionnaire (JCQ) has been assumed to be one-dimensional in practice. Purpose: To examine whether the scale has sufficient internal consistency and external validity to be treated as a single scale, using the cross-national JCQ datasetsfrom the United States, Korea, and Japan. Method: Exploratory factor analyses with 22 JCQ items, confirmatory factor analyses with the five psychological demands items, and correlations analyses with mental health indexes. Results: Generally, exploratory factor analyses displayed the predicted demand/ control/support structure with three and four factors extracted. However, at more detailed levels of exploratory and confirmatory factor analyses, the demands scale showed clear evidence of multi-factor structure. The correlations of items and subscales of the demands scale with mental health indexes were similar to those of the full scale in the Korean and Japanese datasets, but not in the U.S. data. In 4 out of 16 sub-samples of the U.S. data, several significant correlations of the components of the demands scale with job dissatisfaction and life dissatisfaction were obscured by the full scale. Conclusion: The multidimensionality of the psychological demands scale should be considered in psychometric analysis and interpretation, occupational epidemiologic studies, and future scale extension.

Exploring Occupational and Behavioral Risk Factors for Obesity in Firefighters: A Theoretical Framework and Study Design

Firefighters and police officers have the third highest prevalence of obesity among 41 male occupational groups in the United States (US). However, few studies have examined the relationship of firefighter working conditions and health behaviors with obesity. This paper presents a theoretical framework describing the relationship between working conditions, health behaviors, and obesity in firefighters. In addition, the paper describes a detailed study plan for exploring the role of occupational and behavioral risk factors in the development of obesity in firefighters enrolled in the Orange County Fire Authority Wellness Fitness Program. The study plan will be described with emphasis on its methodological merits: adopting a participatory action research approach, developing a firefighter-specific work and health questionnaire, conducting both a cross-sectional epidemiological study using the questionnaire and a sub-study to assess the validity of the questionnaire with dietary intake and physical activity measures, and evaluating the strengths and weaknesses of the body mass index as an obesity measure in comparison to skinfold-based percent body fat. The study plan based on a theoretical framework can be an essential first step for establishing effective intervention programs for obesity among professional and voluntary firefighters.

Cross-language differential item functioning of the job content questionnaire among European Countries: The JACE study

BackgroundLittle is known about cross-language measurement equivalence of the job content questionnaire (JCQ)PurposeThe purposes of this study were to assess the extent of cross-language differential item functioning (DIF) of the 27 JCQ items in six languages (French, Dutch, Belgian-French, Belgian-Dutch (Flemish), Italian, and Swedish) from six European research centers and to test whether its effects on the scale-level mean comparisons among the centers were substantial or not.MethodA partial gamma coefficient method was used for statistical DIF analyses where the Flemish JCQ was the reference for other language versions. Additionally, equivalence between the Flemish and Dutch translations was subjected to a judgmental review.ResultsOn average, 36% to 39% of the total tested items appeared to be cross-language DIF items in the statistical analyses. The judgmental review indicated that half of the DIF items may be associated with translation difference. The impacts of the DIF items on the mean comparisons of the JCQ scales between the centers were non-trivial: underestimated skill discretion (Milan), underestimated decision authority (Leiden), underestimated psychological demands (Milan women), and incomparable coworker support (Gothenburg 95).ConclusionCross-language DIF of the JCQ among European countries should be considered in international comparative studies on psychosocial job hazards using JCQ scales.

Occupation-differential construct validity of the Job Content Questionnaire (JCQ) psychological job demands scale with physical job demands items: a mixed methods research.

The construct validity of the Job Content Questionnaire (JCQ) psychological demands scale in relationship to physical demands has been inconsistent. This study aims to test quantitatively and qualitatively whether the scale validity differs by occupation. Hierarchical clustering analyses of 10 JCQ psychological and physical demands items were conducted in 61 occupations from two datasets: one of non-faculty workers at a university in the United States (6 occupations with 208 total workers) and the other of a Belgian working population (55 occupations with 13,039 total workers). The psychological and physical demands items overlapped in 13 of 61 occupation-stratified clustering analyses. Most of the overlaps occurred in physically-demanding occupations and involved the two psychological demands items, ‘work fast’ and ‘work hard’. Generally, the scale reliability was low in such occupations. Additionally, interviews with eight university workers revealed that workers interpreted the two psychological demands items differently by the nature of their tasks. The scale validity was occupation-differential. Practitioner Summary: The JCQ psychological job demands scale as a job demand measure has been used worldwide in many studies. This study indicates that the wordings of the ‘work fast’ and ‘work hard’ items of the scale need to be reworded enough to differentiate mental and physical job demands as intended, ‘psychological.’

Very Long (> 48 hours) Shifts and Cardiovascular Strain in Firefighters: a Theoretical Framework.

Shift work and overtime have been implicated as important work-related risk factors for cardiovascular disease (CVD). Many firefighters who contractually work on a 24-hr work schedule, often do overtime (additional 24-hr shifts) which can result in working multiple, consecutive 24-hr shifts. Very little research has been conducted on firefighters at work that examines the impact of performing consecutive 24-hr shifts on cardiovascular physiology. Also, there have been no standard field methods for assessing in firefighters the cardiovascular changes that result from 24-hr shifts, what we call “cardiovascular strain”. The objective of this study, as the first step toward elucidating the role of very long (> 48 hrs) shifts in the development of CVD in firefighters, is to develop and describe a theoretical framework for studying cardiovascular strain in firefighters on very long shifts (i.e., > 2 consecutive 24-hr shifts). The developed theoretical framework was built on an extensive literature review, our recently completed studies with firefighters in Southern California, e-mail and discussions with several firefighters on their experiences of consecutive shifts, and our recently conducted feasibility study in a small group of firefighters of several ambulatory cardiovascular strain biomarkers (heart rate, heart rate variability, blood pressure, salivary cortisol, and salivary C-reactive protein). The theoretical framework developed in this study will facilitate future field studies on consecutive 24-hr shifts and cardiovascular health in firefighters. Also it will increase our understanding of the mechanisms by which shift work or long work hours can affect CVD, particularly through CVD biological risk factors, and thereby inform policy about sustainable work and rest schedules for firefighters.