Marnie Dobson

Job Strain and Ambulatory Blood Pressure: A Meta-Analysis and Systematic Review

We reviewed evidence of the relationship between job strain and ambulatory blood pressure (ABP) in 29 studies (1985-2012). We conducted a quantitative meta-analysis on 22 cross-sectional studies of a single exposure to job strain. We systematically reviewed 1 case-control study, 3 studies of cumulative exposure to job strain, and 3 longitudinal studies. Single exposure to job strain in cross-sectional studies was associated with higher work systolic and diastolic ABP. Associations were stronger in men than women and in studies of broad-based populations than those with limited occupational variance. Biases toward the null were common, suggesting that our summary results underestimated the true association. Job strain is a risk factor for blood pressure elevation. Workplace surveillance programs are needed to assess the prevalence of job strain and high ABP and to facilitate workplace cardiovascular risk reduction interventions.

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.

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.

Globalization, Work, and Cardiovascular Disease:

Cardiovascular disease (CVD), a global epidemic, is responsible for about 30% of all deaths worldwide. While mortality rates from CVD have been mostly declining in the advanced industrialized nations, CVD risk factors, including hypertension, obesity, and diabetes, have been on the increase everywhere. Researchers investigating the social causes of CVD have produced a robust body of evidence documenting the relationships between the work environment and CVD, including through the mechanisms of psychosocial work stressors. We review the empirical evidence linking work, psychosocial stressors, and CVD. These work stressors can produce chronic biologic arousal and promote unhealthy behaviors and thus, increased CVD risk. We offer a theoretical model that illustrates how economic globalization influences the labor market and work organization in high-income countries, which, in turn, exacerbates job characteristics, such as demands, low job control, effort-reward imbalance, job insecurity, and long work hours. There is also a growing interest in “upstream” factors among work stress researchers, including precarious employment, downsizing/restructuring, privatization, and lean production. We conclude with suggestions for future epidemiologic research on the role of work in the development of CVD, as well as policy recommendations for prevention of work-related CVD.

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.

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.

Short-term test–retest reliability of the Job Content Questionnaire and Effort–Reward Imbalance Questionnaire items and scales among professional firefighters

Relatively little is known about the short-term test–retest reliability of the Job Content Questionnaire (JCQ) and Effort–Reward Imbalance Questionnaire (ERIQ). Seventeen JCQ and six ERIQ items were qualitatively reviewed by 19 firefighters in focus groups. The items were then administered twice to 81 firefighters with a time interval of 1–8 weeks. The short-term reliability of the JCQ and ERIQ items and scales with the four-point Likert item responses was at least fair or moderate with several complementary statistical methods. It improved substantially when the four-point responses were simplified into the two (‘agree’ or ‘disagree’) responses. The JCQ psychological demands and the ERIQ effort scales were among the least reliable scales and their items were most frequently indicated by the firefighters to be clarified. The responses of professional firefighters to the JCQ and ERIQ items and scales were stable during an 8-week period, particularly when dichotomous item responses were used. Practitioner Summary: The little-known short-term reliability of the two most commonly used questionnaires for assessing psychosocial working conditions was investigated. This study indicates that the dichotomous (strongly agree/agree vs. strongly disagree/disagree) responses of firefighters to the JCQ and ERIQ items and scales are generally stable during an 8-week period.

24‐hour work shifts, sedentary work, and obesity in male firefighters

BACKGROUND Little is known about the occupational risk factors for obesity in US firefighters. METHODS 308 male California firefighters, who participated in a work and obesity project, were chosen. Working conditions were measured with a firefighter-specific occupational health questionnaire. Adiposity was clinically assessed using body mass index (BMI), waist circumference (WC), and body fat percent. RESULTS In a multivariate analysis, the prevalence of obesity by all measures was significantly higher (PRs = 3.69-6.03, P < 0.05) in the firefighters who reported seventeen to twenty-one shifts than those who reported eight to eleven shifts in the past month. Prolonged sedentary work was also a risk factor for obesity by BMI (PR = 4.18, P < 0.05). Furthermore, there was a linear dose-response relationship of obesity by BMI and WC with the number of 24-hr shifts and sedentary work. CONCLUSIONS Many additional 24-hr shifts and prolonged sedentary work substantially increased the risk for obesity in male firefighters. Am. J. Ind. Med. 59:486-500, 2016.

Recommendations for Individual Participant Data Meta-Analyses on Work Stressors and Health Outcomes: Comments on IPD-Work Consortium Papers

The IPD-Work (individual-participant data meta-analysis of working populations) Consortium has published several papers on job strain (the combination of low job control and high job demands) based on Karaseks demand-control model (1) and health-related outcomes including cardiovascular disease (CVD), cancer, obesity, diabetes as well as health-related behaviors, utilizing meta-analyses of a pooled database of study participants from 17 European cohorts. An IPD approach has some advantages over typical meta-analyses, eg, having access to all the data for each individual allows for additional analyses, compared to typical meta-analyses. However, such an approach, like other meta-analyses, is not free from errors and biases (2-6) when it is not conducted appropriately. In our review of the IPD-Work Consortiums (hereafter called the Consortium) publications of the last two years, we have identified and pointed out several conceptual and methodological errors, as well as unsubstantiated conclusions and inappropriate recommendations for worksite public health policies (6-15). However, the Consortium has not yet appropriately addressed many of the issues we have raised. Also several major errors and biases underlying the Consortium IPD meta-analysis publications have not been presented in a comprehensive way, nor have they been discussed widely among work stress researchers. We are concerned that the same errors and biases could be repeated in future IPD Consortium meta-analysis publications as well as by other researchers who are interested in meta-analyses on work stressors and health outcomes. It is possible that the inappropriate interpretations in the Consortium publications, which remained uncorrected to date, may have a negative impact on the international efforts of the work stress research community to improve the health of working populations. Recently, Dr. Töres Theorell, a principal investigator of the Consortium, responded in this journal (16) to some of our criticisms on the Consortium papers (17, 18). The purpose of this article is to discuss the methodological and substantive issues that remain to be resolved and how they could be addressed in future analyses. We provide recommendations for future IPD or typical meta-analyses on work stressors and health outcomes. Finally, we discuss the inappropriate conclusions and recommendations in the Consortium publications and provide alternative recommendations, including a comprehensive perspective on worksite intervention studies.

Job strain and obesity

We read with great interest the paper by Nyberg et al. [1] on job strain (a work stressor combining low job control and high psychological job demands) in relation to body mass index (BMI) using 13 European cohort studies. First of all, we think that the authors’ brief characterization of the existing literature as being null or mixed does not give appropriate weight to the consistency of studies that have reported significant associations between job strain and obesity. Several longitudinal studies [2–4] have supported that job strain, by itself or in combination with low social support at work, is associated with obesity in working populations. Ishizaki et al. [2] reported that whilst the cumulative (baseline and follow-up) exposure of job strain was not associated with increased BMI, it was associated with increased waist circumference in Japanese workers. Choi et al. [3] found a dose– response association between the cumulative exposure of job strain and abdominal obesity (based on waist circumference) in US workers (the MIDUS study). Brunner et al. [4] also found a dose– response association between the frequency of iso-strain (the combination of job strain and low social support at work) and obesity (based on both BMI and waist circumference) in British workers (Whitehall II Study). Furthermore, the authors reported elsewhere [5] that job strain was longitudinally associated with leisure-time physical inactivity in their European cohort data.