Commercial Driver Medical Examinations: Prevalence of Obesity, Comorbidities, and Certification Outcomes

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Objective:

The objective of this study was to assess relationships between body mass index (BMI) and comorbid conditions within a large sample of truck drivers.

Methods:

Commercial driver medical examination data from 88,246 commercial drivers between 2005 and 2012 were analyzed for associations between BMI, medical disorders, and driver certification.

Results:

Most drivers were obese (53.3%, BMI >30.0 kg/m²) and morbidly obese (26.6%, BMI >35.0 kg/m²), higher than prior reports. Obese drivers were less likely to be certified for 2 years and more likely to report heart disease, hypertension, diabetes mellitus, nervous disorders, sleep disorders, and chronic low back pain (all P < 0.0001). There are relationships between multiple potentially disqualifying conditions and increasing obesity (P < 0.0001). Morbid obesity prevalence increased 8.9% and prevalence of three or more multiple conditions increased fourfold between 2005 and 2012.

Conclusions:

Obesity is related to multiple medical factors as well as increasing numbers of conditions that limit driving certification.

Nonadherence with Employer-Mandated Sleep Apnea Treatment and Increased Risk of Serious Truck Crashes

STUDY OBJECTIVES

To evaluate the effect of an employer-mandated obstructive sleep apnea (OSA) program on the risk of serious preventable truck crashes.

METHODS

Data are from the first large-scale, employer-mandated program to screen, diagnose, and monitor OSA treatment adherence in the US trucking industry. A retrospective analysis of cohorts was constructed: polysomnogram-diagnosed drivers (OSA positive n = 1,613, OSA negative n = 403) were matched to control drivers unlikely to have OSA (n = 2,016) on two factors affecting crash risk, experience-at-hire and length of job tenure; tenure was matched on the date of each diagnosed driver's polysomnogram. Auto-adjusting positive airway pressure (APAP) treatment was provided to all cases (i.e. OSA positive drivers); treatment adherence was objectively monitored. Cases were grouped by treatment adherence: "Full Adherence" (n = 682), "Partial Adherence" (n = 571), or "No Adherence" (n = 360). Preventable Department-of-Transportation-reportable crashes/100,000 miles were compared across study subgroups. Robustness was assessed.

RESULTS

After the matching date, "No Adherence" cases had a preventable Department of Transportation-reportable crash rate that was fivefold greater (incidence rate ratio = 4.97, 95% confidence interval: 2.09, 10.63) than that of matched controls (0.070 versus 0.014 per 100,000 miles). The crash rate of "Full Adherence" cases was statistically similar to controls (incidence rate ratio = 1.02, 95% confidence interval: 0.48, 2.04; 0.014 per 100,000 miles).

CONCLUSIONS

Nontreatment-adherent OSA-positive drivers had a fivefold greater risk of serious preventable crashes, but were discharged or quit rapidly, being retained only one-third as long as other subjects. Thus, the mandated program removed risky nontreatment-adherent drivers and retained adherent drivers at the study firm. Current regulations allow nonadherent OSA cases to drive at another firm by keeping their diagnosis private.

COMMENTARY

A commentary on this article appears in this issue on page 961.

An Official American Thoracic Society Statement: The Importance of Healthy Sleep. Recommendations and Future Priorities

RATIONALE

Despite substantial public interest, few recommendations on the promotion of good sleep health exist to educate health care providers and the general public on the importance of sleep for overall health.

OBJECTIVES

The aim of this American Thoracic Society (ATS) statement is to provide a review of the current scientific literature to assist health care providers, especially pulmonologists and sleep physicians, in making recommendations to patients and the general public about the importance of achieving good quality and adequate quantity of sleep.

METHODS

ATS members were invited, based on their expertise in sleep medicine, and their conclusions were based on both empirical evidence identified after comprehensive literature review and clinical experience.

MAIN RESULTS

We focus on sleep health in both children and adults, including the impact of occupation on sleep, the public health implications of drowsy driving, and the common sleep disorders of obstructive sleep apnea and insomnia. This ATS statement also delineates gaps in research and knowledge that should be addressed and lead to new focused research priorities to advance knowledge in sleep and sleep health.

CONCLUSIONS

Good quality and quantity of sleep are essential for good health and overall quality of life; therefore a strong recommendation was made for the implementation of public education programs on the importance of sleep health.

Dietary Preferences and Nutritional Information Needs Among Career Firefighters in the United States

Background:

Considerable cardiovascular disease and cancer risk among firefighters are attributable to excess adiposity. Robust evidence confirms strong relationships between dietary patterns and the risk of chronic disease. Dietary modification is more likely to be effective when the strategy is appealing and addresses knowledge gaps.

Objective:

To assess career firefighters' diet practices and information needs, compare the relative appeal of proposed diet plans, and examine how these vary in association with body composition.

Methods:

Cross-sectional, online survey distributed to members of the International Association of Fire Fighters.

Results:

Most firefighters do not currently follow any specific dietary plan (71%) and feel that they receive insufficient nutrition information (68%), but most are interested in learning more about healthy eating (75%). When presented with written descriptions of diets without names or labels and asked to rank them in order of preference, firefighters most often rated the Mediterranean diet as their favorite and gave it a more favorable distribution of relative rankings (P<.001) compared to the Paleo, Atkins, Therapeutic Lifestyle Changes, and Esselsteyn Engine 2 (low-fat, strictly plant-based) diets. Obese respondents reported more limited nutritional knowledge (P<.001) and were more likely to feel that they received insufficient nutritional information (P=.021) than participants with normal body weight.

Conclusions:

Most career firefighters are overweight or obese and do not practice a specific diet; however, 75% want to learn more about healthy eating. Among popular dietary choices, firefighters were most receptive to a Mediterranean diet and least receptive to a strictly plant-based diet.

Incidence of sudden cardiac death in a young active population

BACKGROUND

Little is known about the burden of sudden cardiac death (SCD) among active, presumably healthy persons. We investigated the incidence of SCD among US male career firefighters.

METHODS AND RESULTS

All on-duty SCDs among US male career firefighters between 1998 and 2012 were identified from the US Fire Administration and the US National Institute for Occupational Safety and Health databases. Age-specific incidence rates (IRs) of SCD with 95% CIs were computed. A joinpoint model was fitted to analyze the trend in IR and to help estimate the annual percentage change of SCD rates over the years. The effects of seasonality were assessed through a Poisson regression model. We identified 182 SCDs; based on 99 available autopsy reports, the leading underlying cause of death was coronary heart disease (79%). The overall IR was 18.1 SCDs per 100 000 person-years. The age-specific IRs of SCD ranged between 3.8 (for those aged 18 to 24 years) and 45.2 (for those aged 55 to 64 years) per 100 000 person-years. The annual rate of SCD steadily declined over time (annual percentage change -3.9%, 95% CI -5.8 to -2.0). SCD events were more frequent during January (peak-to-low ratio 1.70; 95% CI 1.09 to 2.65). In addition, the IR was 3 times higher during high-risk duties compared with low-risk duties. IRs among firefighters were lower than those observed among the US general population and US military personnel.

CONCLUSIONS

SCD risk in this active working population is overestimated using statistics from the general population. To address public health questions among these subpopulations, more specific studies of active adults should be conducted.

Nut consumption on all-cause, cardiovascular, and cancer mortality risk: a systematic review and meta-analysis of epidemiologic studies

BACKGROUND

Recent pooled analyses supported a beneficial impact of nut consumption on health, but to our knowledge, whether nuts are associated with overall decreased mortality has not been previously reviewed.

OBJECTIVES

We aimed to systematically review prospective studies that explored the effects of nut consumption on all-cause, cardiovascular disease (CVD), and cancer mortality and quantify the size effect through a meta-analysis. We also reviewed confounding factors associated with nut consumption to assess potential clustering with other covariates.

DESIGN

We searched PubMed and EMBASE for studies published up to June 2014. Study characteristics, HRs, and 95% CIs were generated on the basis of quantitative analyses. A dose-response analysis was performed when data were available.

RESULTS

Seven studies for all-cause mortality, 6 studies for CVD mortality, and 2 studies for cancer mortality were included in the meta-analysis with a total of 354,933 participants, 44,636 cumulative incident deaths, and 3,746,534 cumulative person-years. Nut consumption was associated with some baseline characteristics such as lower body mass index and smoking status as well as increased intakes of fruit, vegetables, and alcohol. One-serving of nuts per week and per day resulted in 4% (RR: 0.96; 95% CI: 0.93, 0.98) and 27% (RR: 0.73; 95% CI: 0.60, 0.88) decreased risk of all-cause mortality, respectively, and decreased risk of CVD mortality [RR: 0.93 (95% CI: 0.88, 0.99) and 0.61 (95% CI: 0.42, 0.91), respectively]. Effects were primarily driven by decreased coronary artery disease deaths rather than stroke deaths. Nut consumption was also associated with decreased risk of cancer deaths when highest compared with lowest categories of intake were compared (RR: 0.86; 95% CI: 0.75, 0.98), but no dose-effect was shown.

CONCLUSION

Nut consumption is associated with lower risk of all-cause, CVD, and cancer mortality, but the presence of confounding factors should be taken into account when considering such findings.

Law enforcement duties and sudden cardiac death among police officers in United States: case distribution study

OBJECTIVE

To assess the association between risk of sudden cardiac death and stressful law enforcement duties compared with routine/non-emergency duties.

DESIGN

Case distribution study (case series with survey information on referent exposures).

SETTING

United States law enforcement.

PARTICIPANTS

Summaries of deaths of over 4500 US police officers provided by the National Law Enforcement Officers Memorial Fund and the Officer Down Memorial Page from 1984 to 2010.

MAIN OUTCOME MEASURES

Observed and expected sudden cardiac death counts and relative risks for sudden cardiac death events during specific strenuous duties versus routine/non-emergency activities. Independent estimates of the proportion of time that police officers spend across various law enforcement duties obtained from surveys of police chiefs and front line officers. Impact of varying exposure assessments, covariates, and missing cases in sensitivity and stability analyses.

RESULTS

441 sudden cardiac deaths were observed during the study period. Sudden cardiac death was associated with restraints/altercations (25%, n=108), physical training (20%, n=88), pursuits of suspects (12%, n=53), medical/rescue operations (8%, n=34), routine duties (23%, n=101), and other activities (11%, n=57). Compared with routine/non-emergency activities, the risk of sudden cardiac death was 34-69 times higher during restraints/altercations, 32-51 times higher during pursuits, 20-23 times higher during physical training, and 6-9 times higher during medical/rescue operations. Results were robust to all sensitivity and stability analyses.

CONCLUSIONS

Stressful law enforcement duties are associated with a risk of sudden cardiac death that is markedly higher than the risk during routine/non-emergency duties. Restraints/altercations and pursuits are associated with the greatest risk. Our findings have public health implications and suggest that primary and secondary cardiovascular prevention efforts are needed among law enforcement officers.

Duty-related risk of sudden cardiac death among young US firefighters

BACKGROUND

Little is known regarding duty-related risks for sudden cardiac death (SCD) among young firefighters.

AIMS

To investigate duty-related SCD among US firefighters aged 45 or younger.

METHODS

We collected data on duty-related SCD from the US Fire Administration (USFA) and the US National Institute for Occupational Safety and Health (NIOSH). Two physicians independently reviewed each record. The proportions of time spent by firefighters performing specific duties were estimated from a municipal department, 17 large metropolitan departments and a national database. We estimated the duty-specific relative risks (RRs) and 95% confidence intervals (95% CI) of SCD relative to non-emergency duties based on the observed deaths and the expected average proportions of time per duty.

RESULTS

The USFA recorded 205 age-eligible on-duty SCDs between 1996 and 2012; 86 (42%) of these deaths and one additional SCD were investigated by NIOSH (total n = 206). NIOSH was more likely (P < 0.001) to report on SCD associated with physical training (69% of cases were investigated) and fire suppression (57%). Compared with non-emergency duties, the risk of SCD was increased for fire suppression (RR 22.1, 95% CI 14.8-32.9), alarm response (RR 2.6, 95% CI 1.5-4.6), alarm return (RR 4.1, 95% CI 2.7-6.2) and physical training (RR 4.8, 95% CI 3.2-7.2). RRs for SCD were higher among firefighters with a pre-existing history of a cardiac condition. All 16 SCDs associated with alarm response occurred among volunteer firefighters.

CONCLUSIONS

The performance of strenuous emergency duties is strongly associated with an increased risk of SCD among young firefighters, particularly among those with a history of cardiovascular disease.

Circulating alanine transaminase (ALT) and γ-glutamyl transferase (GGT), but not fetuin-A, are associated with metabolic risk factors, at baseline and at two-year follow-up: the prospective Cyprus Metabolism Study

OBJECTIVE

To comparatively evaluate traditional liver tests and fetuin A as predictors of cardiometabolic risk, we studied associations between serum alanine transaminase (ALT), γ-glutamyl transferase (GGT), aspartate aminotransferase (AST) and fetuin-A and anthropometric, metabolic, and cardiovascular parameters cross-sectionally at baseline, and prospectively, after 2-years of follow-up.

RESEARCH DESIGN AND METHODS

616 randomly enrolled young healthy participants in the Cyprus Metabolism Study, including all 93 subjects who participated in the follow-up study 2 years after baseline assessment, were included in this study.

RESULTS

In the cross-sectional study, serum ALT and GGT were strongly correlated with anthropometric, cardiovascular, and metabolic variables, while serum AST was only correlated with waist circumference and waist-to-hip ratio. Fetuin-A was correlated with anthropometric variables, systolic blood pressure (SBP), insulin, and homeostasis model of assessment-insulin resistance (HOMA-IR) in the unadjusted model. In the fully adjusted model, both serum ALT and GGT levels remained positively correlated with total and low-density lipoprotein (LDL) cholesterol. GGT levels also remained correlated with triglycerides. ALT levels remained strongly positively correlated with insulin (r=0.17, p<.0001) and HOMA-IR (r=0.16, p=0.0001). Serum fetuin-A levels were no longer significantly correlated with any variables. Prospectively, ALT and GGT were predictors of anthropometric variables and LDL cholesterol, while baseline levels of AST and fetuin-A were not predictors of any variables at 2-year follow-up.

CONCLUSIONS

We confirmed associations of ALT and GGT levels but failed to demonstrate an independent association between fetuin-A and cardiometabolic risk factors in young healthy men. Traditional liver tests (LFTs) are thus better than fetuin-A predictors of metabolic risk factors cross-sectionally and prospectively in young healthy adults.

Modified Mediterranean diet score and cardiovascular risk in a North American working population

INTRODUCTION

Greater adherence to a Mediterranean diet is linked to lower risk for cardiovascular morbidity/mortality in studies of Mediterranean cohorts, older subjects, and/or those with existing health conditions. No studies have examined the effects of this dietary pattern in younger working populations in the United States. We investigated the effects of Mediterranean diet adherence on cardiovascular disease (CVD) biomarkers, metabolic syndrome and body composition in an occupationally active, non-Mediterranean cohort.

METHODS

A cross-sectional study in a cohort of 780 career male firefighters, ages 18 years or older, from the United States Midwest. No dietary intervention was performed. A modified Mediterranean diet score (mMDS) was developed for assessment of adherence to a Mediterranean dietary pattern from a previously administered life-style questionnaire that examined pre-existing dietary habits. Clinical data from fire department medical examinations were extracted and analyzed.

RESULTS

Obese subjects had significantly lower mMDS, and they reported greater fast/take-out food consumption (p<0.001) and intake of sweetened drinks during meals (p = 0.002). After multivariate adjustment, higher mMDS was inversely related to risk of weight gain over the past 5 years (odds ratio [OR]: 0.57, 95% confidence interval [CI]: 0.39-0.84, p for trend across score quartiles: 0.01); as well as the presence of metabolic syndrome components (OR: 0.65, 95% CI: 0.44-0.94, p for trend across score quartiles: 0.04). Higher HDL-cholesterol (p = 0.008) and lower LDL-cholesterol (p = 0.04) were observed in those with higher mMDS in linear regression after multivariate adjustment for age, BMI and physical activity.

CONCLUSIONS

In a cohort of young and active US adults, greater adherence to a Mediterranean-style dietary pattern had significant inverse associations with metabolic syndrome, LDL-cholesterol and reported weight gain, and was significantly and independently associated with higher HDL-cholesterol. Our results support the potential effectiveness of this diet in young, non-Mediterranean working cohorts, and justify future intervention studies.

Mediterranean Diet and Workplace Health Promotion

Analytical and experimental studies confirm relationships between the consumption of certain foods and cardiovascular disease, diabetes, and cancer. Mediterranean diet patterns have long been associated with a reduced risk of major diseases and many favorable health outcomes. Data from observational, longitudinal, and randomized controlled trials have demonstrated that Mediterranean-style diets can improve body mass index and body weight, reduce the incidence of diabetes mellitus and metabolic syndrome risk factors, decrease cardiovascular morbidity and coronary heart disease mortality, as well as decrease all-cause mortality. Recently, efforts have attempted to improve dietary habits in the workplace, by modifying food selection, eating patterns, meal frequency, and the sourcing of meals taken during work. Evidence supporting the Mediterranean diet and the potential cardioprotective role of healthier diets in the workplace are reviewed here, and promising strategies to improve metabolic and cardiovascular health outcomes are also provided.

High hsCRP is associated with reduced lung function in structural firefighters

BACKGROUND

To assess the association between markers of systemic inflammation and pulmonary function in a population of structural firefighters.

METHODS

We studied male career members of a large Midwestern fire department with questionnaires, spirometry, and high-sensitivity C-reactive protein (hsCRP) as a biomarker of systemic inflammation. We examined percent predicted forced expiratory volume in 1 s (FEV1 %-predicted) and forced vital capacity (FVC%-predicted).

RESULTS

Complete data were available for 401 firefighters. Higher hsCRP levels were associated with lower lung function values, after adjusting for confounding variables. Specifically, for every twofold increase in log10-hsCRP, FEV1 %-predicted decreased by a mean 1.5% (95% CI: 0.4, 2.6%) and FVC%-predicted decreased by a mean 1.4% (95% CI: 0.4, 2.3%).

CONCLUSION

hsCRP as a biomarker of systemic inflammation may indicate reduced lung function in structural firefighters.

Exposures and cross-shift lung function declines in wildland firefighters

Respiratory problems are common among wildland firefighters. However, there are few studies directly linking occupational exposures to respiratory effects in this population. Our objective was to characterize wildland fire fighting occupational exposures and assess their associations with cross-shift changes in lung function. We studied 17 members of the Alpine Interagency Hotshot Crew with environmental sampling and pulmonary function testing during a large wildfire. We characterized particles by examining size distribution and mass concentration, and conducting elemental and morphological analyses. We examined associations between cross-shift lung function change and various analytes, including levoglucosan, an indicator of wood smoke from burning biomass. The levoglucosan component of the wildfire aerosol showed a predominantly bimodal size distribution: a coarse particle mode with a mass median aerodynamic diameter about 12 μm and a fine particle mode with a mass median aerodynamic diameter < 0.5 μm. Levoglucosan was found mainly in the respirable fraction and its concentration was higher for fire line construction operations than for mop-up operations. Larger cross-shift declines in forced expiratory volume in one second were associated with exposure to higher concentrations of respirable levoglucosan (p < 0.05). Paired analyses of real-time personal air sampling measurements indicated that higher carbon monoxide (CO) concentrations were correlated with higher particulate concentrations when examined by mean values, but not by individual data points. However, low CO concentrations did not provide reliable assurance of concomitantly low particulate concentrations. We conclude that inhalation of fine smoke particles is associated with acute lung function decline in some wildland firefighters. Based on short-term findings, it appears important to address possible long-term respiratory health issues for wildland firefighters. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resources: a file containing additional information on historical studies of wildland fire exposures, a file containing the daily-exposure-severity questionnaire completed by wildland firefighter participants at the end of each day, and a file containing additional details of the investigation of correlations between carbon monoxide concentrations and other measured exposure factors in the current study.].

Obstructive sleep apnea and psychomotor vigilance task performance

BACKGROUND

Obstructive sleep apnea (OSA) is a highly prevalent disorder with considerable morbidity and mortality. Vigilance and attentiveness are often impaired in OSA patients. In occupational medicine settings, subjective reports of sleepiness are notoriously inaccurate, making the identification of objective measures of vigilance potentially important for risk assessments of fitness for duty. In order to evaluate the effects of OSA on attentiveness and vigilance, we conducted a cross-sectional study to examine the association between OSA and psychomotor vigilance task (PVT) performance.

METHODS

Patients attending sleep clinics for evaluation of possible sleep apnea were recruited. The subjects underwent either a standard overnight laboratory polysomnography or home sleep study. Subjective daytime sleepiness was assessed by Epworth sleepiness scale, and vigilance was tested using a portable device. The participants were asked to respond to the PVT signals using their dominant hand. Each PVT administration lasted 10 minutes, with stimuli signals appearing randomly at variable intervals of 2-10 seconds.

RESULTS

Mean age of the participants was 46±15 years, and mean body mass index was 34.3±9.8 kg/m(2). Participants with higher Epworth scores had worse PVT performance (P<0.05). In multivariate analyses, age, body mass index, and poor sleep efficiency (measured by Pittsburgh sleep quality index score) were associated with worse PVT performance (P<0.05). In contrast, PVT performance did not differ significantly across categories of apnea hypopnea index severity. Subgroup analysis demonstrated that women had worse performance on all PVT measures (P<0.05).

CONCLUSION

PVT performance can be utilized for risk assessments of sleepiness and may be particularly useful among populations where subjective reports are unreliable.

Sudden cardiac death among firefighters ≤45 years of age in the United States

Sudden cardiac death (SCD) is the leading cause of death in firefighters. Although on-duty SCD usually occurs in older victims almost exclusively because of coronary heart disease, no studies have examined causation across the career span. In the present retrospective case-control study, cases of SCD in young (aged ≤45 years) firefighters from the National Institute for Occupational Safety and Health fatality investigations (n = 87) were compared with 2 age- and gender-matched control groups: occupationally active firefighters (n = 915) and noncardiac traumatic firefighter fatalities (n = 56). Of the SCD cases, 63% were obese and 67% had a coronary heart disease-related cause of death. The SCD victims had much heavier hearts (522 ± 102 g) than noncardiac fatality controls (400 ± 91 g, p <0.001). Cardiomegaly (heart weight >450 g) was found in 66% of the SCD victims and conveyed a fivefold increase (95% confidence interval [CI] 1.93 to 12.4) in SCD risk. Furthermore, hypertension, including cases with left ventricular hypertrophy, increased SCD risk by 12-fold (95% CI 6.23 to 22.3) after multivariate adjustment. A history of cardiovascular disease and smoking were also independently associated with elevated SCD risk (odds ratio 6.89, 95% CI 2.87 to 16.5; and odds ratio 3.53, 95% CI 1.87 to 6.65, respectively). In conclusion, SCD in young firefighters is primarily related to preventable lifestyle factors. Obesity entry standards, smoking bans, and improved screening and/or wellness program are potential strategies to reduce SCD in younger firefighters.

Irisin mRNA and circulating levels in relation to other myokines in healthy and morbidly obese humans

OBJECTIVE

Skeletal muscle is considered to be an endocrine organ that secretes a number of myokines including follistatin (FST), myostatin (MSTN), activin A, and the newly identified irisin. Irisin's biology and function exhibit similarities with the functions of the FST-MSTN-activin A axis. It remains unknown whether there is any interplay among these molecules. The aim of this study is to examine potential associations of irisin with the FST, MSTN, and activin A axis.

METHODS

Two observational studies were performed to evaluate the associations of irisin with the other three peptides. Study A included 150 healthy males aged 18.48±0.16 years with BMI 23.18±3.75 kg/m(2). Fasting serum samples were used to measure the levels of the molecules of interest. Study B included 14 morbidly obese individuals, candidates for bariatric surgery, aged 53.14±8.93 years with BMI 50.18±10.63 kg/m(2). Blood samples were obtained after an overnight fast. Eight out of the 14 participants consented to an optional thigh biopsy during their bariatric surgery. Using the above blood and tissue samples, we measured circulating levels and muscle mRNA of irisin, FST, MSTN, and activin A.

RESULTS

We report that FNDC5 mRNA in muscle is positively correlated with FST mRNA expression in morbidly obese subjects (ρ=0.93, P<0.001). We also found that circulating irisin is positively correlated with FST circulating levels among lean subjects (ρ=0.17, P=0.05) while this association was suggestive among the obese (ρ=0.56, P=0.07).

CONCLUSION

The newly identified myokine irisin may be positively associated with FST at both the mRNA and circulating protein level.

Extreme sacrifice: sudden cardiac death in the US Fire Service

Firefighting is a hazardous profession which has claimed on average the lives of 105 US firefighters per year for the past decade. The leading cause of line-of-duty mortality is sudden cardiac death, which accounts for approximately 45% of all firefighter duty-related fatalities. Strenuous physical activity, emotional stress, and environmental pollutants all strain the cardiovascular system, and each can increase the risk of sudden cardiac events in susceptible individuals. Sudden cardiac death is more likely to occur during or shortly after emergency duties such as fire suppression, despite the fact that these duties comprise a relatively small proportion of firefighters' annual duties. Additionally, cardiac events are more likely to occur in firefighters who possess an excess of traditional risk factors for cardiovascular disease along with underlying atherosclerosis and/or structural heart disease. In this review, we propose a theoretical model for the interaction between underlying cardiovascular disease in firefighters and the multifactorial physiological strain of firefighting.

Metabolic syndrome is inversely related to cardiorespiratory fitness in male career firefighters

Cardiovascular disease (CVD) accounts for 45% of on-duty fatalities among firefighters, occurring primarily in firefighters with excess CVD risk factors in patterns resembling the metabolic syndrome (MetSyn). Additionally, firefighters have a high prevalence of obesity and sedentary behavior suggesting that MetSyn is also common. Therefore, we assessed the prevalence of MetSyn in firefighters and its association with cardiorespiratory fitness (CRF) in a cross-sectional study of 957 male career firefighters. The CRF was measured by maximal exercise tolerance testing (standard metabolic equivalent [METS]). The MetSyn was defined according to modified criteria from the Joint Scientific Statement. Group differences were compared using χ-test and logistic regression. The prevalence of MetSyn was 28.3%. Firefighters in the lowest fitness category (METS ≤ 10) had a nearly 10-fold higher prevalence of MetSyn (51.2%) compared with colleagues in the highest fitness category (METS > 14) (MetSyn prevalence 5.2%) (p value < 0.0001, adjusted for age). In multivariate regression models, every 1-unit increase in METS decreased the odds of having the MetSyn by 31% (odds ratio 0.69 [95% confidence interval 0.63-0.76] [age adjusted]), whereas age had no significant effect after adjusting for CRF. We found a high prevalence of the MetSyn in this group of career emergency responders expected to be more active, fit, and relatively younger than the general population. Moreover, there is a highly significant inverse, dose-response association with CRF. Firefighters should be given strong incentives to improve their fitness, which would decrease prevalent MetSyn, a likely precursor of on-duty CVD events and contributor to CVD burden in this population.

Bladder cancer and arsenic through drinking water: a systematic review of epidemiologic evidence

Exposure to inorganic arsenic (As) through drinking water is a major international public health issue. We carried out a systematic review of the existing literature examining the association between the risk of bladder cancer in humans and exposure to arsenic through drinking water. We searched electronic databases for studies published from January 2000 up to April 2013. Eight ecological studies, six case-control studies, four cohort studies and two meta-analyses were identified. The vast majority of the studies were carried out in areas with high arsenic concentrations in drinking water such as southwestern and northeastern Taiwan, Pakistan, Bangladesh, Argentina (Cordoba Province), USA (southeastern Michigan, Florida, Idaho) and Chile. Most of the studies reported higher risks of bladder cancer incidence or mortality in areas with high arsenic concentrations in drinking water compared to the general population or a low arsenic exposed control group. The quality assessment showed that among the studies identified, arsenic exposure was assessed at the individual level only in half of them and only three assessed exposure using a biomarker. Further, five out of eight ecological studies presented results with adjustment for potential confounders except for age; all cohort and case-control studies presented results with adjustment for cigarette smoking status in the analysis. The majority of the studies with varying study designs carried out in different areas provided evidence of statistically siginificant increases in bladder cancer risk at high concentrations of arsenic (>50 μg L(-1)). Assessing bladder cancer risk at lower exposure concentrations requires further investigation.

Exercise-induced hypertension among healthy firefighters-a comparison between two different definitions

Different studies have yielded conflicting results regarding the association of hypertensive response to exercise and cardiovascular morbidity. We compared two different definitions of exaggerated hypertensive response to exercise and their association with cardio-respiratory fitness in a population of healthy firefighters. We examined blood pressure response to exercise in 720 normotensive male career firefighters. Fitness was measured as peak metabolic equivalent tasks (METs) achieved during maximal exercise treadmill tests. Abnormal hypertensive response was defined either as systolic blood pressure ≥ 200 mm Hg; or alternatively, as responses falling in the upper tertile of blood pressure change from rest to exertion, divided by the maximal workload achieved. Using the simple definition of a 200 mm Hg cutoff at peak exercise less fit individuals (METs ≤ 12) were protected from an exaggerated hypertensive response (OR 0.45, 95%CI 0.30-0.67). However, using the definition of exercise-induced hypertension that corrects for maximal workload, less fit firefighters had almost twice the risk (OR 1.8, 95%CI 1.3-2.47). Blood pressure change corrected for maximal workload is better correlated with cardiorespiratory fitness. Systolic blood pressure elevation during peak exercise likely represents an adaptive response, whereas elevation out of proportion to the maximal workload may indicate insufficient vasodilation and a maladaptive response. Prospective studies are needed to best define exaggerated blood pressure response to exercise.

Obesity is associated with the future risk of heavy truck crashes among newly recruited commercial drivers

This study estimates the dose-response relationship between body mass index (BMI) and crash risk in operators of heavy commercial motor vehicles. Intake data were collected during the first two weeks of instruction from 744 new truck drivers training for their commercial driver's licenses at a school operated by the cooperating trucking firm. Drivers were then followed prospectively on the job using the firm's operational data for two years, or until employment separation, whichever came first. Multivariate Poisson regression and Cox proportional hazards models were used to estimate the relationship between crash risk and BMI, controlling for demographic characteristics and for variations in the exposure to risks on the road. Results from the Poisson regression, which used cumulative miles driven as an exposure control, indicated that compared to normal BMI (18.5<BMI<25) the risk ratio (RR) for all crashes was significantly higher for drivers in the combined obesity Classes II and III: RR=1.55 (95% CI 1.24-1.94). Similarly, the multivariate Cox proportional hazard model (controlling for miles and job type on a week-by-week basis) showed that crash risk was significantly higher compared to normal BMI for the same combined obesity Classes II and III: RR=1.54 (95% CI 1.13-2.10). The results of this prospective study establish an association between obesity and crash risk and have important implications for driver health and public safety.

Portable diagnostic devices for identifying obstructive sleep apnea among commercial motor vehicle drivers: considerations and unanswered questions

Obstructive sleep apnea (OSA), a syndrome defined by breathing abnormalities during sleep, can lead to fatigue and excessive daytime sleepiness (EDS) with an increased risk of motor vehicle crashes. Identifying commercial motor vehicle operators with unrecognized OSA is a major public health priority. Portable monitors (PMs) are being actively marketed to trucking firms as potentially lower-cost and more accessible alternatives to the reference standard of in-laboratory polysomnography (PSG) in the diagnosis of OSA among commercial motor vehicle operators. Several factors regarding PMs remain uncertain in this unique patient population: their sensitivity and specificity; the cost-benefit ratio of the PMs versus PSG; potential barriers from human factors; and evolving technologic advancement. Human factors that alter test accuracy are a major concern among commercial drivers motivated to gain/maintain employment. Current available data using PMs as a diagnostic tool among CMV operators indicate relatively high data loss and high loss to follow-up. Loss to follow-up has also been an issue using PSG in commercial motor vehicle operators. Furthermore, PM testing and PM results interpretation protocols may have no sleep specialist oversight, and sometimes minimal physician oversight and involvement. Additional studies comparing unattended and unmonitored PMs directly against full in-laboratory PSG are needed to provide evidence for their efficacy among commercial motor vehicle operators.