Healthy Worker Effect Research Articles

Biases in COVID-19 vaccine effectiveness studies using cohort design

Observational studies on COVID-19 vaccine effectiveness (VE) have provided critical real-world data, informing public health policy globally. These studies, primarily using pre-existing data sources, have been indispensable in assessing VE across diverse populations and developing sustainable vaccination strategies. Cohort design is frequently employed in VE research. The rapid implementation of vaccination campaigns during the COVID-19 pandemic introduced differential vaccination influenced by sociodemographic disparities, public policies, perceived risks, health-promoting behaviors, and health status, potentially resulting in biases such as healthy user bias, healthy vaccinee effect, frailty bias, differential depletion of susceptibility bias, and confounding by indication. The overwhelming burden on healthcare systems has escalated the risk of data inaccuracies, leading to outcome misclassifications. Additionally, the extensive array of diagnostic tests used during the pandemic has also contributed to misclassification biases. The urgency to publish quickly may have further influenced these biases or led to their oversight, affecting the validity of the findings. These biases in studies vary considerably depending on the setting, data sources, and analytical methods and are likely more pronounced in low- and middle-income country (LMIC) settings due to inadequate data infrastructure. Addressing and mitigating these biases is essential for accurate VE estimates, guiding public health strategies, and sustaining public trust in vaccination programs. Transparent communication about these biases and rigorous improvement in the design of future observational studies are essential.

Understanding labour exploitation as a social determinant of health in migrant populations – insights from the Danish population-based registers

Abstract Despite recent global events such as the COVID-19 pandemic and the Qatar world cup drawing attention to the significant loss of human lives of labour migrants in precarious working conditions, evidence on the comparative mortality of migrant workers remains sparse and inconsistent. Studying the comparative mortality of migrant workers with local workers is challenging for several reasons. Data on migrants’ employment conditions and health outcomes are often incomplete, and when available captured in separate databases. In addition, there is a need to disentangle the healthy migrant effect from the healthy worker effect, which presents challenges in the selection of reference populations and temporality when studying mortality of migrants. In view of such challenges, Denmark provides an ideal context to study labour migration and mortality. The Danish population-based registers offer linked longitudinal data on migrants’ employment history and mortality outcomes. Denmark’s migrant integration policy also has a history of weaving immigration and labour policies, and migrants in Denmark continue to be prone to labour exploitation in high-risk industries such as construction and agriculture. This presentation shall use Denmark as a case study to compare the mortality outcomes of migrant workers with Danish workers to better understand labour exploitation as a social determinant of health.

Organisational changes and depression: The mediating role of psychosocial work exposures in the SUMER study

BackgroundStudies are lacking on the associations between organisational changes and mental disorders and the underlying mechanisms. The objectives were to explore the associations between organisational changes and depression, measured using a validated instrument, and the mediating role of psychosocial work exposures. MethodsThe study relied on the national representative sample of 25,977 employees of the French SUMER survey. The PHQ-9 instrument was used to measure depression. Weighted robust Poisson regression analyses were performed to explore the associations between organisational changes, psychosocial work exposures, and depression. The method by Karlson, Holm and Breen (KHB) was used to estimate the mediating role (contributions) of psychosocial work exposures in the associations between organisational changes and depression. ResultsThe exposure to any organisational change increased the risk of depression (Prevalence Ratio = 1.85, 95 % CI: 1.61–2.13). All types of organisational changes were found to be risk factors for depression. The risk of depression increased with the number of organisational changes. Psychosocial work exposures contributed to mediating the associations between organisational changes and depression. The exposures with the highest contributions were found to be high psychological demands, low esteem, low job promotion, low job security, workplace bullying, and ethical conflict. Taking all the exposures into account mediated the associations by 47–100 %. LimitationsThe study limitations included the cross-sectional design and a potential healthy worker effect. ConclusionsMore prevention oriented towards work organisation and the psychosocial work environment may help to reduce depression among working populations.

The Healthy User Effect in Pharmacoepidemiology.

The healthy user effect is a well-recognized bias in the field of pharmacoepidemiology and can be expected to overstate the effect of a preventive intervention when comparing long term users or "adherers" to non-users. Similar to the healthy worker effect observed in occupational epidemiology, the healthy user effect can be separated into a healthy initiator effect (baseline confounding) and a healthy adherer effect (selection bias). Restriction approaches and new user designs that implicitly condition on the indication and, similar healthy behaviors or health status can often mitigate the healthy initiator effect (confounding) or healthy adherer effect (selection bias) at the start of a study. Addressing the healthy adherer effect due to continued conditioning on adherence over the duration of a study is more challenging as methods to mitigate it require the ability to predict adherence, which is often difficult using databases common in pharmacoepidemiologic research. Here, we describe the healthy user effect, with supporting examples, and describe study design approaches available to pharmacoepidemiologists to mitigate the potential for bias.

Cancer risk among air transportation industry workers in Korea: a national health registry-based study

BackgroundFlight attendants face various risk factors in their working environments, particularly occupational exposure to cosmic radiation. This study aimed to assess cancer risk among air transportation industry workers, including flight attendants, in Korea by constructing a cohort using national health registry-based data and analyzing cancer incidence risk.MethodsWe used the Korea National Health Insurance Service database from 2002 to 2021 to construct a cohort of 37,011 workers in the air transportation industry. Cancer incidence was defined using the tenth version of the International Classification of Diseases. We calculated the age- and sex-specific standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) by applying the cancer incidence rate of the general population between 2002 and 2019.ResultsApproximately 5% of the cohort developed cancer. Overall, the cancer incidence in the cohort was similar to or lower than that of the general population, with the SIRs for all cancers being lower. However, significantly higher SIRs were observed for nasopharyngeal cancer (SIR, 3.21; 95% CI, 1.71–5.48) and non-Hodgkin lymphoma (SIR, 1.57; 95% CI, 1.02–2.32) in male workers and breast and genital cancer (SIR, 1.51; 95% CI, 1.34–1.70) and thyroid cancer (SIR, 1.25; 95% CI, 1.05–1.47) in female workers.ConclusionsThe lower overall cancer incidence among air transportation industry workers observed in this study could indicate the “healthy worker effect”; however, the incidences of certain cancers were higher than those in the general population. Given that these workers are exposed to multiple occupational and lifestyle-related risk factors, including cosmic radiation, further studies are necessary to determine radiation-induced cancer risk while considering potential confounding factors.

Healthy worker hire and survivor effects in a cohort of medical radiation workers.

The healthy worker effect may distort the association between exposure and health effects in workers. However, few studies have investigated both the healthy worker hire and survival effects simultaneously, and they are limited to mortality studies in male workers. We utilized a data set comprising South Korean diagnostic medical radiation workers registered in the National Dose Registry between 1996 and 2011, and merged it with mortality and cancer incidence data. Standardized mortality ratios (SMRs) and standardized incidence ratios (SIRs) were computed for comparison with the general population. To account for time-varying confounders influenced by prior occupational radiation exposure, we applied g-estimation using structural nested accelerated failure time models and compared the outcomes with those from Weibull regression. A total of 1831 deaths and 3759 first primary cancer cases were identified among 93 918 workers. Both male (SMR = 0.44; 95% CI: 0.42, 0.46) and female workers (SMR = 0.53; 95% CI: 0.46, 0.60) showed lower mortality rates compared with national rates. In the SIR analysis, male workers exhibited reduced risks of solid cancer whereas female workers had increased risks. The g-estimation-derived hazard ratios (HRs) from radiation exposure exceeded those from Weibull regression estimates for all-cause death (HR = 2.55; 95% CI: 1.97, 3.23) and all-cancer incidence (HR = 1.96; 95% CI: 1.52, 2.55) in male workers whereas female workers showed the opposite results. Comprehensive consideration of the healthy worker effect by sex is essential for estimating the unbiased impact of occupational exposure on health outcomes, notably in studies focusing on male mortality.

The risk of infant mortality among the offspring of the workers of radiation hazardous production

Infant mortality is an indicator of healthcare quality and social well-being in a society and could be used as an important parameter in assessing the effects produced by parental occupational exposures on the offspring health. The objective of the study: to analyze the risk of infant mortality in the cohort of the 1st generation offspring of the workers of Mayak Production Association (PA), the first atomic production facility in Russia. Infant mortality and its components were analyzed in a cohort of children (n = 24,780) born in 1949–1973; the main group comprised 14,435 offspring of Mayak PA workers; the comparison group contained 10,345 children of unexposed parents. Incidence and relative risk of early and late neonatal, postneonatal and infant mortality were assessed taking into account the offspring sex, calendar period of birth, nosologies, parental age, categories of accumulated doses of parental preconception occupational exposure. Relative risk was calculated with 95 % confidence interval. A higher incidence of postneonatal and infant mortality as a whole was established among the offspring of unexposed parents. Infectious pathology as a cause of death was registered among the offspring of Mayak PA workers statistically significantly less often than in the comparison group. Infant mortality rate in the main group was lower in parental age categories of 21–25 and 31–35 years as well as among younger fathers. A higher rate of infant mortality in certain categories of accumulated doses of occupational preconception gamma-exposure was caused by the contribution of infectious nosologies. Infant mortality due to malignant neoplasms in the main group requires further epidemiological analysis. A retrospective analysis demonstrated higher rates of infant mortality and of its components among the children of un-exposed parents that could be possibly explained through the “healthy worker effect” and better social well-being of Mayak PA personnel.

Риск младенческой смертности среди потомков работников радиационно-опасного производства

Infant mortality is an indicator of healthcare quality and social well-being in a society and could be used as an important parameter in assessing the effects produced by parental occupational exposures on the offspring health. The objective of the study: to analyze the risk of infant mortality in the cohort of the 1st generation offspring of the workers of Mayak Production Association (PA), the first atomic production facility in Russia. Infant mortality and its components were analyzed in a cohort of children (n = 24,780) born in 1949–1973; the main group comprised 14,435 offspring of Mayak PA workers; the comparison group contained 10,345 children of unexposed parents. Incidence and relative risk of early and late neonatal, postneonatal and infant mortality were assessed taking into account the offspring sex, calendar period of birth, nosologies, parental age, categories of accumulated doses of parental preconception occupational exposure. Relative risk was calculated with 95 % confidence interval. A higher incidence of postneonatal and infant mortality as a whole was established among the offspring of unexposed parents. Infectious pathology as a cause of death was registered among the offspring of Mayak PA workers statistically significantly less often than in the comparison group. Infant mortality rate in the main group was lower in parental age categories of 21–25 and 31–35 years as well as among younger fathers. A higher rate of infant mortality in certain categories of accumulated doses of occupational preconception gamma-exposure was caused by the contribution of infectious nosologies. Infant mortality due to malignant neoplasms in the main group requires further epidemiological analysis. A retrospective analysis demonstrated higher rates of infant mortality and of its components among the children of un-exposed parents that could be possibly explained through the “healthy worker effect” and better social well-being of Mayak PA personnel.

The associations of psychosocial work exposures with suicidal ideation in the national French SUMER study

BackgroundThe literature remains scarce on the work-related risk factors for suicide and suicidal ideation. The objectives were to explore the associations of psychosocial work exposures with suicidal ideation in a nationally representative sample of the working population. MethodsThe study was based on the sample of 25,977 employees (14,682 men and 11,295 women) of the national French 2016–17 SUMER survey. The outcome was suicidal ideation assessed using the PHQ-9 instrument. Psychosocial work exposures included various factors from the job strain and effort-reward imbalance models, and other concepts. Statistical analyses were performed using weighted methods, including weighted logistic regression models. Other occupational exposures and covariates were considered. Gender differences were tested. ResultsThe prevalence of suicidal ideation was 3.5 % without any difference between genders. Psychosocial work exposures were found to be associated with suicidal ideation. The strongest association was observed between workplace bullying and suicidal ideation. Associations were also found between job strain model factors, job insecurity, low esteem, work-family conflict, ethical conflict, teleworking, and low meaning, and suicidal ideation. The associations were in general similar for men and women. LimitationsThe study had a cross-sectional design and no causal interpretation could be done. A reporting bias and a healthy worker effect may be suspected. ConclusionPsychosocial work exposures played a major role in suicidal ideation. More research may be needed to confirm our results, as suicidal ideation is an important warning signal for suicide prevention. More primary prevention towards the psychosocial work environment may be useful to reduce suicidal ideation at the workplace.

Tip of the iceberg: unveiling the impact on back disorders from cumulative physical job exposure and evaluating bias from the healthy worker effect using a nationwide longitudinal cohort study

PurposeLongitudinal studies across various sectors with physically demanding jobs are notably absent in back disorder risk research. This study aimed to investigate the relationship between cumulative physical job exposure (PJE) and hospital-diagnosed back disorders among individuals in Denmark. To assess the healthy worker effect, we compared the cumulative risk estimate with results from a naive cross-sectional model ignoring PJE history.MethodsA nationwide longitudinal cohort study was conducted using Danish registers, encompassing individuals born between 1975 and 1978 and working in 1996. Cumulative PJE was measured with a 10-year look-back period for each year 2006–2017. PJE consisted of lower-body occupational exposures, including the total weight lifted, stand/sit ratio, and the frequency of lifting more than 20 kg per day from a job exposure matrix. Odds ratio for back disorders was estimated for each year and all years combined.ResultsThe results unveiled a significant 31% increase in the risk of hospital-diagnosed back disorders after 4 years of cumulative PJE. The lowest risk (7%) was observed for incident back disorders with 1 year of exposure, suggesting a healthy worker effect. Nevertheless, this risk is still significantly elevated. This cumulative estimate is fourfold the estimate from the 2006 naive cross section model.ConclusionOur study clearly demonstrates an 31% increase in the risk of hospital-diagnosed back disorders with just 4 years of PJE over a 10-year period. Further, we find that cross-sectional studies strongly underestimate the risk of back disorders due to the healthy worker effect.

Effect of colorectal cancer screening on colorectal cancer surgery outcomes: nationwide cohort study.

National colorectal cancer screening commenced in Denmark in 2014. Little is known about the effects of organized colorectal cancer screening on intraoperative and postoperative events. The aim of this nationwide cohort study was to evaluate the difference in intraoperative and postoperative outcomes between patients with screen-detected colorectal cancer and non-screen-detected colorectal cancer within the first 90 days after surgery. National register data were collected for Danish residents diagnosed with colorectal cancer between January 2014 and March 2018. Outcomes for the two cohorts were reported as relative risk or weighted mean difference. Intraoperative outcomes were blood loss, blood transfusion, tumour perforation, and organ lesion. Postoperative outcomes were complications (surgical and non-surgical) and 90-day mortality. Discrete data estimates were calculated from a general linear model. Analyses were adjusted for potential healthy user bias with respect to sex, age, location of the cancer (colon/rectum), and Charlson co-morbidity index. In total, 10 606 patients were included. Compared with patients in the non-screen-detected colorectal cancer group (4497 patients), patients in the screen-detected colorectal cancer group (6109 patients) had reduced intraoperative blood loss (-52 mL, 95% c.i. -67 to -37, P < 0.001), a shorter duration of hospitalization (-2.3 days, 95% c.i. -2.8 to -1.8, P < 0.001), and reduced rates of intraoperative organ lesion (0.76, 95% c.i. 0.59 to 0.99, P = 0.042), surgical complications (0.79, 95% c.i. 0.73 to 0.87, P < 0.001), non-surgical complications (0.68, 95% c.i. 0.60 to 0.78, P < 0.001), and 90-day mortality (0.29, 95% c.i. 0.21 to 0.39, P < 0.001). In comparison with non-screen-detected colorectal cancer, surgery for screen-detected colorectal cancer remains associated with improvement in several intraoperative and early postoperative outcomes after considering healthy user bias.

Correlation between positive airway pressure and medication adherence: the healthy user effect.

Despite the efficacy of positive airway pressure (PAP) for the treatment of obstructive sleep apnea, adherence remains challenging and negatively affects assessments of effectiveness. It is unclear whether low adherence is due to intolerance of PAP or whether this reflects overall adherence with medical therapy. We sought to correlate PAP use with medication adherence to determine whether poor adherence with PAP was specific to this treatment or represented global compliance with medical therapy. A total of 600 consecutive patients with obstructive sleep apnea were treated with PAP. Objective measures of PAP use were correlated with medication adherence. We included all chronically used medications, defined as medications used daily for at least 90 days prior to PAP initiation. Medication use was verified using an electronic health record. PAP adherence ("regular use") was defined as PAP use for ≥ 4 hours/night on ≥ 70% of nights. Medication adherence was defined as > 70% of pills taken as prescribed. Complete records were available for 566 patients; 361 (63.8%) used chronic medications. The cohort was primarily men (90.3%, age 44.6 ± 10.2 years) with moderate obstructive sleep apnea (apnea-hypopnea index, 18.1 ± 13.9 events/h). In patients on chronic medications, PAP was used 55.8% of nights and 37.7% were regular users. Patients who were adherent with medications used PAP more hours/night (5.4 vs 4.6, P < .001) and were more likely to have regular PAP use compared with those nonadherent with medications (P = .04). Adherence with PAP correlated with adherence to chronic medications. Low PAP adherence may reflect an individual's global adherence to medical care. This association may lead to better identification of patients who benefit from targeted therapy to improve overall health care adherence. Lettieri MJ, Warren WA, Walter RJ, Lettieri CJ. Correlation between positive airway pressure and medication adherence: the healthy user effect. J Clin Sleep Med. 2024;20(7):1087-1092.

Correlation between positive airway pressure and medication adherence – the healthy user effect

Correlation between positive airway pressure and medication adherence – the healthy user effect

Estrés y ansiedad en estudiantes de enfermería durante la primera ola de la pandemia de COVID-19.

To compare anxiety and acute stress levels among nursing students who joined the labour market during the first wave of the COVID-19 pandemic and those who did not. A cross-sectional, multicentre descriptive study across three Spanish public universities. A total of 216 nursing students participated in our study. Data collection was carried through an online questionnaire, that included variables on conditions for entering the labour market, the Zung Anxiety Self-Assessment Scale and the Stanford Acute Stress Reaction Questionnaire. We performed univariate and multivariate analyses. Results: Overall, 42.6% (n=92) of the students entered the labour market during the first wave of the COVID-19 pandemic. The global anxiety score was x?=36.31 (SD=5.71) and the stress score was x?=82.39 (SD=30.84). Lower anxiety levels were observed among those who joined the labour market (x?=35.67; SD=5.78) as compared to those who did not (x?=36.73; SD=5.67). Overall 92.4% of the students were acutely stressed. Acute stress was higher among those who did not work (x?=84.35; SD=32.38) and significantly in women. Conclusions: Nursing students were able to cope with stress in situations such as the COVID-19 pandemic. A healthy worker effect could not be ruled out. Stress and anxiety among nursing students should be considered by clinical practice preceptors and at the time students first enter the labour market.

Treatment of patients with screen-detected colorectal cancer is less strenuous: a nationwide cohort study with long-term follow-up

ObjectiveDuring the last two decades, organised colorectal cancer (CRC) screening has been widely implemented. It remains to be established if screen-detected CRC (SD-CRC) is associated with reduced long-term requirements for treatment as compared with patients with non-screen-detected CRC (NSD-CRC). Study design and methodsThis nationwide cohort study evaluated differences in treatment and healthcare contacts from the date of diagnosis to two years after comparing patients with SD-CRC and NSD-CRC. Data were collected from national healthcare registers, including patients aged 50–75 years and diagnosed with CRC between January 1st 2014 and March 31st 2018. Analyses were stratified into UICC stages and adjusted for sex, 5-year age groups, type of cancer (colonic/rectal), and Charlson comorbidity index score to address healthy user bias. ResultsIn total, 12,040 patients were included, 4708 with SD-CRC and 7332 with NSD-CRC. In patients with SD-CRC, the duration of hospitalisation and rate of emergency surgery were reduced by 38 % (relative risk [RR] = 0.62) and 66 % (RR = 0.34), respectively. Moreover, this group was characterised by a 75 % reduction in oncological outpatient visits (RR = 0.35) and a reduced number of treatments with chemotherapy (RR = 0.57) and radiotherapy (RR = 0.50). There were no significant differences between the two populations in the rates of metastasectomy and the number of contacts with primary healthcare providers. ConclusionCompared to patients with NSD-CRC, patients with SD-CRC experience less hospitalisation and treatment within the first two years after diagnosis.

Cancer mortality in workers at risk of occupational exposure to ionizing radiation in a company in the nuclear sector headquarters in São Paulo.

To compare cancer mortality among workers exposed to gamma and X radiation and the general population of the city of São Paulo, as well as that of the subgroup monitored with those not monitored for gamma and X radiation in a work unit with ionizing radiation based in the city of São Paulo. Between 2016 and 2021, a retrospective open cohort study was carried out with workers who were employed from 08/31/1956 to 12/31/2016 based on data collected at the company and in official institutions. Standardized mortality ratios (SMR) were calculated by sex, age and calendar period of cancers grouped according to type, risk factor and organ system in two analyses: in the external analysis, the mortality of the study population was compared with that of the general population of the city of São Paulo; In the internal analysis, the mortality of the monitored subgroup was compared with that of the subgroup not monitored for gamma and X radiation. The external mortality analysis showed SMR=0.224 (95%CI 0.208-0.240) and the healthy worker effect, while the internal mortality analysis showed SMR=0.685 (95%CI 0.618-0.758). This study showed lower cancer mortality among exposed workers when compared to mortality in the general population and the healthy worker effect. Among workers monitored for gamma and X radiation, cancer mortality was lower when compared to those not monitored.

Moderate alcohol consumption on the risk of stroke in the Million Veteran Program

BackgroundThere is inconsistent evidence on the association of moderate alcohol consumption and stroke risk in the general population and is not well studied among U.S. Veterans. Furthermore, it is unclear whether primarily drinking beer, wine, or liquor is associated with a difference in stroke risk.MethodsThe study included 185,323 Million Veteran Program participants who self-reported alcohol consumption on the Lifestyle Survey. Moderate consumption was defined as 1–2 drinks/day and beverage preference of beer, wine or liquor was defined if ≥ 50% of total drinks consumed were from a single type of beverage. Strokes were defined using ICD-9 and ICD-10 codes from the participants’ electronic health record.ResultsThe mean (sd) age of the sample was 64 (13) years and 11% were women. We observed 4,339 (94% ischemic; 6% hemorrhagic) strokes over a median follow-up of 5.2 years. In Cox models adjusted for age, sex, race, education, income, body mass index, smoking, exercise, diet, cholesterol, prevalent diabetes, prevalent hypertension, lipid-lowering medication, antihypertensive medication, and diabetes medication, moderate alcohol consumption (1–2 drinks/day) was associated with a 22% lower risk of total stroke compared with never drinking [Hazards ratio (HR) 95% confidence interval (CI): 0.78 (0.67, 0.92)]. When stratifying by stroke type, we observed a similar protective association with moderate consumption and ischemic stroke [HR (95% CI): 0.76 (0.65, 0.90)], but a non-statistically significant higher risk of hemorrhagic stroke [HR (95% CI): 1.29 (0.64, 2.61)]. We did not observe a difference in ischemic or hemorrhagic stroke risk among those who preferred beer, liquor or wine vs. no beverage preference. When stratifying by prior number of hospital visits (≤ 15, 16–33, 34–64, ≥ 65) as a proxy for health status, we observed attenuation of the protective association with greater number of visits [HR (95% CI): 0.87 (0.63, 1.19) for ≥ 65 visits vs. 0.80 (0.59, 1.08) for ≤ 15 visits].ConclusionsWe observed a lower risk of ischemic stroke, but not hemorrhagic stroke with moderate alcohol consumption and did not observe substantial differences in risk by beverage preference among a sample of U.S. Veterans. Healthy user bias of moderate alcohol consumption may be driving some of the observed protective association.

Mortality, cancer incidence, and disability among professional drivers in Slovenia.

Literature data about all-cause and cause-specific mortality among professional drivers are inconsistent. Most studies report lower all-cause and higher cause-specific mortality. Higher cause-specific mortality is most often the result of malignant and circulatory diseases. The aim of our retrospective cohort study was to get a better insight into the mortality, cancer incidence, and occupational disability of the entire professional driver population in Slovenia (N=8,231) from 1997 to 2016 through standardised mortality ratio (SMR), standardised proportional mortality ratio (SPMR), standardised cancer incidence ratio (SIR), and standardised disability ratio (SDR). Total mortality was significantly lower than that of the general working population (SMR=0.49; 95 % CI=0.44-0.55). When SPMR was calculated, however, the risk of all-cause mortality increased to 1 (SPMR=1.00; 95 % CI=0.89-1.12), of cancer-related mortality to 1.13 (95 % CI=0.94-1.35), and of injury-related mortality to 1.25 (95 % CI=0.97-1.59). Cancer incidence was lower than in the general male working population for all types of cancer (SIR=0.66; 95 % CI=0.59-0.72), lung cancer included (SIR=0.56; 95 % CI=0.41-0.73). Occupational all-cause and cause-specific disability were also lower than in the rest of the working population. Even though all types of cancer and injuries were established among professional drivers in Slovenia, no major risk stand out. However, our findings may have been skewed by the healthy worker effect.

The self-rating of life quality by workers of metal-processing industry

The cross-sectional study of subjective assessment of quality of life of 300 employees of main professions of metalworking industrial production working in harmful labor environment (classes 3.1-3.4) was carried out using validated Russian version of the WHO QOL-BREF questionnaire. The software Statistica 10 was applied for statistical analysis. The statistical processing of study results was performed by calculating arithmetic mean (M), standard deviation (SD) and presented as M±SD. The non-parametric statistical methods were applied to compare two independent samples: the Mann-Whitney U criterion, the Spearman rank correlation coefficient. The data differences and correlations between the data at p<0.05 were considered statistically significant. Based on the results of analysis, satisfaction of employees with quality of life across all domains was established. The quality of life indicators were independent of gender of respondents. With age and experience, decrease of indicators for all domains was established. High indicators for physical health domain and subjective assessment of health status in examined group can be explained from the standpoint of the "healthy worker effect", but concealment of information about true state of health cannot be ruled out. The metal industry workers working in harmful labor conditions are conditionally healthy and active. There is a need for additional research to obtain objective assessment of their health status.

Self-reported Cardiovascular Disease in Career Firefighters With and Without World Trade Center Exposure.

To assess the effect of World Trade Center (WTC) exposure on cardiovascular disease (CVD) in career firefighters. Methods: Firefighters from four US cities completed health questionnaires that provide information about demographics, CVD diagnoses, and CVD risk factors. Firefighters were also compared with respondents of the 2019 National Health Interview Survey. Results: Greater WTC exposure was positively associated with combined coronary artery disease, myocardial infarction, and angina (termed "CAD") when comparing WTC-exposed with non-WTC-exposed firefighters. Compared with the National Health Interview Survey population, firefighters had lower odds of CAD and stroke. Conclusions: An occupationally appropriate comparison is important to mitigate potential bias from the healthy worker effect. While the risk of CVD in WTC-exposed and non-WTC-exposed firefighters was significantly lower than a general US population, we observed an exposure gradient where greater WTC exposure was associated with greater odds of CVD.