Shift and Night Work and All-Cause and Cause-Specific Mortality: Prospective Results From the STRESSJEM Study

The literature remains sparse and inconclusive about the impact of shift and night work on mortality, and still more on specific causes of death. The objectives were to explore the prospective associations between exposure to shift and night work and all-cause and cause-specific mortality. The study was based on a large national representative French prospective cohort of 1,511,456 employees followed up from 1976 to 2002. Exposure to shift and night work relied on a job-exposure matrix, and 3 time-varying measures (current, cumulative, and recency-weighted cumulative exposure) were constructed. Mortality and causes of death were provided by the national registry, and all-cause, cardiovascular, cancer and preventable mortality, and suicide were studied. Cox proportional hazards models were performed to study the associations between shift and night work and mortality. During follow-up, 22,105 deaths occurred for all-cause mortality. In the study of mortality until the end of last job during follow-up, shift and/or night work were associated with all-cause, cardiovascular, cancer and preventable mortality, and suicide (except night without shift work with cancer mortality and suicide) among men. Shift work (especially shift without night work) was associated with all-cause, cancer and preventable mortality among women. The results were similar for current, cumulative, and recency-weighted cumulative exposure. Associations were found for more detailed causes of death: cerebrovascular diseases for both genders, ischemic heart diseases, respiratory cancers, smoking-related mortality, and external causes of death among men, and breast cancer among women. In the study of mortality until the end of follow-up, some additional associations were found among women between night work and all-cause and preventable mortality, and suicide, suggesting long-term or delayed exposure effects. The study may, however, be underpowered to detect all the exposure-outcome associations, especially among women. More research and prevention are needed to reduce mortality among shift and night workers.

Psychosocial Work Factors of the Job Strain Model and All-Cause Mortality: The STRESSJEM Prospective Cohort Study

OBJECTIVE

The objectives were to examine the prospective associations between psychosocial work factors of the job strain model and all-cause mortality in a national representative cohort of French employees using various measures of time-varying exposure.

METHODS

The study was based on a sample of 798,547 men and 697,785 women for which data on job history from 1976 to 2002 were linked to mortality data from the national death registry. Psychosocial work factors from the validated job strain model questionnaire were imputed using a job-exposure matrix. Three time-varying measures of exposure were explored: current, cumulative, and recency-weighted cumulative exposure. Cox proportional hazards models were performed to study the associations between psychosocial work factors and mortality.

RESULTS

Within the 1976-2002 period, 88,521 deaths occurred among men and 28,921 among women. Low decision latitude, low social support, job strain, isostrain, high strain, and passive job were found to be risk factors for mortality. The model using current exposure was the best relative-quality model. The associations of current exposure to job strain and mortality were found to have hazard ratios of 1.30 (95% confidence interval [CI] = 1.24-1.36) among men and 1.15 (95% CI = 1.06-1.25) among women. The population fractions of mortality attributable to job strain were 5.64% (95% CI = 4.56%-6.71%) among men and 4.13% (95% CI = 1.69%-6.71%) among women.

CONCLUSIONS

This study supports the role of the psychosocial work factors of the job strain model on all-cause mortality. Preventive intervention to improve the psychosocial work environment may help to prevent mortality in working populations.

Psychosocial work exposures of the job strain model and cardiovascular mortality in France: results from the STRESSJEM prospective study

Objectives:

The study aims to explore the prospective associations of the psychosocial work exposures of the job strain model with cardiovascular mortality, including mortality for ischemic heart diseases (IHD) and stroke, using various time-varying exposure measures in the French working population of employees.

Methods:

The study was based on a cohort of 798 547 men and 697 785 women for which job history data from 1976 to 2002 were linked to mortality data and causes of death from the national death registry. Psychosocial work exposures from the validated job strain model questionnaire were assessed using a job-exposure matrix (JEM). Three time-varying measures of exposure were studied: current, cumulative, and recency-weighted cumulative exposure. Cox proportional hazards models were used to examine the associations between psychosocial work exposures and cardiovascular mortality.

Results:

Within the 1976–2002 period, there were 19 264 cardiovascular deaths among men and 6181 among women. Low decision latitude, low social support, job strain, iso-strain, passive job, and high strain were associated with cardiovascular mortality. Most of these associations were also observed for IHD and stroke mortality. The comparison between the different exposure measures suggested that current exposure may be more important than cumulative (or past) exposure. The population fractions of cardiovascular mortality attributable to job strain were 5.64% for men and 6.44% for women.

Conclusions:

Psychosocial work exposures of the job strain model may play a role in cardiovascular mortality. The estimated burden of cardiovascular mortality associated with these exposures underlines the need for preventive policies oriented toward the psychosocial work environment.

Carpal Tunnel Syndrome Among Male French Farmers and Agricultural Workers: Is It Only Associated With Physical Exposure?

Background

Exploratory study to investigate whether co-exposure to physical wrist stressors and chemicals is associated with carpal tunnel syndrome (CTS) in French male farmers and agricultural workers.

Methods

Cross-sectional study of 711 men aged 30–65 years and working as either farmers or agricultural workers in 2009–2010 within a cohort covered by the French Agricultural Workers' and Farmers' Mutual Benefit Fund. CTS and exposure to physical wrist stressors and chemicals were assessed using a self-administered questionnaire. Associations between CTS and personal/medical factors, exposure to physical wrist stressors, exposure to chemicals, and co-exposure to physical wrist stressors and chemicals were studied using multivariate logistic regression models.

Results

Forty-four men {5.6% [95% confidence interval (CI) 4.0–7.7]} reported that they had suffered from unilateral/bilateral CTS during the last 12 months. CTS was associated with age, current smoking [odds ratio (OR) = 2.1 (1.0–4.5)], and exposure to physical wrist stressors [OR = 2.6 (1.1–5.9)]. An association was found between CTS and co-exposure to physical wrist stressors and chemicals [OR = 3.3 (0.8–14.3), p = 0.044] in comparison with the no-exposure group.

Conclusions

This exploratory study shows an association of CTS with exposure to biomechanical wrist stressors in male farmers and agricultural workers and suggests an association of CTS with co-exposure to physical wrist stressors and chemicals. Owing to the limitations of the study, this result must be confirmed by a prospective study with objective assessments of the outcome and exposure before drawing conclusions on the possible synergistic effects of mechanical stressors and chemicals on the impairment of the median nerve.

Prospective associations of psychosocial work exposures with mortality in France: STRESSJEM study protocol

INTRODUCTION

Although evidence has been provided on the associations between psychosocial work exposures and morbidity outcomes in the literature, knowledge appears much more sparse on mortality outcomes. The objective of STRESSJEM is to explore the prospective associations between psychosocial work exposures and mortality outcomes among the national French working population. In this paper, we describe the study protocol, study population, data sources, method for exposure assessment, data analysis and future plans.

METHODS AND ANALYSIS

Data sources will include: the data from the national SUMER survey from DARES on the evaluation of psychosocial work exposures and the data from the COSMOP programme from Santé publique France linking job history (DADS data from INSEE) and mortality according to causes of death (data from the national death registry, INSERM-CépiDc). A sample of 1 511 456 individuals will form the studied prospective cohort for which data are available on both job history and mortality over the period 1976-2002. Psychosocial work exposures will be imputed via a job-exposure matrix using three job title variables that are available in both the SUMER and COSMOP data sets. Our objectives will be to study the associations between various psychosocial work exposures and mortality outcomes. Psychosocial work exposures will include the job strain model factors as well as other psychosocial work factors. Various measures of exposure over time will be used. All-cause and cause-specific mortality will be studied.

ETHICS AND DISSEMINATION

Both the SUMER survey and the COSMOP programme have been approved by French ethics committees. Dissemination of the study results will include a series of international peer-reviewed papers and at least one paper in French. The results will be presented in national and international conferences. This project will offer a unique opportunity to explore mortality outcomes in association with psychosocial work exposures in a large national representative sample of the working population.

A two-phase sampling survey for nonresponse and its paradata to correct nonresponse bias in a health surveillance survey

BACKGROUND

The decline in participation rates in surveys, including epidemiological surveillance surveys, has become a real concern since it may increase nonresponse bias. The aim of this study is to estimate the contribution of a complementary survey among a subsample of nonrespondents, and the additional contribution of paradata in correcting for nonresponse bias in an occupational health surveillance survey.

METHODS

In 2010, 10,000 workers were randomly selected and sent a postal questionnaire. Sociodemographic data were available for the whole sample. After data collection of the questionnaires, a complementary survey among a random subsample of 500 nonrespondents was performed using a questionnaire administered by an interviewer. Paradata were collected for the complete subsample of the complementary survey. Nonresponse bias in the initial sample and in the combined samples were assessed using variables from administrative databases available for the whole sample, not subject to differential measurement errors. Corrected prevalences by reweighting technique were estimated by first using the initial survey alone and then the initial and complementary surveys combined, under several assumptions regarding the missing data process. Results were compared by computing relative errors.

RESULTS

The response rates of the initial and complementary surveys were 23.6% and 62.6%, respectively. For the initial and the combined surveys, the relative errors decreased after correction for nonresponse on sociodemographic variables. For the combined surveys without paradata, relative errors decreased compared with the initial survey. The contribution of the paradata was weak.

CONCLUSION

When a complex descriptive survey has a low response rate, a short complementary survey among nonrespondents with a protocol which aims to maximize the response rates, is useful. The contribution of sociodemographic variables in correcting for nonresponse bias is important whereas the additional contribution of paradata in correcting for nonresponse bias is questionable.

Socioprofessional trajectories and mortality in France, 1976-2002: a longitudinal follow-up of administrative data

BACKGROUND

Occupying a low socioeconomic position is associated with increased mortality risk. To disentangle this association, previous studies considered various dimensions of socioeconomic trajectories across the life course. However, they used a limited number of stages. We simultaneously examined various dimensions of the whole professional trajectory and its association with mortality.

METHODS

We used a large sample (337,706 men and 275,378 women) of the data obtained by linking individuals' annual occupation (collected in 1976-2002 from a representative panel of the French salaried population in the semipublic and private sectors) with causes of death obtained from registries. All-cause and cause-specific HRs were estimated using Cox's regression models adjusted for the occupational class at the beginning of the follow-up, the current occupational class, the transition rates between occupational categories and the duration of time spent in occupational categories.

RESULTS

An increase in the time spent in the clerk class increased men and women's cardiovascular mortality risk compared with that in the upper class (HRs=1.59 (1.14 to 2.20) and 2.65 (1.14 to 6.13) for 10 years increase, respectively, for men and women). Men with a high rate of transitions had about a 1.2-fold increased risk of all-cause and external-cause mortality compared with those without transitions during their professional life. This association was also observed for women's all-cause mortality.

CONCLUSIONS

Strong associations between professional trajectories and mortality from different causes of death were found. Long exposure to lower socioeconomic conditions was associated with increased mortality risk from various causes of death. The results also suggest gradual associations between transition rates and mortality.

Psychotropic drug use in a cohort of workers 4 years after an industrial disaster in France

Two years after the 2001 Toulouse industrial disaster, a longitudinal study was set up to evaluate the impact of the disaster. The current substudy examines the medium-term impact (5 years) the incident had on the mental health of 3,004 participants. As part of the monitoring, data relating to the psychotropic drug use of 2,494 participants were collected from administrative databases 4 years after the disaster. Use of psychotropics was higher among women for anxiolytics (10.4% for men and 15.0% for women), hypnotics (10.5% and 17.0%), and antidepressants (7.6% and 11.2%). Exposure to the disaster, especially proximity to the exposure, was significantly associated with the use of antidepressants in men, OR = 3.22, 95% CI[1.57, 6.61]. This was also the case for other exposure factors (saw dead or injury, injured, home damage, death or injury loved one, psychological disorders, exposure toxic fumes): range of OR 1.75 to 2.52 in men, 1.48 to 1.62 in women. In conclusion, this study highlights the medium-term psychological impact of an industrial disaster on psychotropic drug use and the potential for using medical records data as a means for tracking postdisaster mental health.

Personality and the risk of cancer: a 16-year follow-up study of the GAZEL cohort

OBJECTIVE

Large-scale prospective studies do not support an association between neuroticism and extroversion with cancer incidence. However, research on other personality constructs is inconclusive. This longitudinal study examined the associations between four personality measures, Type 1, "suppressed emotional expression"; Type 5, "rational/antiemotional"; hostility; and Type A with cancer incidence.

METHODS

Personality measures were available for 13,768 members in the GAZEL cohort study (baseline assessment in 1993). Follow-up for diagnoses of primary cancers was obtained from January 1, 1994 to December 31, 2009. Associations between personality and cancer incidence were evaluated using Cox proportional hazards analyses and adjusted for potential confounders.

RESULTS

During a median follow-up of 16.0 years (range, 9 days-16 years), 1139 participants were diagnosed as having a primary cancer. The mean duration between baseline and cancer diagnosis was 9.3 years. Type 1 personality was associated with a decreased risk of breast cancer (hazard ratio per standard deviation = 0.81, 95% confidence interval = 0.68-0.97, p = .02). Type 5 personality was not associated with prostate, breast, colorectal, or smoking-related cancers, but was associated with other cancers (hazard ratio per standard deviation = 1.17, 95% confidence interval = 1.04-1.31, p = .01). Hostility was associated with an increased risk of smoking-related cancers, which was explained by smoking habits, and Type A was not associated with any of the cancer endpoints.

CONCLUSIONS

Several personality measures were prospectively associated with the incidence of selected cancers. These links may warrant further epidemiological studies and investigations about potential biobehavioral mechanisms.

A 26-year cohort mortality study of French construction workers aged 20 to 64 years

OBJECTIVE

The purpose of this report was to study the cause-specific mortality of French workers in the construction industry.

METHODS

From a cohort of 12,788 male workers, standardized mortality ratios (SMRs) and 95% confidence intervals (CI) were calculated for the years between 1974 and 1999 for workers aged 20 to 64 years.

RESULTS

All-cause mortality was significantly increased (SMR=111, CI=106-206). Excess mortality was found for cancers (SMR=125, CI=117-134), especially for the oral cavity and pharynx (SMR=134, CI=108-163), digestive (SMR=120, CI=104-137) and respiratory (SMR=143, CI=128-159) systems; cerebrovascular disease (SMR=130, CI=106-158); diseases of the digestive system (SMR=130, CI=113-149), and accidental falls (SMR=158, CI=105-125). Excess risks were limited to blue-collar workers.

CONCLUSIONS

Despite a probable role of lifestyle and potential limitations of the study, elevated mortality was observed for several causes possibly related to occupational factors.

[Comparison of the French DRG based information system (PMSI) with the National Mesothelioma Surveillance Program database]

BACKGROUND

One of the main purposes of the French National Mesothelioma Surveillance Program is to estimate and follow the national incidence of pleural mesothelioma. We wanted to study the contribution of the French hospital national database as a valid source of mesothelioma incident cases.

METHODS

From the 1998 and 1999 hospital national database, medical records with a diagnosis code of mesothelioma or pleural cancer where selected among patients who resided in one of the 17 administrative divisions covered by the National Mesothelioma Surveillance Program in 1998. From these records, 506 patients in 1998 and 474 patients in 1999 where identified and matched with the National Mesothelioma Surveillance Program cases over the same period using indirect criteria of identification (sex, age, place of residence). Medical records of cases unknown by the National Mesothelioma Surveillance Program where consulted in one of the administrative divisions.

RESULTS

Only two-thirds of the registered cases of the National Mesothelioma Surveillance Program could be matched with a patient identified in the hospital national database with a diagnosis of mesothelioma registered during the same year. Consultation of the medical records showed that 1) certified cases registered in the National Mesothelioma Surveillance Program where often (83%) found in the hospital national database with a code of mesothelioma but 10 to 15% of the patients with a code of mesothelioma in the national hospital databases had a different diagnosis according to their medical records; 2) 65% of the patients with a code of mesothelioma in the national hospital databases that where unknown from the National Mesothelioma Surveillance Program in 1998 and 55% in 1999 where prevalent cases; 3) 3 suspected cases had not been reported to the National Mesothelioma Surveillance Program.

CONCLUSION

Because of lack of diagnosis certification, mistakes in encoding diagnosis and the fact that incident and prevalent cases cannot be distinguished in the hospital national database make it impossible to estimate the mesothelioma incidence solely from this source of data. However, the hospital claim databases constitute a complementary source of information for the active search of incident cases performed by the National Mesothelioma Surveillance Program.

Social inequalities and cancer mortality in France, 1975-1990

OBJECTIVE

to investigate social inequalities in cancer mortality from 1975 through 1990 among men and women in France.

METHODS

A sample, that included census data for approximately 1% of the French population, has been followed for mortality from 1975 to 1990. Causes of death were obtained through a record-linkage with the French national cause-of-death file. The analysis was restricted to those aged 35:59 in 1975 and included 61,876 men and 65,291 women. Occupational class, coded according to the social class scheme of Erikson, Goldthorpe and Portecarero in 7 categories, and educational level (in 4 categories) in 1975 have been studied. The analysis has been conducted for 15 cancer sites among men and 13 among women. Analysis used a Cox proportional hazards model.

RESULTS

For educational level, inequalities among men were more pronounced for cancers of the pharynx Relative Risk (RR) lowest versus highest educational level=9.2, 95% Confidence Interval (CI) 2.9-29.1, larynx (RR=6.2, CI=3.0:12.6), oral cavity (RR=2.7, CI=1.3-5.3), lung (RR=3.5, CI=2.5-4.8), esophagus (RR=3.1, CI=1.9-5.2), stomach (RR=2.5, CI=1.2-5.3) and rectum (RR=3.4, CI=1.2-9.6). No association between educational level and cancer mortality was observed for cancers of either the colon or lymphatic and hematopoietic tissue. Social inequalities were less pronounced among women but nevertheless observed for cancer of the uterus (RR=1.9, CI=1.0-3.6), stomach (RR=4.1, CI=1.0-17.1) and lung (RR=1.6, CI=0.7-3.7). No associations were found for mortality from breast or ovarian cancers. Results were similar when socioeconomic status was measured by occupational class.

CONCLUSION

The analysis showed substantial inequalities in cancer mortality in France, with large differences according to cancer site.

Variation in breast cancer risk of heterozygotes for ataxia-telangiectasia according to environmental factors

Ataxia-telangiectasia (AT) is a rare autosomal recessive disorder, characterized by progressive neuronal degeneration, immunological deficiency, radio-sensitivity and an increased risk of cancer. Although several studies have confirmed that AT heterozygosis increases the risk of breast cancer (BC), we do not know how exogenous factors affect this risk. We performed an epidemiological study on the cancer risks associated with AT heterozygosis in France and explored the variation in BC risk according to environmental factors, such as reproductive factors and exposure to ionizing radiation. Information on the amount of ionizing radiation received by an individual in their lifetime and on their reproductive life was collected from the living relatives of 34 AT children (175 female relatives). Consistent with previous reports and with our previous estimate on the entire retrospective cohort, we found that the risk of developing BC is 3.6-fold higher among ATM heterozygous women. An increased risk was associated with an early age at menarche, a late age at first childbirth, nulliparity, premenopausal status and increasing periods of breast cell mitotic activity (BCMA) prior to the first childbirth. Age at menarche, age at 1st childbirth and BCMA seemed to have a stronger effect in ATM heterozygotes than in non-ATM heterozygotes. However, the tests were not all statistically significant (only age at 1st childbirth). Surprisingly, the risk of BC decreased when the chest or breasts were irradiated. It is difficult to interpret the data because of the small sample size, but further investigations should provide a biological explanation for the variation in BC risk associated with exogenous factors according to ATM heterozygosis status.

Fluid consumption and the risk of bladder cancer: results of a multicenter case-control study

A number of studies suggest a relation between fluid consumption and the risk of bladder cancer but results are contradictory. Different theories involving the quantity or the type of fluid consumed have been put forward to explain these relations but mechanisms remain unclear. We conducted a multicenter case-control study in several hospitals in France including 765 cases and 765 matched controls. Information collected by face-to-face interview included quantity and type of beverages consumed from the age of 18 until age at diagnosis, as well as smoking habits. Among men, we observed a slight non-significant increased risk of bladder cancer associated with total fluid intake, irrespectively of tobacco use. This was essentially due to intake of non-alcoholic drinks, coffee and bottled juice or water. Relative risks greater than 1 were observed in relation with coffee consumption. On the other hand, alcohol consumption, especially wine, was associated with relative risks less than unity. No relation could be identified between bladder cancer risk and fluid consumption among women. Our results do not support an association between total fluid consumption and bladder cancer risk. The role of the different types of fluid consumed, confounding factors and bias in the present analysis are discussed.

Cancer risk in heterozygotes for ataxia-telangiectasia

Epidemiological studies have suggested that ataxia-telangiectasia (AT) heterozygotes have a predisposition to cancer, especially breast cancer in women. Now, haplotyping can identify heterozygotes for AT mutation (ATM) in AT families, allowing the risk of cancer associated with ATM heterozygosity status to be better assessed. We report a family study of AT patients, in which we estimated the risk of cancer according to ATM heterozygosity status. We analyzed demographic characteristics and occurrence of cancer in 1,423 relatives of AT patients. Haplotyping was performed in living relatives. The probability of being heterozygotes for ATM was calculated for deceased relatives. The risk of developing cancer was estimated in the cohort of relatives, and expected numbers of cancer cases were calculated from French age period-specific incidence rates. The number of cancers at all sites in the total population of relatives was not higher than expected. However, significant heterogeneity was found according to ATM heterozygosity status. This is mainly due to the increased risk of breast cancer previously observed in obligate heterozygotes. In obligate heterozygotes, relative risk (RR) was non-significantly increased for thyroid cancer, leukemia and liver cancer. Risks of ovarian, lung, pancreatic, kidney, stomach and colorectal cancers were non-significantly increased in the group with 0.5 probability of being heterozygotes. The RR was not significantly increased for any site of cancer, except for breast. Therefore, there is no evidence that specific screening of relatives of AT patients would be justified at particular sites other than the breast. However, the amplitude of the risk of breast cancer estimated in heterozygous women does not appear to justify a separate screening program from that already available to women with a first-degree relative affected by breast cancer.