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2.  Persistent asthma, co-morbid conditions and the risk of work disability: a prospective cohort study 
Allergy  2011;66(12):1598-1603.
Backround
This study examined whether asthma alone or together with chronic co-morbidity is associated with increased risk of long-term work disability.
Methods
We examined data from 2,332 asthmatic and 66,354 non-asthmatic public sector employees in Finland who responded to a survey between 1997 and 2004. Respondents were coded as persistent asthmatics based on the special reimbursement for continuous asthma medication by the Social Insurance Institution. Data on long-term work disability (sickness absences or disability pensions >90 days) were obtained from national registers. The risk of work disability was examined by Cox proportional hazard models adjusted for age, gender, socioeconomic status, type of employment contract and type of employer.
Results
Asthma increased the risk of all-cause long-term work disability, hazard ratio (HR) 1.8 (95 % CI 1.62–2.09) compared to controls (no asthma). Asthma and one other chronic co-morbidity increased the risk for long-term all-cause work disability with HR 2.2 (95% CI 1.78–2.83). Asthma together with two or more other chronic conditions increased the risk with HR 4.5 (95% CI 2.98–6.78). Asthma and depression increased the risk with HR 3.6 and the risk was especially high for permanent work-disability (HR 6.8). Among those with asthma there were more women, obesity (BMI ≥30), ex-smokers and lower-grade non-manual workers.
Conclusions
Asthma is associated with increased risk of long-term all-cause work disability. The risk increases further with chronic co-morbidities, and is especially high in patients with asthma and depression.
doi:10.1111/j.1398-9995.2011.02729.x
PMCID: PMC3203316  PMID: 21958351
Asthma; co-morbidity; sickness absence; work disability
3.  Job Strain as a Risk Factor for Leisure-Time Physical Inactivity: An Individual-Participant Meta-Analysis of Up to 170,000 Men and Women 
American Journal of Epidemiology  2012;176(12):1078-1089.
Unfavorable work characteristics, such as low job control and too high or too low job demands, have been suggested to increase the likelihood of physical inactivity during leisure time, but this has not been verified in large-scale studies. The authors combined individual-level data from 14 European cohort studies (baseline years from 1985–1988 to 2006–2008) to examine the association between unfavorable work characteristics and leisure-time physical inactivity in a total of 170,162 employees (50% women; mean age, 43.5 years). Of these employees, 56,735 were reexamined after 2–9 years. In cross-sectional analyses, the odds for physical inactivity were 26% higher (odds ratio = 1.26, 95% confidence interval: 1.15, 1.38) for employees with high-strain jobs (low control/high demands) and 21% higher (odds ratio = 1.21, 95% confidence interval: 1.11, 1.31) for those with passive jobs (low control/low demands) compared with employees in low-strain jobs (high control/low demands). In prospective analyses restricted to physically active participants, the odds of becoming physically inactive during follow-up were 21% and 20% higher for those with high-strain (odds ratio = 1.21, 95% confidence interval: 1.11, 1.32) and passive (odds ratio = 1.20, 95% confidence interval: 1.11, 1.30) jobs at baseline. These data suggest that unfavorable work characteristics may have a spillover effect on leisure-time physical activity.
doi:10.1093/aje/kws336
PMCID: PMC3521479  PMID: 23144364
cohort studies; exercise; physical activity; psychosocial factors; working population
4.  Childhood adversities and adult-onset asthma: a cohort study 
BMJ Open  2012;2(5):e001625.
Objectives
Childhood adversities may be important determinants of later illnesses and poor health behaviour. However, large-scale prospective studies on the associations between childhood adversities and the onset of asthma in adulthood are lacking.
Design
Prospective cohort study with 7-year follow-up.
Setting
Nationally representative study. Data were collected from the Health and Social Support (HeSSup) survey and national registers.
Participants
The participants represent the Finnish population from the following age groups: 20–24, 30–34, 40–44, and 50–54 years at baseline in 1998 (24 057 survey participants formed the final cohort of this study). The occurrence of childhood adversities was assessed at baseline with a six-item survey scale. The analyses were adjusted for sociodemographic characteristics, behavioural health risks and common mental disorders.
Primary and secondary outcomes
The survey data were linked to data from national health registers on incident asthma during a 7-year follow-up to define new-onset asthma cases with verified diagnoses.
Results
A total of 12 126 (59%) participants reported that they encountered a childhood adversity. Of them 3677 (18% of all) endured three to six adversities. During a follow-up of 7 years, 593 (2.9%) participants were diagnosed with incident asthma. Those who reported three or more childhood adversities had a 1.6-fold (95% CI 1.31 to 2.01) greater risk of asthma compared to those without childhood adversities. This hazard attenuated but remained statistically significant after adjustment for conventional risk factors (HR 1.33; 95% CI 1.06 to 1.67).
Conclusions
Adults who report having encountered adversities in childhood may have an increased risk of developing asthma.
doi:10.1136/bmjopen-2012-001625
PMCID: PMC3488721  PMID: 23069774
Psychiatry; Epidemiology
5.  Differences in the association between sickness absence and long-term sub-optimal health by occupational position: a 14-year follow-up in the GAZEL cohort 
Objectives
Although sickness absence is a strong predictor of health, little work has examined whether this association varies by occupational position. The aim of this study was to investigate overall and diagnosis-specific sickness absence as a predictor of future long-term sub-optimal health by occupational position.
Methods
Prospective occupational cohort study; 15,320 employees (73% men) aged 37–51. Sickness absences (1990–1992), including 13 diagnostic categories, were examined by occupational position, based on employment grade, in relation to self-rated health measured annually 1993–2006.
Results
60% of employees in higher grade and 22% in lower grade occupations had no sickness absence. Conversely, 40% of employees in lower grade and 9.5% in higher grade occupations had over 30 sick-leave days. Repeated-measures logistic regression analyses adjusted for age, sex, and chronic disease showed employees with over 30 days absence, compared to those with no absence, had approximately double the risk of suboptimal health over the 14-year follow-up in all occupational positions. However, 1–30 days sick-leave was associated with greater odds of suboptimal health in the high; odds ratio 1.48, 95% confidence intervals (1.27–1.72) and intermediate 1.29 (1.15–1.45), but not lower grade occupations 1.06 (0.82–1.38). Differences by occupational position in the association between sickness absence in 13 specific diagnostic categories and sub-optimal health over the ensuing 14 years were limited to stronger associations observed with cancer and mental disorders in the higher grades.
Conclusions
The association between sickness absence of over 30 days a year and future long-term self-rated health appears to differ little by occupational position.
doi:10.1136/oem.2010.060210
PMCID: PMC3186885  PMID: 21242277
Sickness absence; sick leave; self-rated health; longitudinal; multi-level; occupational position
6.  Associations between Nighttime Traffic Noise and Sleep: The Finnish Public Sector Study 
Environmental Health Perspectives  2012;120(10):1391-1396.
Background: Associations between traffic noise and sleep problems have been detected in experimental studies, but population-level evidence is scarce.
Objectives: We studied the relationship between the levels of nighttime traffic noise and sleep disturbances and identified vulnerable population groups.
Methods: Noise levels of nighttime–outdoor traffic were modeled based on the traffic intensities in the cities of Helsinki and Vantaa, Finland. In these cities, 7,019 public sector employees (81% women) responded to postal surveys on sleep and health. We linked modeled outdoor noise levels to the residences of the employees who responded to the postal survey. We used logistic regression models to estimate associations of noise levels with subjectively assessed duration of sleep and symptoms of insomnia (i.e., difficulties falling asleep, waking up frequently during the night, waking up too early in the morning, nonrestorative sleep). We also used stratified models to investigate the possibility of vulnerable subgroups.
Results: For the total study population, exposure to levels of nighttime–outside (Lnight, outside) traffic noise > 55 dB was associated with any insomnia symptom ≥ 2 nights per week [odds ratio (OR) = 1.32; 95% confidence interval (CI): 1.05, 1.65]. Among participants with higher trait anxiety scores, which we hypothesized were a proxy for noise sensitivity, the ORs for any insomnia symptom at exposures to Lnight, outside traffic noises 50.1–55 dB and > 55 dB versus ≤ 45 dB were 1.34 (95% CI: 1.00, 1.80) and 1.61 (95% CI: 1.07, 2.42), respectively.
Conclusions: Nighttime traffic noise levels > 50 dB Lnight, outside was associated with insomnia symptoms among persons with higher scores for trait anxiety. For the total study population, Lnight, outside > 55 dB was positively associated with any symptoms.
doi:10.1289/ehp.1205026
PMCID: PMC3491945  PMID: 22871637
cohort study; epidemiology; sleep disturbance; traffic noise
7.  Job strain as a risk factor for coronary heart disease: a collaborative meta-analysis of individual participant data 
Lancet  2012;380(9852):1491-1497.
Summary
Background
Published work assessing psychosocial stress (job strain) as a risk factor for coronary heart disease is inconsistent and subject to publication bias and reverse causation bias. We analysed the relation between job strain and coronary heart disease with a meta-analysis of published and unpublished studies.
Methods
We used individual records from 13 European cohort studies (1985–2006) of men and women without coronary heart disease who were employed at time of baseline assessment. We measured job strain with questions from validated job-content and demand-control questionnaires. We extracted data in two stages such that acquisition and harmonisation of job strain measure and covariables occurred before linkage to records for coronary heart disease. We defined incident coronary heart disease as the first non-fatal myocardial infarction or coronary death.
Findings
30 214 (15%) of 197 473 participants reported job strain. In 1·49 million person-years at risk (mean follow-up 7·5 years [SD 1·7]), we recorded 2358 events of incident coronary heart disease. After adjustment for sex and age, the hazard ratio for job strain versus no job strain was 1·23 (95% CI 1·10–1·37). This effect estimate was higher in published (1·43, 1·15–1·77) than unpublished (1·16, 1·02–1·32) studies. Hazard ratios were likewise raised in analyses addressing reverse causality by exclusion of events of coronary heart disease that occurred in the first 3 years (1·31, 1·15–1·48) and 5 years (1·30, 1·13–1·50) of follow-up. We noted an association between job strain and coronary heart disease for sex, age groups, socioeconomic strata, and region, and after adjustments for socioeconomic status, and lifestyle and conventional risk factors. The population attributable risk for job strain was 3·4%.
Interpretation
Our findings suggest that prevention of workplace stress might decrease disease incidence; however, this strategy would have a much smaller effect than would tackling of standard risk factors, such as smoking.
Funding
Finnish Work Environment Fund, the Academy of Finland, the Swedish Research Council for Working Life and Social Research, the German Social Accident Insurance, the Danish National Research Centre for the Working Environment, the BUPA Foundation, the Ministry of Social Affairs and Employment, the Medical Research Council, the Wellcome Trust, and the US National Institutes of Health.
doi:10.1016/S0140-6736(12)60994-5
PMCID: PMC3486012  PMID: 22981903
8.  Differences in the association between sickness absence and long-term sub-optimal health by occupational position: a 14-year follow-up in the GAZEL cohort 
Objectives
Although sickness absence is a strong predictor of health, little work has examined whether this association varies by occupational position. The aim of this study was to investigate overall and diagnosis-specific sickness absence as a predictor of future long-term sub-optimal health by occupational position.
Methods
Prospective occupational cohort study; 15,320 employees (73% men) aged 37–51. Sickness absences (1990–1992), including 13 diagnostic categories, were examined by occupational position, in relation to self-rated health measured annually 1993–2006.
Results
60% of employees in higher occupational position and 22% in lower position had no sickness absence. Conversely, 9.5% of employees in higher position and 40% in lower occupational position had over 30 sick-leave days. Repeated-measures logistic regression analyses adjusted for age, sex, and chronic disease showed employees with over 30 days absence, compared to those with no absence, had approximately double the risk of suboptimal health over the 14-year follow-up in all occupational positions. However, 1–30 days sick-leave was associated with greater odds of suboptimal health in the high; odds ratio 1.48, 95% confidence intervals (1.27–1.72) and intermediate 1.29 (1.15–1.45), but not lower occupational positions 1.06 (0.82–1.38). Differences by occupational position in the association between sickness absence in 13 specific diagnostic categories and sub-optimal health over the ensuing 14 years were limited to stronger associations observed with cancer and mental disorders in the higher occupational positions.
Conclusions
The association between sickness absence of over 30 days a year and future long-term self-rated health appears to differ little by occupational position.
doi:10.1136/oem.2010.060210
PMCID: PMC3186885  PMID: 21242277
Adult; Female; Follow-Up Studies; France; epidemiology; Health Status; Humans; Male; Middle Aged; Occupational Diseases; epidemiology; Occupational Health; statistics & numerical data; Occupations; Prospective Studies; Risk Factors; Sick Leave; statistics & numerical data; Social Class; Sickness absence; sick leave; health; longitudinal; multi-level; occupational position
9.  Environmental Stress Affects DNA Methylation of a CpG Rich Promoter Region of Serotonin Transporter Gene in a Nurse Cohort 
PLoS ONE  2012;7(9):e45813.
Background
Shift-working nurses are exposed to a stressful work environment, which puts them at an increased risk for burnout and depression. We explored the effect of environmental stress on serotonin transporter gene (SLC6A4) promoter methylation among nurses from high and low work stress environments.
Methodology
Using bisulfite sequencing, we investigated the methylation status of five CpG residues of a CpG-rich region in the promoter of SLC6A4 by comparing female shift working nurses from a high work stress environment (n = 24) to low work stress environment (n = 25). We also analyzed the association of 5-HTTLPR polymorphism at 5′ end of SLC6A4. Work stress was assessed by the Karasek’s Model and possible signs of burnout or depression were measured by the Maslach Burnout Index General Survey and Beck Depression Index. Methylation levels were assessed by bisulfite sequencing of DNA extracted from peripheral blood leucocytes. Restriction enzyme treatment followed by standard PCR was used to identify 5-HTTLPR genotypes.
Principal Findings
We found that nurses in the high stress environment had significantly lower promoter methylation levels at all five CpG residues compared to nurses in the low stress environment (p<0.01). There was no significant interaction of 5-HTTLPR genotype and work stress with methylation (p = 0.58). In unadjusted (bivariate) analysis, burnout was not significantly associated to methylation levels. However, when mutually adjusted for both, burnout and work stress were significant contributors (p = 0.038 and p<0.0001 respectively) to methylation levels.
Conclusions
Our findings show that environmental stress is concurrent with decreased methylation of the SLC6A4 promoter. This may lead to increased transcriptional activity of the gene, increased reuptake of serotonin from synaptic clefts, and termination of the activity of serotonin. This could present a possible coping mechanism for environmental stress in humans that could eventually increase risk for disturbed functional capability and experience of depressed mood in long-term stress.
doi:10.1371/journal.pone.0045813
PMCID: PMC3461019  PMID: 23029256
10.  School environment as predictor of teacher sick leave: data-linked prospective cohort study 
BMC Public Health  2012;12:770.
Background
Poor indoor air quality (IAQ) and psychosocial problems are common in schools worldwide, yet longitudinal research on the issue is scarce. We examined whether the level of or a change in pupil-reported school environment (IAQ, school satisfaction, and bullying) predicts recorded sick leaves among teachers.
Methods
Changes in the school environment were assessed using pupil surveys at two time points (2001/02 and 2004/05) in 92 secondary schools in Finland. Variables indicating change were based on median values at baseline. We linked these data to individual-level records of teachers’ (n = 1678) sick leaves in 2001–02 and in 2004–05.
Results
Multilevel multinomial logistic regression models adjusted for baseline sick leave and covariates showed a decreased risk for short-term (one to three days) sick leaves among teachers working in schools with good perceived IAQ at both times (OR = 0.6, 95% CI: 0.5-0.9), and for those with a positive change in IAQ (OR = 0.6, 95% CI: 0.4-0.9), compared to teachers in schools where IAQ was constantly poor. Negative changes in pupil school satisfaction (OR = 1.8, 95% CI: 1.1-2.8) and bullying (OR = 1.5, 95% CI: 1.0-2.3) increased the risk for short-term leaves among teachers when compared to teachers in schools where the level of satisfaction and bullying had remained stable. School environment factors were not associated with long-term sick leaves.
Conclusions
Good and improved IAQ are associated with decreased teacher absenteeism. While pupil-related psychosocial factors also contribute to sick leaves, no effect modification or mediation of psychosocial factors on the association between IAQ and sick leave was observed.
doi:10.1186/1471-2458-12-770
PMCID: PMC3490775  PMID: 22966903
Bullying; Multilevel; Perceived indoor air; School satisfaction; Ventilation
11.  Long Working Hours and Coronary Heart Disease: A Systematic Review and Meta-Analysis 
American Journal of Epidemiology  2012;176(7):586-596.
The authors aggregated the results of observational studies examining the association between long working hours and coronary heart disease (CHD). Data sources used were MEDLINE (through January 19, 2011) and Web of Science (through March 14, 2011). Two investigators independently extracted results from eligible studies. Heterogeneity between the studies was assessed using the I2 statistic, and the possibility of publication bias was assessed using the funnel plot and Egger's test for small-study effects. Twelve studies were identified (7 case-control, 4 prospective, and 1 cross-sectional). For a total of 22,518 participants (2,313 CHD cases), the minimally adjusted relative risk of CHD for long working hours was 1.80 (95% confidence interval (CI): 1.42, 2.29), and in the maximally (multivariate-) adjusted analysis the relative risk was 1.59 (95% CI: 1.23, 2.07). The 4 prospective studies produced a relative risk of 1.39 (95% CI: 1.12, 1.72), while the corresponding relative risk in the 7 case-control studies was 2.43 (95% CI: 1.81, 3.26). Little evidence of publication bias but relatively large heterogeneity was observed. Studies varied in size, design, measurement of exposure and outcome, and adjustments. In conclusion, results from prospective observational studies suggest an approximately 40% excess risk of CHD in employees working long hours.
doi:10.1093/aje/kws139
PMCID: PMC3458589  PMID: 22952309
cardiovascular diseases; coronary disease; employment; meta-analysis; myocardial infarction; review; work
12.  Workplace social capital and all-cause mortality: A prospective cohort study of 28,043 public sector employees 
American Journal of Public Health  2011;101(9):1742-1748.
Objective
To examine the association between workplace social capital and all-cause mortality in a large occupational cohort from Finland.
Methods
Responses of 28,043 participants to surveys in 2000–2002 and 2004 were linked to national mortality registers through 2009. We used repeated measurements of self-assessed and co-workers' assessed workplace social capital. Cox proportional hazard and fixed effects logistic regressions were conducted.
Results
196 employees died during the 5-year follow-up period. A one unit increase in the mean of repeat measurements of self-assessed workplace social capital (range 1–5) was associated with a 19% decrease in the risk of all-cause mortality [age- and sex-adjusted HR=0.81; 95% CI 0.66–0.99]. The corresponding point estimate for the mean of co-workers' assessed social capital was similar, although the association was more imprecisely estimated [age- and sex-adjusted HR=0.77; 95% CI 0.50–1.20]. In fixed-effects analysis, a one unit increase in self-assessed social capital across the two time points was associated with a lower mortality risk (OR=0.81, 95% CI 0.55–1.19).
Conclusion
These findings suggest that workplace social capital is associated with decreased risk of mortality in the working-age population.
doi:10.2105/AJPH.2011.300166
PMCID: PMC3154232  PMID: 21778502
social capital; mortality; cohort study
13.  Job Strain and Tobacco Smoking: An Individual-Participant Data Meta-Analysis of 166 130 Adults in 15 European Studies 
PLoS ONE  2012;7(7):e35463.
Background
Tobacco smoking is a major contributor to the public health burden and healthcare costs worldwide, but the determinants of smoking behaviours are poorly understood. We conducted a large individual-participant meta-analysis to examine the extent to which work-related stress, operationalised as job strain, is associated with tobacco smoking in working adults.
Methodology and Principal Findings
We analysed cross-sectional data from 15 European studies comprising 166 130 participants. Longitudinal data from six studies were used. Job strain and smoking were self-reported. Smoking was harmonised into three categories never, ex- and current. We modelled the cross-sectional associations using logistic regression and the results pooled in random effects meta-analyses. Mixed effects logistic regression was used to examine longitudinal associations. Of the 166 130 participants, 17% reported job strain, 42% were never smokers, 33% ex-smokers and 25% current smokers. In the analyses of the cross-sectional data, current smokers had higher odds of job strain than never-smokers (age, sex and socioeconomic position-adjusted odds ratio: 1.11, 95% confidence interval: 1.03, 1.18). Current smokers with job strain smoked, on average, three cigarettes per week more than current smokers without job strain. In the analyses of longitudinal data (1 to 9 years of follow-up), there was no clear evidence for longitudinal associations between job strain and taking up or quitting smoking.
Conclusions
Our findings show that smokers are slightly more likely than non-smokers to report work-related stress. In addition, smokers who reported work stress smoked, on average, slightly more cigarettes than stress-free smokers.
doi:10.1371/journal.pone.0035463
PMCID: PMC3391192  PMID: 22792154
14.  Job Strain and Alcohol Intake: A Collaborative Meta-Analysis of Individual-Participant Data from 140 000 Men and Women 
PLoS ONE  2012;7(7):e40101.
Background
The relationship between work-related stress and alcohol intake is uncertain. In order to add to the thus far inconsistent evidence from relatively small studies, we conducted individual-participant meta-analyses of the association between work-related stress (operationalised as self-reported job strain) and alcohol intake.
Methodology and Principal Findings
We analysed cross-sectional data from 12 European studies (n = 142 140) and longitudinal data from four studies (n = 48 646). Job strain and alcohol intake were self-reported. Job strain was analysed as a binary variable (strain vs. no strain). Alcohol intake was harmonised into the following categories: none, moderate (women: 1–14, men: 1–21 drinks/week), intermediate (women: 15–20, men: 22–27 drinks/week) and heavy (women: >20, men: >27 drinks/week). Cross-sectional associations were modelled using logistic regression and the results pooled in random effects meta-analyses. Longitudinal associations were examined using mixed effects logistic and modified Poisson regression. Compared to moderate drinkers, non-drinkers and (random effects odds ratio (OR): 1.10, 95% CI: 1.05, 1.14) and heavy drinkers (OR: 1.12, 95% CI: 1.00, 1.26) had higher odds of job strain. Intermediate drinkers, on the other hand, had lower odds of job strain (OR: 0.92, 95% CI: 0.86, 0.99). We found no clear evidence for longitudinal associations between job strain and alcohol intake.
Conclusions
Our findings suggest that compared to moderate drinkers, non-drinkers and heavy drinkers are more likely and intermediate drinkers less likely to report work-related stress.
doi:10.1371/journal.pone.0040101
PMCID: PMC3391232  PMID: 22792218
15.  Is retirement beneficial for mental health? Antidepressant use before and after retirement 
Epidemiology (Cambridge, Mass.)  2011;22(4):553-559.
Background
Recent studies based on self-reported data suggest that retirement may have beneficial effects on mental health, but studies using objective endpoints remain scarce. This study examines longitudinally the changes in antidepressant medication use across the 9 years spanning the transition to retirement.
Methods
Participants were Finnish public-sector employees: 7138 retired at statutory retirement age (76% women, mean age 61.2 years), 1238 retired early due to mental health issues (78% women, mean age 52.0 years), and 2643 retired due to physical health issues(72% women, mean age 55.4 years). Purchase of antidepressant medication four years prior to and four years after retirement year were based on comprehensive national pharmacy records in 1994-2005.
Results
One year before retirement, the use of antidepressants was 4% among those who would retire at statutory age, 61% among those who would retire due to mental health issues, and 14% among those who would retire due to physical health issues. Retirement-related changes in antidepressant use depended on the reason for retirement. Among old-age retirees, antidepressant medication use decreased during the transition period (age- and calendar-year-adjusted prevalence ratio for antidepressant use 1 year after vs. 1 year before retirement = 0.77 [95% confidence interval = 0.68 – 0.88]). Among those whose main reason for disability pension was mental health issues or physical health issues, there was an increasing trend in antidepressant use prior to retirement and, for mental health retirements, a decrease after retirement.
Conclusions
Trajectories of recorded purchases of antidepressant medication are consistent with the hypothesis that retirement is beneficial for mental health.
doi:10.1097/EDE.0b013e31821c41bd
PMCID: PMC3132597  PMID: 21502864
16.  Stressful life events and the onset of asthma 
The European Respiratory Journal  2010;37(6):1360-1365.
The status of stressful life events as a risk factor for asthma is unclear and may be dependent on pre-existing allergic rhinitis. This study examined whether exposure to stressful life events predicted the onset of asthma in adults.
This is a prospective, population-based cohort study of 16,881 men and women, aged 20–54 and free of diagnosed asthma at the beginning of the follow-up (January 1, 2004). Data about stressful life events were gathered with a postal survey. The onset of asthma was ascertained through national registers until December 31, 2005.
During the follow-up period, 192 incident cases of asthma were identified. High total exposure to stressful life events, as indicated by a cumulative severity score, predicted the onset of asthma (HR 1.96; 95% CI 1.22–3.13). This association was robust to adjustment for demographics, smoking, and having a cat/dog at home, and it was observed both among those with and without allergic rhinitis at the baseline. Of the 10 most stressful life events, the illness of a family member, marital problems, divorce or separation, and conflicts with a supervisor were associated with the onset of asthma.
Our study suggests that stressful life events may increase the onset of asthma.
doi:10.1183/09031936.00164609
PMCID: PMC3319299  PMID: 21030455
asthma; asthma epidemiology; asthma onset; stressful life events
17.  Influence of retirement and work stress on headache prevalence: a longitudinal modelling study from the GAZEL Cohort Study 
Cephalalgia  2011;31(6):696-705.
Aims
To examine trajectories of headache in relation to retirement and to clarify the role of work stress and stress-prone personality.
Methods
Headache prevalence during seven years before and after retirement was measured by annual questionnaires from GAZEL cohort comprising French national gas and electricity company employees (N=12,913). Odds ratios and 95% confidence intervals for headache during pre- peri- and post-retirement were calculated. The role of effect modifiers (work stress, type A or hostile personality) was tested by multiplicative interactions and synergy indices.
Results
11%–13% reduction in headache prevalence was found during pre- and post-retirement, whereas decline was much steeper (46%) during the retirement transition. In absolute terms, the decline was greater among persons with high work stress or stress-prone personality than among other participants.
Conclusions
Retirement is associated with a decrease in headache prevalence, particularly among persons with high amount of work stress or proneness to overreact to stress.
doi:10.1177/0333102410394677
PMCID: PMC3317892  PMID: 21220374
headache; retirement; work stress; stress-prone personality
18.  INFLUENCE OF RETIREMENT AND WORK STRESS ON HEADACHE PREVALENCE: A LONGITUDINAL MODELLING STUDY FROM THE GAZEL COHORT 
Cephalalgia  2011;31(6):696-705.
Aims
To examine trajectories of headache in relation to retirement and to clarify the role of work stress and stress-prone personality.
Methods
Headache prevalence during seven years before and after retirement was measured by annual questionnaires from GAZEL cohort comprising French national gas and electricity company employees (N=12,913). Odds ratios and 95% confidence intervals for headache during pre- peri- and post-retirement were calculated. The role of effect modifiers (work stress, type A or hostile personality) was tested by multiplicative interactions and synergy indices.
Results
11%-13% reduction in headache prevalence was found during pre- and post-retirement, whereas decline was much steeper (46%) during the retirement transition. In absolute terms, the decline was greater among persons with high work stress or stress-prone personality than among other participants.
Conclusions
Retirement is associated with a decrease in headache prevalence, particularly among persons with high amount of work stress or proneness to overreact to stress.
doi:10.1177/0333102410394677
PMCID: PMC3317892  PMID: 21220374
headache; retirement; work stress; stress-prone personality
19.  Obesity, unexplained weight loss and suicide: The original Whitehall study 
Journal of Affective Disorders  2008;116(3):218-221.
Background
Evidence on the association between obesity and suicide is mixed. However, the strength of obesity as a predictor of suicide may be reduced, because of the role of weight changes associated with mental disorders. We tested the hypothesis that both obesity and unexplained weight loss are related to elevated suicide risk.
Methods
A clinical examination with measurements of height, weight and self-reported unexplained weight loss was conducted at baseline for 18,784 men aged 40 to 69. Based on national mortality register, 61 suicides were identified during the 38-year follow-up.
Results
The age-adjusted hazard ratio for suicide among obese versus normal weight men was 2.22 (95% CI 0.94 to 5.28). Additional adjustment for unexplained weight loss raised this ratio to 2.48 (95% CI 1.04 to 5.92). Unexplained weight loss was associated with a substantial excess risk of suicide irrespective of obesity (age-adjusted hazard ratio 5.38, 95% CI 2.31 to 12.50; age- and obesity-adjusted hazard ratio 5.58, 95% CI 2.37 to 13.13).
Limitations
Inability to take into account the effect of depression as a potential mediating mechanism.
Conclusions
This study provides evidence that both obesity and unexplained weight loss may be important predictors of suicide. Lack of adjustment for weight loss may suppress the observed association between obesity and suicide.
doi:10.1016/j.jad.2008.12.002
PMCID: PMC3319297  PMID: 19097646
BMI; overweight; public sector; suicide; weight loss; work
20.  Waterborne Outbreak of Gastroenteritis: Effects on Sick Leaves and Cost of Lost Workdays 
PLoS ONE  2012;7(3):e33307.
Background
In 2007, part of a drinking water distribution system was accidentally contaminated with waste water effluent causing a gastroenteritis outbreak in a Finnish town.
We examined the acute and cumulative effects of this incidence on sick leaves among public sector employees residing in the clean and contaminated areas, and the additional costs of lost workdays due to the incidence.
Methods
Daily information on sick leaves of 1789 Finnish Public Sector Study participants was obtained from employers' registers. Global Positioning System-coordinates were used for linking participants to the clean and contaminated areas. Prevalence ratios (PR) for weekly sickness absences were calculated using binomial regression analysis. Calculations for the costs were based on prior studies.
Results
Among those living in the contaminated areas, the prevalence of participants on sick leave was 3.54 (95% confidence interval (CI) 2.97–4.22) times higher on the week following the incidence compared to the reference period. Those living and working in the clean area were basically not affected, the corresponding PR for sick leaves was 1.12, 95% CI 0.73–1.73. No cumulative effects on sick leaves were observed among the exposed. The estimated additional costs of lost workdays due to the incidence were 1.8–2.1 million euros.
Conclusions
The prevalence of sickness absences among public sector employees residing in affected areas increased shortly after drinking water distribution system was contaminated, but no long-term effects were observed. The estimated costs of lost workdays were remarkable, thus, the cost-benefits of better monitoring systems for the water distribution systems should be evaluated.
doi:10.1371/journal.pone.0033307
PMCID: PMC3307726  PMID: 22442683
21.  Non-response in a nationwide follow-up postal survey in Finland: a register-based mortality analysis of respondents and non-respondents of the Health and Social Support (HeSSup) Study 
BMJ Open  2012;2(2):e000657.
Objective
To examine difference in mortality between postal survey non-respondents and respondents.
Design
A prospective cohort study with baseline survey in 1998 and comprehensive linkage to national mortality registers until 2005, the Health and Social Support study.
Setting
A population-based postal survey of the working-aged population in Finland in 1998.
Participants
The original random sample comprised 64 797 working-aged individuals in Finland (20–24, 30–34, 40–44, 50–54 years of age; 32 059 women and 32 716 men), yielding 25 898 (40.0%) responses in the baseline postal survey in 1998.
Primary outcome measure
Registry-based primary causes of death encoded with the International Classification of Diseases (ICD-10).
Results
In women, HR for total mortality was 1.75 (95% CI 1.40 to 2.19) times higher among the non-respondents compared with the respondents. In men, non-response was associated with a 1.41-fold (1.21–1.65) excess risk of total mortality. Non-response associated in certain age groups with deaths due to diseases in women and with deaths due to external causes in men. The most prominent excess mortality was seen for total mortality for both genders and for mortality due to external causes among men.
Conclusions
Postal surveys result in slight underestimation of illness prevalence.
Article summary
Article focus
Women and individuals from upper social strata tend to participate more actively in postal health surveys.
What this exactly means in terms of health selection among respondents is unclear.
Postal health surveys are believed to produce underestimates of illness prevalence.
Key messages
Total mortality was consistently and for women in the age group ≥50 years and for men in the age groups ≥40 years significantly higher among non-respondents compared with respondents during a 7-year follow-up among a total Finnish nationwide sample in working age comprising almost 65 000 individuals.
The excess mortality observed was 1.5–2 fold. Among men, it was explained by external causes, whereas among women, it was due to diseases and was statistically significant only in the age group 50–54 years.
Postal surveys result in slight underestimation of illness prevalence.
Strengths and limitations of the study
The linkage to mortality data was successful for virtually all individuals of the original sample comprising nearly 65 000 individuals. The sample size secures the reliability of the conclusions drawn. Furthermore, the registry data on mortality in Finland can be considered as reliable. To the best of the authors' knowledge, a corresponding study based on an as large a sample as in this study has not previously been carried out.
Some inaccuracy concerning the final diagnosis of death is possible. A further study limitation is that data of socioeconomic status or educational level of non-respondents were not available, and hence, adjustments of the statistical analyses for these variables were not possible.
doi:10.1136/bmjopen-2011-000657
PMCID: PMC3307122  PMID: 22422917
22.  Quantifying Neighbourhood Socioeconomic Effects in Clustering of Behaviour-Related Risk Factors: A Multilevel Analysis 
PLoS ONE  2012;7(3):e32937.
Background
The extent to which neighbourhood characteristics explain accumulation of health behaviours is poorly understood. We examined whether neighbourhood disadvantage was associated with co-occurrence of behaviour-related risk factors, and how much of the neighbourhood differences in the co-occurrence can be explained by individual and neighbourhood level covariates.
Methods
The study population consisted of 60 694 Finnish Public Sector Study participants in 2004 and 2008. Neighbourhood disadvantage was determined using small-area level information on household income, education attainment, and unemployment rate, and linked with individual data using Global Positioning System-coordinates. Associations between neighbourhood disadvantage and co-occurrence of three behaviour-related risk factors (smoking, heavy alcohol use, and physical inactivity), and the extent to which individual and neighbourhood level covariates explain neighbourhood differences in co-occurrence of risk factors were determined with multilevel cumulative logistic regression.
Results
After adjusting for age, sex, marital status, and population density we found a dose-response relationship between neighbourhood disadvantage and co-occurrence of risk factors within each level of individual socioeconomic status. The cumulative odds ratios for the sum of health risks comparing the most to the least disadvantaged neighbourhoods ranged between 1.13 (95% confidence interval (CI): 1.03–1.24) and 1.75 (95% CI, 1.54–1.98). Individual socioeconomic characteristics explained 35%, and neighbourhood disadvantage and population density 17% of the neighbourhood differences in the co-occurrence of risk factors.
Conclusions
Co-occurrence of poor health behaviours associated with neighbourhood disadvantage over and above individual's own socioeconomic status. Neighbourhood differences cannot be captured using individual socioeconomic factors alone, but neighbourhood level characteristics should also be considered.
doi:10.1371/journal.pone.0032937
PMCID: PMC3299718  PMID: 22427912
23.  Long working hours and symptoms of anxiety and depression: a 5-year follow-up of the Whitehall II study 
Background
Although long working hours are common in working populations, little is known about the effect of long working hours on mental health.
Method
We examined the association between long working hours and onset of depressive and anxiety symptoms in middle-aged employees. Participants were 2960 full-time employees aged 44 to 66 (2248 men, 712 women) from the prospective Whitehall II cohort study of British civil servants. Working hours, anxiety and depressive symptoms, and covariates were measured at baseline (1997–1999) followed by two subsequent measurements of depressive and anxiety symptoms (2001 and 2002–2004).
Results
In prospective analysis of participants with no depressive symptoms (n=2549) or anxiety symptoms (n=2618) at baseline, Cox proportional hazard analysis adjusted for baseline covariates showed a 1.66-fold (95% CI 1.06–2.61) risk of depressive symptoms and a 1.74-fold (1.15–2.61) risk of anxiety symptoms among employees working more than 55 hours a week compared with employees working 35–40 hours a week. Sex-stratified analysis showed an excess risk of depression and anxiety associated with long working hours among women [hazard ratios 2.67 (1.07–6.68) and 2.84 (1.27–6.34)] but not men [1.30 (0.77–2.19) and 1.43 (0.89–2.30)].
Conclusions
Working long hours is a risk factor for development of depressive and anxiety symptoms in women.
doi:10.1017/S0033291711000171
PMCID: PMC3095591  PMID: 21329557
Work hours; depression; anxiety; overtime work; prospective
24.  Change in physical activity and weight in relation to retirement: the French GAZEL Cohort Study 
BMJ Open  2012;2(1):e000522.
Objectives
To examine the trajectories of physical activity from preretirement to postretirement and to further clarify whether the changes in physical activity are associated with changes in body weight.
Design
Prospective.
Setting
French national gas and electricity company (GAZEL cohort).
Participants
From the original sample of 20 625 employees, only those retiring between 2001 and 2008 on a statutory basis were selected for the analyses (analysis 1: n=2711, 63% men; analysis 2: n=3812, 75% men). Persons with data on at least one preretirement and postretirement measurement of the outcome were selected.
Primary and secondary outcome measures
All outcome data were gathered by questionnaires. In analysis 1, the annual prevalence of higher physical activity (walking ≥5 km/week) 4 years before and after retirement was analysed. In analysis 2, changes in leisure-time sport activities (engagement, frequency and manner) from preretirement to postretirement were analysed with simultaneous changes in body weight (kilogram).
Results
In analysis 1 (n=2711), prevalence estimates for 4 years before and 4 years after retirement showed that higher leisure-time physical activity (walking at least 5 km/week) increased by 36% in men and 61% in women during the transition to retirement. This increase was also observed among people at a higher risk of physical inactivity, such as smokers and those with elevated depressive symptoms. In a separate sample (analysis 2, n=3812), change in weight as a function of preretirement and postretirement physical activity was analysed. Weight gain preretirement to postretirement was 0.85 (95% CI 0.48 to 1.21) to 1.35 (0.79 to 1.90) kg greater among physically inactive persons (decrease in activity or inactive) compared with those physically active (p<0.001).
Conclusions
Retirement transition may be associated with beneficial changes in lifestyle and may thus be a good starting point to preventive interventions in various groups of individuals in order to maintain long-term changes.
Article summary
Article focus
The main focus of this article was to examine whether statutory retirement is associated with changes in physical activity.
Especially, we wanted to clarify what happens during the actual retirement transition (ie, the year of retirement ±1 year).
Furthermore, we examined whether there were changes in body weight as a function of preretirement and postretirement physical activity level.
Key messages
We were able to show that during a 9-year follow-up physical activity increased most during the retirement transition, both in men and women.
Beneficial changes were noticed also among those usually considered as low physical activity groups, such as smokers.
Physically inactive persons were most prone to gain weight during the follow-up.
Strengths and limitations of this study
The main strength of this study was yearly measurements of the outcome, which enabled us to get accurate estimates of physical activity during the actual retirement transition.
Large and stable occupational cohort, prospective study design, accurate register-based data on retirement and long follow-up both preretirement and postretirement were other strengths of this study.
The main limitation was the use of self-report data of the outcome.
doi:10.1136/bmjopen-2011-000522
PMCID: PMC3277904  PMID: 22318663
Body weight changes; exercise; longitudinal studies; retirement
25.  Sleep Disturbances and Cause-Specific Mortality: Results From the GAZEL Cohort Study 
American Journal of Epidemiology  2010;173(3):300-309.
Poor sleep is an increasing problem in modern society, but most previous studies on the association between sleep and mortality rates have addressed only duration, not quality, of sleep. The authors prospectively examined the effects of sleep disturbances on mortality rates and on important risk factors for mortality, such as body mass index, hypertension, and diabetes. A total of 16,989 participants in the GAZEL cohort study were asked validated questions on sleep disturbances in 1990 and were followed up until 2009, with <1% loss to follow-up. Body mass index, hypertension, and diabetes were measured annually through self-reporting. During follow-up, a total of 1,045 men and women died. Sleep disturbances were associated with a higher overall mortality risk in men (P = 0.005) but not in women (P = 0.33). This effect was most pronounced for men <45 years of age (≥3 symptoms vs. none: hazard ratio = 2.03, 95% confidence interval: 1.24, 3.33). There were no clear associations between sleep disturbances and cardiovascular mortality rates, although men and women with sleep disturbances were more likely to develop hypertension and diabetes (P < 0.001). Compared with people with no sleep disturbances, men who reported ≥3 types of sleep disturbance had an almost 5 times' higher risk of committing suicide (hazard ratio = 4.99, 95% confidence interval: 1.59, 15.7). Future strategies to prevent premature deaths may benefit from assessment of sleep disturbances, especially in younger individuals.
doi:10.1093/aje/kwq371
PMCID: PMC3105272  PMID: 21193534
body mass index; cause of death; diabetes mellitus; hypertension; longitudinal studies; mortality; sleep disorders

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