Sex differences in functional limitation level and the role of socioeconomic factors

Background

Women are more likely to have functional limitations than men, partly due to socioeconomic disadvantage. As much of this research is based on dichotomised measures of limitation, how sex differences vary by level of limitations remains unclear. The aim of our study was to examine sex differences in functional limitations in people born between 1895 and 1960, with attention to the role of socioeconomic factors and level of limitations.

Methods

Longitudinal data on limitations in basic/instrumental activities of daily living (ADL/IADL) and mobility activities were drawn from studies in 14 countries. For ADL, IADL, and mobility activities, participants were grouped into limitation levels based on number of limited activities (0, 1, 2, or ≥ 3). Sex differences in limitations in four birth cohorts (1895-1929, 1930-1938, 1939-1945, 1946-1960) were analysed before and after adjustment for socioeconomic factors using mixed effects ordinal logistic models.

Findings

Among 62,375 participants, sex differences in IADL and ADL limitations (≥1) were minor after adjustment for socioeconomic factors (sex difference in probability of limitations (female - male) age 75, 1895-1929 cohort for IADL=3.7% (95% CI 2.6, 4.7) before and 1.7% (1.1, 2.2) after adjustment; ADL=3.2% (2.3, 4.1) before, 1.4% (0.9, 1.8) after). Sex differences remained for mobility (16.1% (14.4, 17.7) before, 14.3% (12.7, 15.9) after). At older ages, women were more likely to have ≥3 IADL or mobility limitations, while men were more likely to have 1 to 2.

Conclusions

Socioeconomic factors explain the majority of sex differences in IADL and ADL limitations but not mobility, with women reporting greater mobility limitations than men starting in middle age. Our findings suggest sex differences in mobility limitations from middle age might be important targets for future study and interventions.

Key messages

Sex differences in disability vary considerably between disability measures. Comprehensive assessment of sex differences in disability should consider disability severity across different measures. Findings suggest there may be fewer sex differences in disability in the future with progressively decreasing socioeconomic disparities between men and women.

Association of big-5 personality traits with cognitive impairment and dementia: a longitudinal study

BACKGROUND

Personality traits have been liked to cognitive outcomes such as dementia, but whether these associations are robust to the effects of third variables remains the subject of debate. We examined the role of socioeconomic status, depression (history and depressive symptoms), health behaviours and chronic conditions in the association of the big-5 personality traits with cognitive performance, cognitive impairment and incidence of dementia.

METHODS

Data on 6135 persons (30% women), aged 60-83 years in 2012/13, are drawn from the Whitehall II Study. Participants responded to the 26-item Midlife Development Inventory to assess personality traits (openness, conscientiousness, extraversion, agreeableness and neuroticism), underwent cognitive testing in 2012/13 and 2015/16 and were followed for incidence of dementia (N=231) until 2019.

RESULTS

Logistic regression, adjusted for sociodemographic factors, suggested a cross-sectional association with cognitive impairment for four of the five traits but only neuroticism was associated with incident cognitive impairment. All associations were completely attenuated when the analyses were adjusted for depression. Cox regression (mean follow-up: 6.18 years) adjusted for sociodemographic variables showed higher conscientiousness (HR per SD increment=0.72; 95% CI 0.65 to 0.81) and extraversion (HR=0.85; 95% CI 0.75 to 0.97) to be associated with lower dementia risk; higher neuroticism (HR=1.32; 95% CI 1.17 to 1.49) was associated with increased risk. Further adjustment for depression led to only conscientiousness retaining an association with dementia (HR=0.81; 95% CI 0.69 to 0.96), which was robust to adjustment for all covariates (HR=0.84; 95% CI 0.71 to 0.91; P=0.001).

CONCLUSION

Our results show that only conscientiousness has an association with incidence of dementia that is not attributable to socioeconomic status or depression. The association of neuroticism with dementia was explained by depression.

Healthy obesity and risk of accelerated functional decline and disability

BACKGROUND/OBJECTIVES

Some obese adults have a normal metabolic profile and are considered 'healthy', but whether they experience faster ageing than healthy normal-weight adults is unknown. We compared decline in physical function, worsening of bodily pain and likelihood of future mobility limitation and disability between these groups.

SUBJECTS/METHODS

This was a population-based observational study using repeated measures over 2 decades (Whitehall II cohort data). Normal-weight (body mass index (BMI) 18.5-24.9 kg m-2), overweight (25.0-29.9 kg m-2) and obese (⩾30.0 kg m-2) adults were considered metabolically healthy if they had 0 or 1 of 5 risk factors (hypertension, low high-density lipoprotein cholesterol, high triacylglycerol, high blood glucose and insulin resistance) in 1991/1994. Decline in physical function and worsening of bodily pain based on change in Short Form Health Survey items using eight repeated measures over 18.8 years (1991/1994-2012/2013) were compared between metabolic-BMI groups using linear mixed models. Odds of mobility limitation based on objective walking speed (slowest tertile) and of disability based on limitations in ⩾1 of 6 basic activities of daily living, each using three repeated measures over 8.3 years (2002/2004-2012/2013), were compared using logistic mixed models.

RESULTS

In multivariable-adjusted mixed models on up to 6635 adults (initial mean age 50 years; 70% male), healthy normal-weight adults experienced a decline in physical function of -3.68 (95% CI=-4.19, -3.16) score units per decade; healthy obese adults showed an additional -3.48 (-4.88, -2.08) units decline. Healthy normal-weight adults experienced a -0.49 (-1.11, 0.12) score unit worsening of bodily pain per decade; healthy obese adults had an additional -2.23 (-3.78, -0.69) units worsening. Healthy obesity versus healthy normal-weight conferred 3.39 (2.29, 5.02) times higher odds of mobility limitation and 3.75 (1.94, 7.24) times higher odds of disability.

CONCLUSIONS

Our results suggest that obesity, even if metabolically healthy, accelerates age-related declines in functional ability and poses a threat to independence in older age.

Job strain as a risk factor for clinical depression: systematic review and meta-analysis with additional individual participant data

BACKGROUND

Adverse psychosocial working environments characterized by job strain (the combination of high demands and low control at work) are associated with an increased risk of depressive symptoms among employees, but evidence on clinically diagnosed depression is scarce. We examined job strain as a risk factor for clinical depression.

METHOD

We identified published cohort studies from a systematic literature search in PubMed and PsycNET and obtained 14 cohort studies with unpublished individual-level data from the Individual-Participant-Data Meta-analysis in Working Populations (IPD-Work) Consortium. Summary estimates of the association were obtained using random-effects models. Individual-level data analyses were based on a pre-published study protocol.

RESULTS

We included six published studies with a total of 27 461 individuals and 914 incident cases of clinical depression. From unpublished datasets we included 120 221 individuals and 982 first episodes of hospital-treated clinical depression. Job strain was associated with an increased risk of clinical depression in both published [relative risk (RR) = 1.77, 95% confidence interval (CI) 1.47-2.13] and unpublished datasets (RR = 1.27, 95% CI 1.04-1.55). Further individual participant analyses showed a similar association across sociodemographic subgroups and after excluding individuals with baseline somatic disease. The association was unchanged when excluding individuals with baseline depressive symptoms (RR = 1.25, 95% CI 0.94-1.65), but attenuated on adjustment for a continuous depressive symptoms score (RR = 1.03, 95% CI 0.81-1.32).

CONCLUSIONS

Job strain may precipitate clinical depression among employees. Future intervention studies should test whether job strain is a modifiable risk factor for depression.

Cross-sectional analysis of deprivation and ideal cardiovascular health in the Paris Prospective Study 3

AIMS

We hypothesised that deprivation might represent a barrier to attain an ideal cardiovascular health (CVH) as defined by the American Heart Association (AHA).

METHODS AND RESULTS

The baseline data of 8916 participants of the Paris Prospective Study 3, an observational cohort on novel markers for future cardiovascular disease, were used. The AHA 7-item tool includes four health behaviours (smoking, body weight, physical activity and optimal diet) and three biological measures (blood cholesterol, blood glucose and blood pressure). A validated 11-item score of individual material and psychosocial deprivation, the Evaluation de la Précarité et des Inégalités dans les Centres d'Examens de Santé-Evaluation of Deprivation and Inequalities in Health Examination centres (EPICES) score was used. The mean age was 59.5 years (standard deviation 6.2), 61.2% were men and 9.98% had an ideal CVH. In sex-specific multivariable polytomous logistic regression, the odds ratio (OR) for ideal behavioural CVH progressively decreased with quartile of increasing deprivation, from 0.54 (95% CI 0.41 to 0.72) to 0.49 (0.37 to 0.65) in women and from 0.61 (0.50 to 0.76) to 0.57 (0.46 to 0.71) in men. Associations with ideal biological CVH were confined to the most deprived women (OR=0.60; 95% CI 0.37 to 0.99), whereas in men, greater deprivation was related to higher OR of intermediate biological CVH (OR=1.28; 95% CI 1.05 to 1.57 for the third quartile vs the first quartile).

CONCLUSIONS

Higher material and psychosocial deprivation may represent a barrier to reach an ideal CVH.

TRIAL REGISTRATION NUMBER

NCT00741728.

Interleukin-6 as a predictor of symptom resolution in psychological distress: a cohort study

BACKGROUND

Elevated levels of interleukin-6 (IL-6) have been associated with the development of common mental disorders, such as depression, but its role in symptom resolution is unclear.

METHOD

We examined the association between IL-6 and symptom resolution in a non-clinical sample of participants with psychological distress.

RESULTS

Relative to high IL-6 levels, low levels at baseline were associated with symptom resolution at follow-up [age- and sex-adjusted risk ratio (RR) = 1.15, 95% confidence interval (CI) 1.06-1.25]. Further adjustment for covariates had little effect on the association. Symptomatic participants with repeated low IL-6 were more likely to be symptom-free at follow-up compared with those with repeated high IL-6 (RR = 1.21, 95% CI 1.03-1.41). Among the symptomatic participants with elevated IL-6 at baseline, IL-6 decreased along with symptom resolution.

CONCLUSIONS

IL-6 is potentially related to the mechanisms underlying recovery from symptoms of mental ill health. Further studies are needed to examine these mechanisms and to confirm the findings in relation to clinical depression.

Job strain and risk of obesity: systematic review and meta-analysis of cohort studies

Job strain, the most widely used indicator of work stress, is a risk factor for obesity-related disorders such as cardiovascular disease and type 2 diabetes. However, the extent to which job strain is related to the development of obesity itself has not been systematically evaluated. We carried out a systematic review (PubMed and Embase until May 2014) and meta-analysis of cohort studies to address this issue. Eight studies that fulfilled inclusion criteria showed no overall association between job strain and the risk of weight gain (pooled odds ratio for job strain compared with no job strain 1.04, 95% confidence interval (CI) 0.99–1.09, N_Total=18 240) or becoming obese (1.00, 95% CI 0.89–1.13, N_Total=42 222). In addition, a reduction in job strain over time was not associated with lower obesity risk (1.13, 95% CI 0.90–1.41, N_Total=6507). These longitudinal findings do not support the hypothesis that job strain is an important risk factor for obesity or a promising target for obesity prevention.

Excess non-psychiatric hospitalizations among employees with mental disorders: a 10-year prospective study of the GAZEL cohort

OBJECTIVE

To examine whether non-psychiatric hospitalizations rates were higher in those with mental disorders.

METHOD

In a cohort of 15,811 employees, aged 35-50 years in 1989, mental disorder status was defined from 1989 to 2000. Hospitalizations for all-causes, myocardial infarction (MI), stroke, and cancer, were recorded yearly from 2001 to 2011. Negative binomial regression models were used to estimate hospitalization rates over the follow-up.

RESULTS

After controlling for baseline sociodemographic factors, health-related behaviors, self-rated health, and self-reported medical conditions, participants with a mental disorder had significantly higher rates of all-cause hospitalization [incidence rate ratio, IRR=1.20 (95%, 1.14-1.26)], as well as hospitalization due to MI [IRR=1.44 (95%, 1.12-1.85)]. For stroke, the IRR did not reach statistical significance [IRR=1.37 (95%, 0.95-1.99)] and there was no association with cancer [IRR=1.01 (95%, 0.86-1.19)]. A similar trend was observed when mental disorders groups were considered (no mental disorder, depressive disorder, mental disorders due to psychoactive substance use, other mental disorders, mixed mental disorders, and severe mental disorder).

CONCLUSION

In this prospective cohort of employees with stable employment as well as universal access to healthcare, we found participants with mental disorders to have higher rates of non-psychiatric hospitalizations.

Personality change associated with chronic diseases: pooled analysis of four prospective cohort studies

BACKGROUND

Common chronic conditions, such as heart disease and cancer, are associated with increased psychological distress, functional limitations and shortened life expectancy, but whether these diseases alter aspects of personality remains unclear.

METHOD

To examine whether the onset of heart disease, stroke, diabetes, cancer, hypertension, arthritis and respiratory disease is associated with subsequent changes in personality traits of the five-factor model, we pooled data from the Health and Retirement Study, the Midlife in the United States Survey, and the graduate and sibling samples of the Wisconsin Longitudinal Study for an individual-participant meta-analysis (total n=17,493; mean age at baseline 55.8 years).

RESULTS

After adjustment for age, we observed consistent decreases in extraversion [-0.25 T-scores per one disease; 95% confidence interval (CI) -0.40 to -0.10], emotional stability (-0.40, 95% CI -0.61 to -0.19), conscientiousness (-0.44, 95% CI -0.57 to -0.30) and openness to experience (-0.25, 95% CI -0.37 to -0.13) but not in agreeableness (-0.05, 95% CI -0.19 to 0.08) after the onset of chronic diseases. The onset of each additional chronic disease accelerated the average age-related personality change by 2.5 years in decreasing extraversion, 5.5 years in decreasing conscientiousness, and 1.6 years in decreasing openness to experience, and attenuated the increasing levels of emotional stability by 1.9 years. Co-morbid conditions were associated with larger changes than single diseases, suggesting a dose-response association between morbidity and personality change.

CONCLUSIONS

These results support the hypothesis that chronic diseases influence personality development in adulthood.

Job strain and the risk of severe asthma exacerbations: a meta-analysis of individual-participant data from 100 000 European men and women

Background

Many patients and healthcare professionals believe that work‐related psychosocial stress, such as job strain, can make asthma worse, but this is not corroborated by empirical evidence. We investigated the associations between job strain and the incidence of severe asthma exacerbations in working‐age European men and women.

Methods

We analysed individual‐level data, collected between 1985 and 2010, from 102 175 working‐age men and women in 11 prospective European studies. Job strain (a combination of high demands and low control at work) was self‐reported at baseline. Incident severe asthma exacerbations were ascertained from national hospitalization and death registries. Associations between job strain and asthma exacerbations were modelled using Cox regression and the study‐specific findings combined using random‐effects meta‐analyses.

Results

During a median follow‐up of 10 years, 1 109 individuals experienced a severe asthma exacerbation (430 with asthma as the primary diagnostic code). In the age‐ and sex‐adjusted analyses, job strain was associated with an increased risk of severe asthma exacerbations defined using the primary diagnostic code (hazard ratio, HR: 1.27, 95% confidence interval, CI: 1.00, 1.61). This association attenuated towards the null after adjustment for potential confounders (HR: 1.22, 95% CI: 0.96, 1.55). No association was observed in the analyses with asthma defined using any diagnostic code (HR: 1.01, 95% CI: 0.86, 1.19).

Conclusions

Our findings suggest that job strain is probably not an important risk factor for severe asthma exacerbations leading to hospitalization or death.

Physical activity patterns over 10 years in relation to body mass index and waist circumference: the Whitehall II cohort study

OBJECTIVE

Physical activity patterns over 10-years in relation to changes in body mass index (BMI) and waist circumference (WC) were examined.

DESIGN AND METHODS

Participants (4,880, mean age 49.3 years at baseline) from the Whitehall II cohort study were included. Self-reported physical activity and anthropometric data were collected at baseline (1991) and twice during follow-up (1997 and 2002).

RESULTS

At baseline, meeting established guidelines for physical activity, particularly through vigorous activity, was associated with lower WC (multivariable adjusted B compared to not meeting the guidelines -2.08 cm, 95% CI, -1.39, -0.75) and BMI (-0.34 kg/m(2) , -0.10, -0.59). Based on repeat data, "high adherence" to the guidelines compared to "rare adherence" over follow-up was associated with lower BMI (adjusted difference, -0.43 kg/m(2) , 95% CI, -0.79, -0.08) and WC (-2.50 cm, 95% CI, -3.46, -1.54) at follow-up. Compared to participants that remained stable between 1997 and 2002 (change of <2.5 h/week), those that reported an increase in moderate-vigorous physical activity of at least 2.5 h/week displayed lower BMI (-0.40 kg/m(2) , 95% CI, -0.71, -0.08) and WC (-1.10 cm, 95% CI, -1.95, -0.75).

CONCLUSION

Regular physical activity, confirmed by repeated assessments, is associated with relatively favorable levels of adiposity markers after 10 years follow-up.

Association of personality with the development and persistence of obesity: a meta-analysis based on individual-participant data

Personality is thought to affect obesity risk but before such information can be incorporated into prevention and intervention plans, robust and converging evidence concerning the most relevant personality traits is needed. We performed a meta-analysis based on individual-participant data from nine cohort studies to examine whether broad-level personality traits predict the development and persistence of obesity (n = 78,931 men and women; mean age 50 years). Personality was assessed using inventories of the Five-Factor Model (extraversion, neuroticism, agreeableness, conscientiousness and openness to experience). High conscientiousness - reflecting high self-control, orderliness and adherence to social norms - was associated with lower obesity risk across studies (pooled odds ratio [OR] = 0.84; 95% confidence interval [CI] = 0.80-0.88 per 1 standard deviation increment in conscientiousness). Over a mean follow-up of 5.4 years, conscientiousness predicted lower obesity risk in initially non-obese individuals (OR = 0.88, 95% CI = 0.85-0.92; n = 33,981) and was associated with greater likelihood of reversion to non-obese among initially obese individuals (OR = 1.08, 95% CI = 1.01-1.14; n = 9,657). Other personality traits were not associated with obesity in the pooled analysis, and there was substantial heterogeneity in the associations between studies. The findings indicate that conscientiousness may be the only broad-level personality trait of the Five-Factor Model that is consistently associated with obesity across populations.

Occupational solvent exposure and cognition: does the association vary by level of education?

OBJECTIVE

Chronic occupational solvent exposure is associated with long-term cognitive deficits. Cognitive reserve may protect solvent-exposed workers from cognitive impairment. We tested whether the association between chronic solvent exposure and cognition varied by educational attainment, a proxy for cognitive reserve.

METHODS

Data were drawn from a prospective cohort of French national gas and electricity (GAZEL) employees (n = 4,134). Lifetime exposure to 4 solvent types (chlorinated solvents, petroleum solvents, benzene, and nonbenzene aromatic solvents) was assessed using a validated job-exposure matrix. Education was dichotomized at less than secondary school or below. Cognitive impairment was defined as scoring below the 25th percentile on the Digit Symbol Substitution Test at mean age 59 (SD 2.8; 88% of participants were retired at testing). Log-binomial regression was used to model risk ratios (RRs) for poor cognition as predicted by solvent exposure, stratified by education and adjusted for sociodemographic and behavioral factors.

RESULTS

Solvent exposure rates were higher among less-educated patients. Within this group, there was a dose-response relationship between lifetime exposure to each solvent type and RR for poor cognition (e.g., for high exposure to benzene, RR = 1.24, 95% confidence interval 1.09-1.41), with significant linear trends (p < 0.05) in 3 out of 4 solvent types. Recency of solvent exposure also predicted worse cognition among less-educated patients. Among those with secondary education or higher, there was no significant or near-significant relationship between any quantification of solvent exposure and cognition.

CONCLUSIONS

Solvent exposure is associated with poor cognition only among less-educated individuals. Higher cognitive reserve in the more-educated group may explain this finding.

Job strain in relation to body mass index: pooled analysis of 160 000 adults from 13 cohort studies

BACKGROUND

Evidence of an association between job strain and obesity is inconsistent, mostly limited to small-scale studies, and does not distinguish between categories of underweight or obesity subclasses.

OBJECTIVES

To examine the association between job strain and body mass index (BMI) in a large adult population.

METHODS

We performed a pooled cross-sectional analysis based on individual-level data from 13 European studies resulting in a total of 161 746 participants (49% men, mean age, 43.7 years). Longitudinal analysis with a median follow-up of 4 years was possible for four cohort studies (n = 42 222).

RESULTS

A total of 86 429 participants were of normal weight (BMI 18.5-24.9 kg m(-2) ), 2149 were underweight (BMI < 18.5 kg m(-2) ), 56 572 overweight (BMI 25.0-29.9 kg m(-2) ) and 13 523 class I (BMI 30-34.9 kg m(-2) ) and 3073 classes II/III (BMI ≥ 35 kg m(-2) ) obese. In addition, 27 010 (17%) participants reported job strain. In cross-sectional analyses, we found increased odds of job strain amongst underweight [odds ratio 1.12, 95% confidence interval (CI) 1.00-1.25], obese class I (odds ratio 1.07, 95% CI 1.02-1.12) and obese classes II/III participants (odds ratio 1.14, 95% CI 1.01-1.28) as compared with participants of normal weight. In longitudinal analysis, both weight gain and weight loss were related to the onset of job strain during follow-up.

CONCLUSIONS

In an analysis of European data, we found both weight gain and weight loss to be associated with the onset of job strain, consistent with a 'U'-shaped cross-sectional association between job strain and BMI. These associations were relatively modest; therefore, it is unlikely that intervention to reduce job strain would be effective in combating obesity at a population level.

Influence of maternal and paternal IQ on offspring health and health behaviours: evidence for some trans-generational associations using the 1958 British birth cohort study

PURPOSE

Individuals scoring poorly on tests of intelligence (IQ) have been reported as having increased risk of morbidity, premature mortality, and risk factors such as obesity, high blood pressure, poor diet, alcohol and cigarette consumption. Very little is known about the impact of parental IQ on the health and health behaviours of their offspring.

METHODS

We explored associations of maternal and paternal IQ scores with offspring television viewing, injuries, hospitalisations, long standing illness, height and BMI at ages 4 to 18 using data from the National Child Development Study (1958 birth cohort).

RESULTS

Data were available for 1446 mother-offspring and 822 father-offspring pairs. After adjusting for potential confounding/mediating factors, the children of higher IQ parents were less likely to watch TV (odds ratio (95% confidence interval) for watching 3+ vs. less than 3hours per week associated with a standard deviation increase in maternal or paternal IQ: 0.75 (0.64, 0.88) or 0.78 (0.64, 0.95) respectively) and less likely to have one or more injuries requiring hospitalisation (0.77 (0.66, 0.90) or 0.72 (0.56, 0.91) respectively for maternal or paternal IQ).

CONCLUSIONS

Children whose parents have low IQ scores may have poorer selected health and health behaviours. Health education might usefully be targeted at these families.

Diagnosis-specific sick leave as a long-term predictor of disability pension: a 13-year follow-up of the GAZEL cohort study

BACKGROUND

Factors that increase the risk of labour market exclusion are poorly understood. In this study, we examined the extent to which all-cause and diagnosis-specific sick leave predict subsequent disability pension (DP).

METHODS

Prospective cohort study of 20 434 persons employed by the French national gas and electric company (the GAZEL study). New sick-leave spells >7 days in 1990-1992 were obtained from company records. Follow-up for DP was from 1994 to 2007.

RESULTS

The HR, adjusted for age and occupational position, for DP was 3.5 (95% CI 2.7 to 4.5) in men and 2.6 (95% CI 1.9 to 3.5) in women with one or more sick-leave spells >7 days compared with those with no sick leave. The strongest predictor of DP was sick leave with a psychiatric diagnosis, HR 7.6 (95% CI 5.2 to 10.9) for men and 4.1 (95% CI 2.9 to 5.9) for women. Corresponding HRs for sick leave due to circulatory diagnoses in men and women were 5.6 (95% CI 3.7 to 8.6) and 3.1 (95% CI 1.8 to 5.3), for respiratory diagnoses 3.9 (95% CI 2.6 to 5.8) and 2.6 (95% CI 1.7 to 4.0), and musculoskeletal diagnoses 4.6 (95% CI 3.4 to 6.4) and 3.3 (95% CI 2.2 to 4.8), respectively.

CONCLUSIONS

Sick leave with a psychiatric diagnosis is a major risk factor for subsequent DP, especially among men. Sick leave due to musculoskeletal or circulatory disorders was also a strong predictor of DP. Diagnosis-specific sick leave should be recognised as an early risk marker for future exclusion from the labour market.

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 the onset of depressive and anxiety symptoms in middle-aged employees. Participants were 2960 full-time employees aged 44 to 66 years (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 a prospective analysis of participants with no depressive (n=2549) or anxiety symptoms (n=2618) at baseline, Cox proportional hazard analysis adjusted for baseline covariates showed a 1.66-fold [95% confidence interval (CI) 1.06-2.61] risk of depressive symptoms and a 1.74-fold (95% CI 1.15-2.61) risk of anxiety symptoms among employees working more than 55 h/week compared with employees working 35-40 h/week. Sex-stratified analysis showed an excess risk of depression and anxiety associated with long working hours among women [hazard ratios (HRs) 2.67 (95% CI 1.07-6.68) and 2.84 (95% CI 1.27-6.34) respectively] 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 the development of depressive and anxiety symptoms in women.

Changes in C-reactive protein levels before type 2 diabetes and cardiovascular death: the Whitehall II study

OBJECTIVE

Prospective studies show that high C-reactive protein (CRP) levels predict diabetes and cardiovascular disease (CVD), but changes in this marker preceding disease onset are not well characterized. This study describes CRP trajectories prior to type 2 diabetes onset and fatal CVD.

METHODS

In a prospective cohort of 7350 British civil servants (70% male, mean age 51 years), 558 incident type 2 diabetes cases (75-g oral glucose tolerance test, doctor's diagnosis, or self-report) and 125 certified fatal cardiovascular events were observed during a median follow-up of >14 years. Trajectories of logarithmically transformed CRP levels prior to incident diabetes or fatal cardiovascular event (cases), or the end of follow-up (controls) were calculated using multilevel modeling.

RESULTS

Baseline CRP levels were higher among participants who developed diabetes (median (interquartile range) 1.44 (2.39) vs 0.78 (1.21) mg/l) or fatal CVD (1.49 (2.47) vs 0.84 (1.30) mg/l) compared with controls (both P<0.0001). In models adjusted for age, sex, body mass index, ethnicity, and employment grade, CRP levels increased with time among both incident diabetes cases and controls (P<0.0001), but this increase was less steep for cases group (P<0.05). CRP levels followed increasing linear trajectories in fatal cardiovascular cases and controls (P<0.0001) with no slope difference between the groups.

CONCLUSIONS

CRP levels were higher among those who subsequently developed diabetes or died from CVD. For type 2 diabetes, age-related increase in CRP levels was less steep in the cases group than in controls, whereas for fatal CVD these trajectories were parallel.

The association of cognitive performance with mental health and physical functioning strengthens with age: the Whitehall II cohort study

BACKGROUND

Cognitive performance has been associated with mental and physical health, but it is unknown whether the strength of these associations changes with ageing and with age-related social transitions, such as retirement. We examined whether cognitive performance predicted mental and physical health from midlife to early old age.

METHOD

Participants were 5414 men and 2278 women from the Whitehall II cohort study followed for 15 years between 1991 and 2006. The age range included over the follow-up was from 40 to 75 years. Mental health and physical functioning were measured six times using SF-36 subscales. Cognitive performance was assessed three times using five cognitive tests assessing verbal and numerical reasoning, verbal memory, and phonemic and semantic fluency. Socio-economic status (SES) and retirement were included as covariates.

RESULTS

High cognitive performance was associated with better mental health and physical functioning. Mental health differences associated with cognitive performance widened with age from 39 to 76 years of age, whereas physical functioning differences widened only between 39 and 60 years and not after 60 years of age. SES explained part of the widening differences in mental health and physical functioning before age 60. Cognitive performance was more strongly associated with mental health in retired than non-retired participants, which contributed to the widening differences after 60 years of age.

CONCLUSIONS

The strength of cognitive performance in predicting mental and physical health may increase from midlife to early old age, and these changes may be related to SES and age-related transitions, such as retirement.

Work disability following major organisational change: the Whitehall II study

BACKGROUND

Privatisation and private sector practices have been increasingly applied to the public sector in many industrialised countries. Over the same period, long-term work disability has risen substantially. We examined whether a major organisational change--the transfer of public sector work to executive agencies run on private sector lines--was associated with an increased risk of work disability.

METHODS

The study uses self-reported data from the prospective Whitehall II cohort study. Associations between transfer to an executive agency assessed at baseline (1991-1994) and work disability ascertained over a period of approximately 8 years at three follow-up surveys (1995-1996, 1997-1999 and 2001) were examined using Cox proportional hazard models.

RESULTS

In age- and sex-adjusted models, risk of work disability was higher among the 1263 employees who were transferred to an executive agency (HR 1.90, 95% CI 1.46 to 2.48) compared with the 3419 employees whose job was not transferred. These findings were robust to additional adjustment for physical and mental health and health behaviours at baseline.

CONCLUSIONS

Increased work disability was observed among employees exposed to the transfer of public sector work to executive agencies run on private sector lines. This may highlight an unintentional cost for employees, employers and society.

Physical and cognitive function in midlife: reciprocal effects? A 5-year follow-up of the Whitehall II study

BACKGROUND

Cognitive and physical functions are closely linked in old age, but less is known about this association in midlife. Whether cognitive function predicts physical function and whether physical function predicts cognitive function were assessed in middle-aged men and women.

METHODS

Data were from Whitehall II, an ongoing large-scale, prospective occupational cohort study of employees from 20 London-based white-collar Civil Service departments. The participants, 3446 men and 1274 women aged 45-68 years at baseline (1995-1997), had complete data on cognitive performance and physical function at both baseline and follow-up (2002-2004). A composite cognitive score was compiled from the following tests: verbal memory, inductive reasoning (Alice Heim 4-I), verbal meaning (Mill Hill), phonemic and semantic fluency. Physical function was measured using the physical composite score of the short form (SF-36) scale. Average follow-up was 5.4 years.

RESULTS

Poor baseline cognitive performance predicted poor physical function at follow-up (beta = 0.08, p<0.001), while baseline physical function did not predict cognitive performance (beta = 0.01, p = 0.67). After full adjustment for sociodemographic, behavioural and biological risk factors, baseline cognitive performance (beta = 0.04 p = 0.009) remained predictive of physical function.

CONCLUSION

Despite previous work indicating that the association between physical and cognitive performance may be bidirectional, these findings suggest that, in middle age, the direction of the association is predominantly from poor cognition to poor physical function.

Hostility and depressive mood: results from the Whitehall II prospective cohort study

BACKGROUND

The psychosocial vulnerability model of hostility posits that hostile individuals, given their oppositional attitudes and behaviours, are more likely to have increased interpersonal conflicts, lower social support, more stressful life events (SL-E) and higher likelihood of depression. However, little research has tested this hypothesis using large-scale prospective samples. The present study aims to assess the predictive value of hostility for depressive mood.

METHOD

Data are from 3399 participants in the Whitehall II cohort study, aged 35-55 years at baseline (phase 1 1985-1988). Cynical hostility was measured at phase 1. Depressive mood was assessed at phase 7 (2002-2004). Sociodemographic characteristics, health-related behaviours, common mental disorders and antidepressant medication intake were assessed at phase 1. SL-E and confiding/emotional support were measured at phases 1, 2 (1989-1990) and 5 (1997-1999).

RESULTS

Compared with participants in the lowest quartile of cynical hostility, those in the highest quartiles were more likely to have depressive mood [second quartile: odds ratio (OR) 1.58, 95% confidence interval (CI) 1.14-2.20; third quartile: OR 2.78, 95% CI 2.03-3.77; fourth quartile: OR 4.66, 95% CI 3.41-6.36] in analysis adjusted for sociodemographic characteristics. This graded association was somewhat attenuated (18%) but remained robust to adjustments for the covariates measured at baseline and follow-up. The association was also evident in participants free of mental health difficulties at baseline.

CONCLUSIONS

Cynical hostility is a strong and robust predictor of depressive mood. Consideration of personality characteristics may be crucial to the understanding and management of depression.

Prevalence of educational inequalities in obesity between 1970 and 2003 in France

This paper examines trends in obesity rates and education-related absolute and relative inequalities in obesity over the last 40 years in France. Data are drawn from the French Decennial Health Surveys of 1970, 1980, 1991 and 2003. The difference in obesity rates between the least- and most-educated, the Slope Index of Inequality, is used to estimate absolute inequalities in obesity. The ratio of the corresponding rates, the Relative Index of Inequality, reveals the relative inequalities in obesity. Obesity rates were similar in men and women, but educational inequalities were greater in women. Obesity rates were similar over the first three surveys but increased for all in the 2003 survey. This increase was accompanied by increases in absolute inequalities in men (P = 0.04) from a Slope Index of Inequality of 4.80% (95% confidence interval [CI] = 2.27, 7.32) to 8.64% (95% CI = 5.97, 11.32) and women (P = 0.004) from 8.90% (95% CI = 6.18, 11.63) to 14.57% (95% CI = 11.83, 17.32). Relative inequalities in obesity remained stable over the 40 years. Recent increase in obesity rates in France is accompanied by increases in absolute education-related inequalities, while relative inequalities have remained stable; this suggests that obesity rates have increased at a much faster rate in the low-education groups.

Socioeconomic position and cognitive decline using data from two waves: what is the role of the wave 1 cognitive measure?

BACKGROUND

Analysis of change in health status using data from two waves can be examined either adjusted or unadjusted for baseline health status. The effect of socioeconomic position (SEP) on cognitive change was assessed using both these strategies and the implications of the analyses are discussed.

METHODS

Data from 1261 men and 483 women of the Whitehall II cohort study, aged 50-55 years at wave 1, were used. Cognition was assessed at both waves using a test of verbal memory, and two tests of verbal fluency. Analysis of variance (ANOVA) was used to estimate the effect of SEP on change score and analysis of covariance (ANCOVA) was used to estimate this effect adjusted for the baseline cognitive score. The ANCOVA estimates were corrected for bias due to measurement error (estimated based on 3-month test-retest). Finally, ANCOVA estimates were examined for increasing levels of measurement error.

RESULTS

The results of the ANOVA suggest no effect of SEP on cognitive decline. In contrast, the ANCOVA suggests significantly greater cognitive decline in the lower SEP groups. However, the ANCOVA estimates for the effect of wave 1 cognition show evidence for regression to the mean due to the presence of measurement error. The corrected ANCOVA estimates show no association between SEP and cognitive decline.

CONCLUSIONS

Results from analysis of change using two waves of observational data, when adjusted for baseline, should be interpreted with caution.

Cardiorespiratory risk factors as predictors of 40-year mortality in women and men

OBJECTIVE

Most historical studies of cardiorespiratory risk factors as predictors of mortality have been based on men. This study examines whether they predict mortality over long periods in women and men.

DESIGN

Prospective cohort study.

SETTING

Participants were employees of the General Post Office.

METHODS

Risk factor data were collected via clinical examination and questionnaire, 1966-7. Associations between cardiorespiratory risk factors and 40-year mortality were determined for 644 women and 1272 men aged 35-70 at examination.

MAIN OUTCOME MEASURES

All-cause, cardiovascular (CVD), cancer and respiratory mortality.

RESULTS

Associations between systolic blood pressure and all-cause and stroke mortality were equally strong for women and men, hazard ratio (95% confidence interval) 1.25 (1.1 to 1.4) and 1.18 (1.1 to 1.3); and 2.17 (1.7 to 2.8) and 1.69 (1.4 to 2.1), respectively. Cholesterol was higher in women and was associated with all-cause 1.22 (1.1 to 1.4) and CVD 1.39 (1.2 to 1.7) mortality, while associations between 2-hour glucose and all-cause 1.15 (1.1 to 1.2), coronary heart disease (CHD) 1.25 (1.1 to 1.4) and respiratory mortality 1.21 (1.0 to 1.5) were observed in men. Obesity was associated with stroke in women (2.42 (1.12 to 5.24)) and CHD in men (1.59 (1.02 to 2.49)), while ECG ischaemia was associated with CVD in both sexes. The strongest, most consistent predictor of mortality was smoking in women and poor lung function in men. However, evidence of sex differences in associations between the cardiorespiratory risk factors measured and mortality was sparse.

CONCLUSIONS

Data from a 40-year follow-up period show remarkably persistent associations between risk factors and cardiorespiratory and all-cause mortality in women and men.

Hostility and trajectories of body mass index over 19 years: the Whitehall II Study

The authors examined the associations of hostility measured in adulthood with subsequent body mass index (BMI; weight (kg)/height (m)(2)) assessed at 4 time points over a 19-year period (1985-2004) in a United Kingdom cohort study. A total of 6,484 participants (4,494 men and 1,990 women) aged 35-55 years at baseline (1985-1988) completed the Cook-Medley Hostility Scale. BMI was assessed upon medical examination in phases 1 (1985-1988), 3 (1991-1993), 5 (1997-1999), and 7 (2002-2004). Mixed-models analyses of repeated measures showed clear evidence of increasing BMI over follow-up in both sexes. In women, higher levels of hostility were associated with higher BMI at baseline, and this effect remained constant throughout the follow-up period. In men, hostility levels were also strongly associated with BMI at baseline, but results for the interaction between time and hostility also suggested that this association increased over time, with persons in the highest quartile of hostility gaining an excess of 0.016 units (P = 0.023) annually over the follow-up period as compared with persons in the lowest quartile. The authors conclude that the difference in BMI as a function of hostility levels in men is not stable over time.

Sickness absence as a prognostic marker for common chronic conditions: analysis of mortality in the GAZEL study

OBJECTIVES

To determine whether sickness absence is a prognostic marker in terms of mortality among people with common chronic conditions.

METHODS

Prospective occupational cohort study of 13,077 men and 4871 women aged 37-51 from the National Gas and Electricity Company, France. Records of physician-certified sickness absences over a 3-year period were obtained from employers' registers. Chronic conditions were assessed in annual surveys over the same period. The main outcome measure was all-cause mortality (803 deaths, mean follow-up after assessment of sickness absence: 13.9 years).

RESULTS

In Cox proportional hazard models adjusted for age, sex, socioeconomic position and co-morbidity, >28 annual sickness-absence days versus no absence days was associated with an excess mortality risk among those with cancer (hazard ratio 5.4, 95% CI 2.2 to 13.1), depression (1.7, 1.1 to 2.8), chronic bronchitis or asthma (2.7, 1.6 to 4.6) and hypertension (1.6, 1.0 to 2.6). The corresponding hazard ratios for more than five long (>14 days) sickness-absence episodes per 10 person-years versus no such episodes were 5.4 (2.2 to 13.1), 1.8 (1.3 to 2.7), 2.0 (1.3 to 3.2) and 1.8 (1.2 to 2.7), respectively. Areas under receiver operating characteristics curves for these absence measures varied between 0.56 and 0.73, indicating the potential of these measures to distinguish groups at high risk of mortality. The findings were consistent across sex, age and socioeconomic groups and in those with and without co-morbid conditions.

CONCLUSION

Data on sickness absence may provide useful prognostic information for common chronic conditions at the population level.

Diagnosis-specific sickness absence and all-cause mortality in the GAZEL study

BACKGROUND

This study aims to examine diagnosis-specific sickness absence as a risk marker for all-cause mortality.

METHODS

Prospective occupational cohort (the GAZEL study). Medically certified sickness absence spells >7 days for 15 diagnostic categories, 1990-1992, were examined in relation to all-cause mortality, January 1993-February 2007. The reference group for each diagnostic category was participants with no spell >7 days for that diagnosis. The participants were French public utility workers (5271 women and 13 964 men) aged 37-51 years in 1990, forming the GAZEL study. Over the follow-up period, there were 144 deaths in women and 758 in men.

RESULTS

7875 employees (41.0%) had at least one spell of sickness absence >7 days over the 3-year period. The commonest diagnoses were mental disorders, musculoskeletal diseases, respiratory diseases and external causes in both sexes; genitourinary diseases in women, and digestive and circulatory diseases in men. Of these common diagnoses, mental disorders in women, hazard ratio (95% confidence intervals) 1.24 (1.1 to 1.4), and mental disorders 1.35 (1.3 to 1.5), digestive diseases 1.29 (1.1 to 1.6) and circulatory diseases 1.35 (1.2 to 1.6) in men were associated with mortality after adjustment for age, employment grade and sickness absence in all other diagnostic categories.

CONCLUSIONS

Employees with medically certified absence spells of 1 week or more over a 3-year period had a 60% excess risk of early death. In women and men this excess risk was associated with some of the commonest diagnoses of sickness absence, in particular mental disorders. Sickness absence for mental disorders may be a useful early indicator of groups at increased risk of fatal disease.